Oil cooling

This is not exactly a 'new' thread, since there has been countless posts relating to this subject, and I have read them all --- twice. What I need is opinions from those in the know on one of problems relating to oil temps. My situation is not critical, but uncomfortable for me. I have an RV-8 with an ECI Titan O-360, carbed, one electronic ignition, and 9:1 pistons. My cruise oil temp up high with OAT's in the 55-60 degree range are running 200-207. Temps increase in the traffic pattern or during formation flying, with temps reaching 210-217. My baffles are tight - they would hold water if turned upside-down. I've RTV'd every possible opening around my oil cooler (Van's FWF Niagra 2002A). Today I removed my vernatherm and found out that it only touches the seat on about half of the circumference of the tapered valve surface. What I need to know is, does this make that much difference? Even though it doesn't seat all the way around, there can't be that much of a gap in the area not making contact with the seat. How much will that effect oil temperature? I know this oil passing past the seat is not going through the cooler, but how much oil is getting bypassed? And how bad is that? There is a procedure where you can lap the seat up to .010, but then the temp where the vernatherm makes contact and starts cooling through the oil cooler is higher. The alternative is to get another seat - ie. oil filter adapter - and hope this one is seated correctly. I installed and flight tested another new vernatherm today and there was no change.

Another thing I tried after talking to a friend who got this idea from ECI. He said any Van's airplane could get a 20 degree improvement in oil cooling by putting a blocking plate over the #4 cylinder cooling fins where they almost touch the oil cooler on the Van's baffle. Theoretically, the #4 cylinder exhaust valve which is about an inch from the bottom of the oil cooler and experiences temperature approaching 1400 degrees, has a negative effect on oil temps because air passes over this area of the fins and some of it is sucked through the oil cooler. Even though putting a plate in front of this area of the cooler, thereby deflecting the cowl air down through the fins with none going through the oil cooler - effectively blocks about 1/3 of the oil cooler, this is still better than having very hot air going through the oil cooler. Well, I made this modification, and I curved the top of it to 'catch' some air and send it down through the fins to cool the exhaust area of the fins. Net result: zero.... it made absolutely no difference, good or bad. No noticeable difference in #4 CHT or in oil temperature.

My friend Jon Thocker with an almost identical airplane, but a SW8406 cooler is getting 10-15 degree cooler oil. He doesn't have the electronic ignition either. That gives me a higher CHT, because of more complete burning of the gasses in the combustion chamber due to earlier ignition timing, and lower EGT's, because there is less burning going on heading down the exhaust pipe. These numbers are verified in side by side testing with out two airplanes.

What I need is advice on what I can do to lower my oil temps. Obviously, I need to figure out the vernatherm issue first, even if the difference is small. Next, should I get another cooler? The SW8406 is possibly good for 10 degrees or maybe more. The 8432 will give me even more, but I have to remove and modify my rear baffle. I'd like to fix this problem without spending my wife's future windfall if possible. The 8406 is $615.00, and the 8432 is $661.00 at Pacific (both are more at Spruce). I've thought about trying a Mocal/Setrab, but haven't gotten the gumption yet. It would require some engineering and a lot of unknowns - but this is summer and I want to fly.

Suggestions??? I mostly want to know about this vernatherm issue....

THANKS,

According to the spec sheets for Lycoming 235 and 320, the oil cooler system without Vernatherm has a limiting prssure drop across the oil cooler of 35 psi and with the Vernatherm it's 75 psi, in which case the oil cooler is bypassed. The maximum temp spec for the oil is 245 F, and if you're using semi-synthetic oil, that's not a problem. The engine runs more efficiently with higher temps on the cylinders and oil. I choose to run my CHTs around 375F-395F, and my oil between 100C and 110C, 212F-230F. 210F-217F doesn't seem all that bad to me! It's a choice based on feelings.

Any chance you can borrow Jon's SW cooler for a test? That would help eliminate the cooler and possibly save you some serious $.
Are your CHTs running okay? Your OTs are high, but not excessive (at least from what I've heard) I'd be more concerned about CHT than OT.
How many hours on the engine and what kind of oil are you running?

We just fought this on a friends RV8. His temps were OK for a while and started creeping up to the 210-215 range. We did all the normal things like reasealing any suspicious baffle leaks, tried the small baffle at the #4 cylinder etc. We made a spacer that moved the oil cooler aft 3/4" in an attempt to provide a small plenumn at the oil cooler inlet side. When recowling the engine after the spacer mod, we found the seal at the snorkel had torn loose from the airbox. We suspect that this seal defect allowed ram air to pressurize the lower cowl area and disrupted the airflow from the high pressure upper cowl area to the supposedly lower pressure bottom cowl area. The temps are now lower by 10-15 degrees after the snorkle seal repair and the oil cooler spacer. We don't know for sure which change had the most affect but we are happy with the results.

I'm sure you've already checked this, but a lot of folks don't seal the ends of the inlet ramps on the upper cowling. The ramps server as nice tunnels to pump cooling air from the pressurized to the non-pressurized section of the cowling. the tighter your baffling is, the better these tubes work to defeat your cooling! Make sure the interior faces of the space between the inlet ramps and the upper cowl are glassed over. Doesn't have to be pretty...

FWIW-

Not the vernatherm- I replaced the Vernatherm, spring and cleaned up the seat to zero improvement in a citabria that was running a little warm as yours is. Cleaning up the baffle leaks and extending the outlet shroud improved that install. So for me I would not look at the Vernatherm at first. My issue for our RV was to replace the cracked Vans oil cooler- It was too low and too close to the #4 cyl anyway. Being so low on that Cyl is probably what caused the crack from excess Cyl heat. After replaceing with a little larger cooler and raising the mounting as high in the baffle as possible- that was the cure. -FWIW and Your MMV

Scott.

I feel the pain. I am in the same situation but my oil temps at
cruise are 225. Hard climb to 6500' and it gets to 235.
I put the 8406 on and it didn't change much. Did you
talk with ECi.
I have the James plenum and cowl.
I will check my snorkle attatch area which could be some
of my problem.
How many hours do you have on your engine?? could that
be some of it.

Everyone keeps telling me to fly as is at 225. Just be careful.

Give me a shout if you need to.
Boomer

Like an earlier post indicates...

...it's not the Vernatherm. On a previous plane, I replaced Vernatherm valves multiple times chasing the same (high) oil temp problem. Vernatherms are near useless. Like others have stated, I learned to live with the higher (but acceptable) temperatures. I would suggest focussing on some of the good ideas posted by others.

Good luck,

Dean Pichon

As you probably read on other recent posts, I have struggled with high oil temps, CHT's and EGT's on my ECI -0320. I have seen my temps drop from about 210 to where they are right now at about 195. Everyone say's check the baffles, check the baffles. I did and didn't see any leaks. Here's what I have done so far,

1.Installed doubler strips on the baffles higher to put more pressure on the baffling material.

2.Reduced my oil pressure to 73 psi in cruise.

3.Taped up the inlets with foil tape.

The tape looks really goofy. My wife was not thrilled. She thought the plane was being held together with duct tape. However, it's a sure fire way to block the air from going where you don't want it. I am going to work on the fiber glassing the inlets using the tape as a mold ASAP.

I am running P-mags and my CHT's, oil and EGT's got hotter when I hooked up the manifold pressure line during the climb. EGT's seems to be lower at cruise peak as CHTS are about the same.

Right now I am seeing about 390 CHT in cruise, 1400 EGT and 195-198 oil temp

Guy Prevost said:

I'm sure you've already checked this, but a lot of folks don't seal the ends of the inlet ramps on the upper cowling. The ramps server as nice tunnels to pump cooling air from the pressurized to the non-pressurized section of the cowling. the tighter your baffling is, the better these tubes work to defeat your cooling! Make sure the interior faces of the space between the inlet ramps and the upper cowl are glassed over. Doesn't have to be pretty...

Click to expand...

This is only necessary if you do not trim your baffle edges to parallel the ramps so that the baffle seal material seals against the ramps on the inboard and outboard sides of the inlet (that is the way it is intended to be). If this is done, there is no flow path through the opening below the ramp.

Geez, beat me up, I give.

Thanks for all the responses guys. Mike - great idea, in fact Jon Thocker also thought of it and he let me borrow his SW8406 cooler today. Result: in as identical conditions as you can get between yesterday and today, my cruise oil temp ran a good 15 degrees cooler with the SW vs. the Niagra 2002A. The OAT both days were the same (90+ degrees), but it was a little more humid today - thick sticky air - rain is on the way... Anyway, yesterday I saw cruise oil temperature of 205. Today with Jon in the back (heavier) I saw 188. Yesterday, by the time I got into the traffic pattern and landed it was up to 213, today it got to about 198-200 at that point. These temps are a little higher than what Jon is seeing, so I think the vernatherm leaking has something to do with that. Lycoming lists this problem as one to look for when experiencing high oil temps, and mine is only making contact on about 50% of the circumference of the valve. I tried a new Lycoming vernatherm valve and it made no difference, so that tells me the seat is not sealing flush on the valve. I will probably send my oil filter adapter to Jimmy at JB Aircraft engines to have him re-face the seat. The kit to do this myself is more expensive than a new oil filter adapter, which is a little over $300.00 from ECI. My engine is still pretty new with only a little less than 200 hours on it, so I'm hoping ECI will stand by their product, since it never has been right, and just give me a new one.... guess I'll find out tomorrow. I think the vernatherm problem might be worth another 5 - 8 degrees, in addition to the 15 I'll get from a new cooler coming from Pacific Oil Cooler. Anybody want to buy a used Niagra - only 175 hours on it....
As another data point, our friend Larry has an RV-8 that Jon built and it has a Positech cooler on it. He flew home today from NY and had a cruise oil temp of about 193. The Positech looks similar to the SW. Larry's airplane doesn't have 9:1 pistons like Jon and mine, so that may mean his cooler wouldn't perform quite as well as the SW on our airplanes, but it's better than the Niagra. Jon's airplane and mine are nearly identical. We get about the same CHT's (350-360), EGT's, and same true airspeed at the same power setting. He is getting 20 degree cooler oil with his oil cooler. I don't think the vernatherm working correctly is going to make that much difference, but the oil cooler obviously does. I'm still going to do something about that vernatherm leakage and I'll let you know how much it's worth.

Temp calibration?

Hi Scott.

This is probably a longshot, but how do you measure your oiltemp?
If it's electronically via an EFIS, maybe the oil temp calibration is off?

I can only speak for AFS, but on that one you can adjust your oil-temp readings with a calibration factor (if I remember correctly now) to show the correct oiltemp.

The AFS comes pre-set with the correct calibration factors from the company, but maybe they've changed somehow? For example during a software update if you've done some of those?
I know these changes schouldn't happen, but it's only a computer using software to show something, and we all know what can happen to software and computers...

If you have another type of EFIS, maybe they have the same calibration possibilities?

If the above is the case, maybe you could somehow "T-in" an analog temp gauge?

I like to add that I have a AFS EFIS 3500 myself and LOVE it, so this is NOT a bashing of AFS products! It's the best instrument I've ever seen and I've ordered another one for my second RV. Their customer care and support are the best too!
No, this is merely a a suggestion to check the software, just in case...

Thanks Alf,
I'm pretty sure my Dynon doesn't have a programmable adjustment for my oil temp, but I'll check. The temp probe came with the FLTDek 180, so it's probably set up for the right one. I am going to be removing my oil filter adapter today to have the vernatherm seat repaired or maybe just replace the whole adapter. While it's off, I'll have the oil temp probe checked to make sure it's accurate. Incidentally, if anyone is thinking about buy the kit to reface your vernatherm seat, Lycoming gets $2465.67 for it. It's a fancy reamer. You can probably find one cheaper somewhere, or you may be able to borrow one, but sending the unit to a good engine shop would probably be you best bet. Buying a new adapter one is far cheaper than buying the tool to fix it - part# AEL22772-1 from ECI is $314.89. The ECI part like mine is the 90 degree oil filter adapter and I have a spacer between it and the accessory case.

Scott, dynon has 2 different temp senders. With skyview you have select which one you have installed. Either 1/8 or 5/8 npt. If you have wrong one selected you will get bogus readings.

I just got off the phone with my engine builder, Jimmy Brod, in Sebring, FL, and learned something new about my vernatherm seat. I have an ECI Titan engine with the ECI 90 degree oil filter adapter and spacer. With this setup, the vernatherm does not seat inside the oil filter adapter like it does on the Lycoming version where the oil filter points straight aft and the vernatherm is installed from the bottom up. In that adapter, the seat is inside the adapter. On the ECI 90 degree like mine, the seat is the hole in the spacer. The problem with this is, there is some play between the two parts because of the long bolts that go all the way through the oil filter adapter, spacer, and then into the case. The bolt holes aren't tight around the bolt so it allows a small amount of play between these two parts, and therefor the seat in the spacer may not be aligned perfectly with the vernatherm valve. Finding the center during assembly with the vernatherm in it's cold retracted position is sort of a voodoo science, I think. I could heat up the whole assembly and then try to install it hot before it cools so that the vernatherm is extended and feel for the 'sweet spot', but that doesn't sound easy. I'm going to remove the parts today and play with it and check to make sure the seat in the spacer isn't damaged, but I think it's kind of a lucky thing to get it mounted in the perfect spot.
The 90 degree adapter idea is great for making clean oil changes, but the standard Lycoming setup is far more accurate in terms of vernatherm operation.

Scott, this is the ECI adapter you have? (Sam Evans posted the photo in another thread some months back. Ignore the little red arrow.):



Interesting problem. Seems like you need a lineup pilot of some kind to screw into the vernatherm hole while bolting on the adapter.

No Way

There is no way to line up the Verni inside.
It is all set and the only thing it can do is move OUT and
hit the accessory case. Thats it.

Actually, there is a way, but it takes a lot of skill and a little luck. Here's what you do: remove the oil filter adapter and spacer with the vernatherm remaining in place. Clean the parts and install new gaskets, this time with a little permatex on the gasket that goes between the adapter and spacer (ECI pn AEL22778). Bolt the adapter and spacer assembly together loosely with your long bolts and washers as needed. OK... then you heat to whole contraption up in an oil bath to about 200 degrees (I'm not sure how). It will maintain this temp for a while. While it's hot and the vernatherm is extended, align the two parts together, feeling for the nose of the vernatherm to nest into it's hole in the spacer. Hold this position while you tighten the bolts to hold it in place. Then you let it sit for a day or two to 'harden'. The two pieces are sort of 'glued' together with permatex now. Carefully remove the bolts and nuts and install the assembly on the engine in this configuration without disturbing the two pieces that are lightly glued together, thusly maintaining the proper alignment. I should have been a surgeon..... I think I like the pilot hole idea better. I'm looking for a reamer or something that will fill the bolt holes fairly tightly and not allow any movement during assembly on the engine. Other than that, I'll just put it all back together when I get my gaskets and hope I got lucky and they line up this time. The angled oil filter adapter is a handy system for making oil changes without as much mess, but it's a poorly designed system when you are using a spacer for engine mount clearance and you expect your vernatherm to function properly, which is much more critical.

A better idea as Dan mentioned, if I could get an old vernatherm and 'modify' it by removing the spring so it would stay extended and use that as a temporary pilot.... that could work if it's still straight... I think the difference between perfect and a little off is not much. When you think about it, it probaly doesn't take much to affect your indicated oil temperature. This uncooled engine oil is mixing with cooled oil and contaminating it. The pressure of the oil leaking past the vernatherm is higher than the oil that is coming out of the cooler and mixing with it because of oil cooler pressure drop, so a little leakage would have a more dramatic affect on oil temperature. The location of this leakage is very close to the oil temperature probe, so it's obvious. I need a manual valve in that location. With this setup, the vernatherm is a hindrance, not a help. I'm getting more P-O'd as I write this. It's hard to believe that a thinking person designed such a flimsy system. On the Beech 18 we had two different ways to manually control oil temperature. I wish I had one now...
My new SW8406 arrives next week and that will correct 90% of the high oil temp problem vs. the cheap Van's cooler, but I still don't like having something that doesn't work right...

Bruce,
After re-reading your post, I realized that you don't need the spacer for your RV-7, so there is not problem with alignment. Your verni should line up fine, and I'm sure it does. The RV-8 requires a spacer between the adapter and the accessory case for engine mount clearance. This setup with a spacer allows some play to exist between these two parts and the vernatherm interacts with both pieces - therein lies the problem. I think a lot of the variation with oil temperature in the RV-8 airplanes has something to do with this specific thing. It has more to do the the variable use of inferior oil coolers, though, but the vernatherm performance in the angled oil filter adapter/spacer setup is definately a negative factor. If I had it to do over, I would install the standard Lycoming oil filter adapter and deal with the mess during an oil change. The vernatherm in this installation is integral with the adapter, so alignment is not an issue.

Scott,
Consider doing a bench lineup with a hot vernatherm and pinning the adapter and spacer relationship. Drill and ream from the engine side of the spacer for two small roll pins.

You can lose the vernatherm altogether, and install the oil cooler bypass plunger and spring in the accessory case. Then using a ball valve on the oil cooler line you can control your oil temps from the cockpit. Larry Vetterman came up with this idea and said he lowered his oil temps 20 degrees, and it works out much better in the winter time also.

Bob, that's one I've never thought of. I need to look at my Emeraude engine again. Do you know if that will work on the 290D2 with the Tri-pacer (pie chaser) type cooler adapter?

Bob,
I've read your previous post about this method of eliminating the vernatherm and that sounds good to me, but I'm unclear how it could work. With the vernatherm gone, the bypass opening is wide open thereby pypassing the cooler all the time. The ball check valve in the accessory housing is for bypassing the cooler in case it becomes clogged I assume, but what closes up the hole where an expanded (hot) vernatherm would be? I suppose I could tap the hole in the spacer body where the vernatherm nests and install a pipe plug, but you don't say that in your post. Does Larry Vetterman have a description of this on any of his public sites as far as you know? Ironically I have removed the cap where the accessory check valve goes since it's more accessible right now and it's been slowly leaking. When the engine was built, someone must have tightened it down too tight on the crush washer.... so this would be a good time to go that route. If you have an idea how this works, please let me know.

Thanks,

One detail I forgot to mention. You take the vernatherm apart by removing a clip so all that's left of it is the cap, and you reinstall the cap. You have the part about the oil cooler bypass incorrect, its simply a plunger and spring that opens when the cooler is blocked (valve is closed.) You can call Larry and ask him about it...he was really pleased with the setup when I spoke to him last. I think having complete manual control over oil temps is a great thing...no need for blocking off the cooler in the winter time. He has the plunger/spring part #'s memorized and the ball valve is a $7.00 oil/gas valve available at Tractor Supply.

Scott,

If I were you, the first thing I would do is verify that the oil temp indications were correct. Put the oil temp sender in a pot of boiling water and see what the oil temp indication is. Keep in mind that the boiling point of water does decrease as the air pressure decreases (i.e. as the altitude increases). You can determine the boiling point for any pressure altitude at this site.

Right on, Kev! Always check the instrumentation first before doing any mods!

I have checked the indicator with the boiling water test, and it appers to be accurate compared to two other gages. I switched my Van's oil cooler with a borrowed SW8406 and my temperature dropped 17 degrees. A new SW oil cooler is on it's way to me from Pacific Oil Cooler. I wish I would have bought this one in the first place. I also plan on removing my vernatherm if I can purchase the spring and by-pass plunger that goes into the accessory case. The right angle adapter does not permit precise alignment of the vernatherm into it's seat because the bolt holes in the adapter are oversize and allow movement when mounting, and there's no way to tell if it's centered. Not having oil bypassing the cooler at this time of year sounds like a fine idea to me. I'll get the cockpit operated manual bypass installed before it gets cold. Should be easy to maintain correct oil temp when it's cold this winter with that system.
Thanks for all the input and advice. I'll report how it all works sometime this week hopefully.

Here's some pics of my oil temp sender test.



The beer can idea was too small, so I used a heater my wife had (second pic). It boiled water in about one minute. The probe is attached to the aluminum piece with an AN fitting (#8). The regular thermometer was use to check low temp rang and the digital meat thermomemeter at low temp - 100 to 120. When the water boiled the Dynon indicated 210 -211, and so did the meat thermometer.... good enough for me. Next is a pic of the hole above the oil filter adapter pad where the cap, spring, and bypass plunger will go as part of my vernatherm elimination as suggested by Rocketbob and Larry Vetterman. Next I think (can't see the photos in this post) is a picture of the uneven wear pattern on my vernatherm. You can see in the photo where is makes contact with the seat and where it doesn't. It moved a little when I re-installed it after testing another new vernatherm so there is some contact on about another third of the curcumference, but only about half of the circumference is actually making contact. The last pic (I just remembered) shows the relative size of the bolt holes in the spacer vs. the oil filter adapter. The adapter holes are about 30% bigger that the bolt diameter. The allows an unacceptable amount of play in the vernatherm seating area, which will cause uncooled oil bypassing the cooler. I can't imagine there are very many airplanes flying around with this system that have a perfect fit between vernatherm and vernatherm seat. Is it a big deal?? Probably not, but it definately deminishes the effectiveness of the oil cooler and in some cases, it may be more dramatic. Larry Vetterman says eliminating his vernatherm made a 20 degree difference in his oil temperature, according to RocketBob. I'll call Larry tomorrow - Monday - to get some more info, but it make sense to me.

rocketbob said:

You can lose the vernatherm altogether, and install the oil cooler bypass plunger and spring in the accessory case. Then using a ball valve on the oil cooler line you can control your oil temps from the cockpit. Larry Vetterman came up with this idea and said he lowered his oil temps 20 degrees, and it works out much better in the winter time also.

Click to expand...

I'm missing something here. I have the Lycoming oil filter adapter with the filter straight out the back and vernitherm mounted on the bottom facing up. I, too would like to eliminate the vernitherm but after the the bypass spring and plunger is reinstalled, doesn't something need to be installed to stop the oil from bypassing the cooler at the vernitherm seat, or can you just cap the vernitherm hole?

Hers's a pic that Dan H had posted that sort of shows the path of oil with the plunger in place - red dotted line:



With the bypass plunger and spring in place and the vernatherm valve removed, all oil is going through the cooler all the time (unless clogged), and none is passing through the vernatherm passage, because the plunger closes off this passage. This passage is labeld 'from pump' in the picture. No oil comes through this passage with the plunger installed unless there's a clog. You'll need to remove the vernatherm from it's cap (there's a retaining clip) and reinstall the cap. The washer can be reused if it's not damaged. The standard Lycoming oil filter adapter doesn't necessarily have the same fitting issues as the right angle adapter does, because in yours, the vernatherm seat is integral with the adapter. With the right angle adapter, the vernatherm seat is either the opening in the accessory case or the hole in the spacer and alignment of the vernatherm in this hole is the problem due to play in the adapter bolt holes. If your vernatherm is leaking, you could try a new vernatherm. I borrowed one from my local maintenance shop. If that doesn't help, you could have your seat faced with that $2500.00 tool, or better yet buy a new adapter (about $260.00 at Superior). Or you could just do away with it. The plunger and spring are $24.48 & $21.28 at Superior. I'm going with the latter because getting proper alignment is based solely on luck in my right angle/spacer installation. Oil temperature reduction will be based on the amount of oil leaking past the vernatherm when the oil is hot. Then you'll have to deal with trying to heat up the oil to around 180 in the winter with 100% of your oil going through the filter. The vernatherm begins to 'grow' at 150 degrees and starts sending oil through the cooler and reaches it's maximum 'growth' at 180-190 where all oil at this pint should be going through the cooler if it's not leaking. Minimum extension is .160" and max is about .250. I'm not sure if blocking air through the cooler will be enough to warm up your oil in the winter when 100% of the oil is circulating through the cooler, but I'm going to do this initially because I have the Van's oil cooler shutter and I'll just install it when it gets cold this fall to see if it works. I can always add the ball valve in the oil cooler line later and probably use the same control cable.

I realize I'm repeating myself here, but in hopes that if my thinking is wrong, someone here will let me know....

Scott,
I'd suggest a trial installation of the plunger and spring before mounting the oil filter adapter. You'll want to be sure the plunger seats fully below the level of the vernatherm bypass hole, and properly matches the bore diameter. Doesn't appear to have a tapered seat; if true then bore fit controls leakage, and leakage here will have the same effect as the poor vernatherm seat contact.

RE:ECi Oil Temp. Info

I have really enjoyed this tread. First great info/ideas. It is what VAF is about.

Now to my info/point/?

I have an ECi IOX Titan 360 with 9.0 to 1 compression ratio. I have a pressure plenum (Al top) for the baffle system. And the SW oil cooler. The engine now has a little over 80 hrs in it's first year of service. The only problems I seem to be having is a couple of oil weeps that I hope to track down during the condition inspections this week ..... and the one that really bugs me is the use of about a quart plus of oil per 10 hours.

My oil temps on a very hot day here in the 1xx degree southwest (Saint George Utah) runs between 200 to 209 with oil pressure about 55. This really bugged me until I had a conversation with Bobby Loper who ran my engine in for American Engine who built my engine and reading ECi's spec sheet.

The spec sheet confirms at T/O oil should be 180 and no more than 245 in cruise with CHT's at or below 425. Bobby said running at 200 to 210 ot and 400 to under 410 on CHT's is OK. This info blows my training that a happy engine is 180 oil temp / 380 CHT's. Plus at LOP my oil temps drop to 200 or below with CHT's in the 360 to 380 realm burning 7 GPH.....

Here is the site for the ECi info:

http://www.eci.aero/exp/eng_comparisons_brochure.pdf

I hope this isn't thread creep but may add some data to the ? what is the best temp to run our ECi type engines and if to high what to do about it?............

Frank @ 1L8 ...RV7A... Flying and Tracken (MT-RTG)

Yeah, you will find discrepancies in the specs between manufacturers, but our little engines are generally more robust than folks give them credit for - you dont fall out of the sky when your CHT goes above 400. Im not sure how many people are going to wait around for their oil temperature to get up to 180 degrees before take-off though, per ECI's recommendation. I go at 100.

erich

erich weaver said:

Yeah, you will find discrepancies in the specs between manufacturers, but our little engines are generally more robust than folks give them credit for - you dont fall out of the sky when your CHT goes above 400. Im not sure how many people are going to wait around for their oil temperature to get up to 180 degrees before take-off though, per ECI's recommendation. I go at 100.

erich

Click to expand...

I also go at 100. (There was a time when it was ok to launch when the needle came off the cold peg)

A minimum of 180 won't work for me. If I waited for it I'd never fly. It seldom goes over 170 in flight.

First thing... Dan, I looked down into my oil cooler bypass hole and it is definately tapered. I haven't received my plunger and spring yet, so I don't know how it all matches up, but if taper is the problem, at least there is some. Also, the plunger is like a cylinder, I think, with a tapered seat (at least that's what the picture looks like), and the vernatherm inlet passage should be blocked by the cylinder shoulders when seated. There are litterally thousands of hours in RV's with this non-vernatherm arrangement (including certified aircraft before the vernatherm's ill-fated arrival), and it works. I'll let you know what I find out.

Second.... I had a discussion with Larry Vetterman today and he (and his buddies) have extensive experience in dealing with vernatherms. They've been doing this for 25 years. Larry says that a good vernatherm will still bypass about 30% (!!) of the oil it sees, even when the oil is hot and it should be sending it all to the cooler... A good vernatherm to me is one that is in the Lycoming standard straight oil filter adapter, not the right angle version. In the Lycoming unit, at least the vernatherm seat is machined as a unit. When you are dealing with two parts that are separate, as in the right angle versions, it still requires accurate alignment, and one of the parts has built in 'slop'... excuse me, but who's the genius that designed this???

Frank, another thing Larry discussed with me was optimum oil temperature. These engines are 'loose' compared to modern automotive piston engines (still neanderthal in my opinion), and as such, expand with heat to become a 'tight' engine. That expansion occurs at an oil temperature of about 195 (this according to Larry's extensive experience/testing). At that temperature(+/- a couple) your tolerance should be at it's zenith as far as getting the most our of your engine. Cooler oil - 180 for example - or hot oil - 200+, is not optimum. Your compression ratio is not what it should be to get the most available energy out of your expensive fuel. Your CHT's are dependant on your air cooling efficiency (baffles) to a certain degree, but also upon the amount of fuel that's being consumed. Your oil cools things off in addition to providing lubrication, but if it's too cool or too hot, your rings don't fit as tight and you loose compression. You get blow-by and that robs power and contaminates your oil. The ability to control the temperature of your oil has an effect on power, fuel efficiency, and engine life. Depending on a system (vernatherm) that has a built in 30% definciency doesn't seem like a good idea to me. Of course, you become the 'hall monitor' when it comes to maintaining safe oil temperature limits.

When you take off on a cool morning with the oil cooler manual by-pass control closed and then become enthralled with the scenery or your bride in the other seat, and then miss the fact that your rising oil temperature (250... 300... counting) is cooking your oil and your engine,,,, don't blame Larry or me or anyone else here. You have to be a pilot with this system and be mindful of this, just like you would with manifold pressure, fuel quantity, or anything else. I'm not picking on anyone here, but please realize, if you decide to go with a manually controled oil temperature system, you are responsible for the outcome. The whole reason for the vernatherm in the first place is for pilots who are incapable of multi-tasking. Lycoming has attempted to engineer the dumb pilot out of the equation here. They've done this with a system that is not optimal, and in the case of this right angle adapter system, poorly engineered (Lycoming didn't design that, by the way). When you have an airplane that is tweaked, and a "TOTAL PERFORMANCE" airplane, I don't think you need this. For me, there is a better way. I'm looking forward to reporting the results, even though it's already been done countless times before - I have read it. The ability to control my oil temperature - without blocking the air - from the cockpit, precisely, is priceless (to me). Larry can control his oil temperature to within 1 degree with this manual system, regardless of the OAT.

You know what they say YMMV.... well, I think your mileage will vary. Stay tuned,,,, I'll let you know what my 'mileage' is.

RE:Experts

Scott and you other contributors....

Experts. I find it interesting how I can talked to ECi's best and brightest, then inquire of my local experts that have many years under the hood of these Lycoming type engines, then hear from my exhaust man (Vetterman has given much time in this area over the phone not to mention my 4 pipe exaust), and finally my main man Bobby Loper, who I mentioned has put many an ECi engine through all the torture test to gain certification position and to know how these engines do under all conditions over the life of an engine. Now the point: men I highly respect both mentioned above and here at VAF have varied positions on the sweet spot Temps these engines should ran at. What's a wet behined the ears airplane builder to do!!!!

Being an old used up High School Chemistry teacher I would say that for a given measuring device (Vernatherm) hooked up to a machine (our engine) there would be some plus or minus in the accuracy (error factor) of the system to measure the Temps. The question is is the machine and all it's auxillary parts optimize to minimize the error factor and does it give optimum results?

I must admit I built my plenum using the Robbie Attaway set up. RTV every conceivable hole, antied-up for a new SW oil cooler early in the life of the plane (first 10 hours), and so it goes......

Scott, I will look forward to your work on this situation. It will be great to see the results and how it imporves your temps and more importantly FLYING ENJOYMENT!!!!!!!

Frank @ 1L8 ...RV7A ... Flying kinda hot or just right!!!!!!! Man this sounds like the three bears??????

Scott Hersha said:

.

Second.... I had a discussion with Larry Vetterman today and he (and his buddies) have extensive experience in dealing with vernatherms. They've been doing this for 25 years. Larry says that a good vernatherm will still bypass about 30% (!!) of the oil it sees, even when the oil is hot and it should be sending it all to the cooler... A good vernatherm to me is one that is in the Lycoming standard straight oil filter adapter, not the right angle version. In the Lycoming unit, at least the vernatherm seat is machined as a unit. When you are dealing with two parts that are separate, as in the right angle versions, it still requires accurate alignment, and one of the parts has built in 'slop'... excuse me, but who's the genius that designed this???

Frank, another thing Larry discussed with me was optimum oil temperature. These engines are 'loose' compared to modern automotive piston engines (still neanderthal in my opinion), and as such, expand with heat to become a 'tight' engine. That expansion occurs at an oil temperature of about 195 (this according to Larry's extensive experience/testing). At that temperature(+/- a couple) your tolerance should be at it's zenith as far as getting the most our of your engine. Cooler oil - 180 for example - or hot oil - 200+, is not optimum. Your compression ratio is not what it should be to get the most available energy out of your expensive fuel. Your CHT's are dependant on your air cooling efficiency (baffles) to a certain degree, but also upon the amount of fuel that's being consumed. Your oil cools things off in addition to providing lubrication, but if it's too cool or too hot, your rings don't fit as tight and you loose compression. You get blow-by and that robs power and contaminates your oil. The ability to control the temperature of your oil has an effect on power, fuel efficiency, and engine life. Depending on a system (vernatherm) that has a built in 30% definciency doesn't seem like a good idea to me. Of course, you become the 'hall monitor' when it comes to maintaining safe oil temperature limits.

You know what they say YMMV.... well, I think your mileage will vary. Stay tuned,,,, I'll let you know what my 'mileage' is.

Click to expand...

Okay, the plunger (if installed) routes the oil around the vernatherm, taking it out of the equation. Looking at the pictures from Dan Horton and others I'm guessing that since I have the Lycoming (AC) filter adapter, I can install the spring and plunger and leave the vernatherm installed as the plunger does not interfere with it as on some of the aftermarket adapters. Correct? Or not? This would be an effort to eliminate the vernatherm as a source of high oil temps.

Mike,
Correct, assuming you have this adapter:

http://img12.imageshack.us/i/lycoilfilteradapter2.jpg/

Scott,
Sure it should work. I'm merely suggesting you carefully check fit and sealing of the plunger while you can still see though the bypass hole, before installing the oil filter adapter. If it doesn't seal, it won't work.

As for 195F being a optimum oil temp because of clearances between moving parts, consider two points.

When you apply the coefficient of thermal expansion (aprox 13 uin/in/F for aluminum and 6 for steel) to actual parts dimensions, what is the clearance variation for 15 degrees (say 180 vs 195)?

Which internal dimensions are actually controlled by oil temperature, vs combustion gas temperatures?

Dan,
I received the plunger & spring today and trial fit it. It fits snugly, just as designed and it will completely seal off the hole going to the vernatherm cavity. It doesn't really matter what kind of adapter you are using as it relates to the spring/plunger. They all use the same hole in the accessory case to interface with the oil filter and vernatherm. Lycoming has been using this spring/plunger since long before I started flying and I've been flying for a long time. There are also dozens of RV's with maybe thousands of hours flying with the system that I'm going to and it has worked very well for them for 25+ years, so I'm not exactly 'experimenting'. I wish I was the one that came up with this idea, but the credit goes to others.

Anyway, controlling your oil temp precisely is important for getting the most out of your engine. I'm not saying 195 is the perfect temperature (although there definately is one for each engine), but according to these others that have gone before me, there is an oil temperature where your engine tolerances achieve their ideal condition, the way it has been designed for more than 50 years, and at that point you as a pilot can feel it. And you can actually see it when you buy your gas and change your oil. Don't get me wrong, this isn't for everyone. It will take concerned attention from you as a pilot, but this is what I like to do. I'm constantly fiddling with my engine parameters while flying and I don't think I will forget that I'm responsible for controlling oil temperature. Those that prefer to 'set it and forget it', should stick with their vernatherm, no matter how inefficient. There's one thing for sure, the vernatherm is safe. That's why Lycoming came up with it. It's not as good as you are at controlling oil temperature, but it won't kill you. It'll just cost you more in the long run (and it's no fun). If any of you are running oil temps in the 240 range, I don't think eliminating the vernatherm will be enough. You should look to something else. Lycoming has a publication about dealing with high oil temps and they address several issues. If anyone is interested, let me know and I'll get the link, but I think I got it here on this website, so look around, and let me know if you need it.

My oil cooler should arrive tomorrow and I'm still waiting for some gaskets and other hardware, but I expect to be flying again soon. I've made a little 1/2" spacer to hold my oil cooler off the cylinder a little and allow more room for airflow. I also installed a little baffle that others have talked about to keep #4 cylinder exhaust fin air separate from oil cooler air. Seems like a good idea to me too. The manual system of control has not been finalized for my install yet, but I can still fly when I get my cooler (without the vernatherm) to see how it does. When I settle in on where to mount my shut-off valve and vernier control, I'll get some new hoses made and be in business. This is what homebuilding is all about. Flying, testing, experimenting,... maybe making things in your (my) application better. This is better than just raw building, although I miss that too.

Thanks for the input.

Scott Hersha said:

Dan, I received the plunger & spring today and trial fit it. It fits snugly, just as designed and it will completely seal off the hole going to the vernatherm cavity.

Click to expand...

Excellent. So did it turn out to be a plain cylinder or does it have a conical seat?

It doesn't really matter what kind of adapter you are using as it relates to the spring/plunger.

Click to expand...

True, but let's not confuse. The adapter itself doesn't matter, but the tip of a vernatherm seated in the accessory case hole may foul the plunger. Mike's AC adapter has it's own dedicated internal seat, so he can leave the vernatherm installed and install the spring/plunger too.

....it has worked very well for them for 25+ years, so I'm not exactly 'experimenting'.

Click to expand...

True. I was looking forward to hearing what sort of oil temp drop you got by eliminating the leaking vernatherm, but it sounds like you're changing coolers and cooler mounting at the same time. Three changes at the same time means no hard conclusion about any individual change.

BTW, I like the system because it allows shutting down all cooler flow in cold weather. Fact; a vernatherm system cannot do that.

There is a tapered seat on the plunger and there is a relief machined into it's cylindrical body all the way around a little above the seat with a hole drilled in it. Here's what that is for I think. That hole allows oil from the oil cooler to get into the plunger where the spring resides from the back side during normal operation through the passage that would contain the vernatherm if you had that instead. That allows the plunger to sense differential pressure - pre-oil cooler pump pressure and post cooler pressure (lower because of oil cooler pressure loss). When the plunger senses a great enough differential pressure - spring strenth determined - the plunger unseats to relieve this pressure and oil bypasses the cooler.

In Mike's case, I don't think you should leave the vernatherm in if you are going to use the bypass plunger. For one thing, I think the instructions says to remove the plunger and spring when you install the oil filter adapter. Check with Lycoming or the Service Instruction sheets, but I believe that's what it says. The reason the vernatherm doesn't interfere with the plunger the Lycoming AC adapter is because it is mounted parallel to the accessory face and the vernatherm seat is in the adapter. In the right angle adapter, the vernatherm is perpendicular to the accessory case the the bypass hole coming from the plunger cavity is actually the venatherm seat. If you use this adapter without a spacer, it's possible that the tip of the vernatherm could foul or make contact with the plunger. I'll check it out today when I go out to the airport, but it shouldn't matter. You don't use a bypass plunger assembly and a vernatherm at the same time. My vernatherm is removed and I can stick it it the hole (adapter is removed right now), and see if it hits the plunger body. The important thing to understand here though is with a bypass plunger and spring installed, the vernatherm could not operate. Oil can not go down that hole in the accessory case toward the cavity in the adapter, because the plunger prevents this - as designed. Could you use both with an AC adapter? Sure it would work, but the vernatherm would only be sensing oil coming from the cooler after it is cooled as it returns to the adapter through another entry to the vernatherm cavity into the filter. The vernatherm could swell and shrink all it wants, but it would do nothing because the oil cavity upstream (toward the pump) of the vernatherm tip is closed off by the plunger. The danger in this 'dual' arrangement is this (other than mechanical interference in the right angle version). Let's say the plunger sensed an overpressure in a warmed up engine and opened up to relieve this pressure. Where would this bypassed oil go? It would go down the bypass cavity toward the filter and run smack into the vernatherm tip which is closed down because it's warmed up. Now the pump pressure has to override two pressure relief devices to bypass the cooler. Remember the vernatherm is a temperature and pressure relief device. The plunger is also a temperature relief device, indirectly. It's also called a viscosity valve. When the oil is cold and thick, the resulting high pressure will unseat the plunger and bypass the cooler until the oil warms up and thins out and re-seats the plunger. This may not work as well with multi-viscosity oil. However, the bypass plungers rarely leak. Vernatherms are much more prone to leakage.

Mike, like I said, I don't think you should use both. Check with Lycoming, but even if it was OK, it would serve no purpose.

For my purpose, installing the spring/plunger assy is only for troubleshooting by eliminating the vernatherm from the flow path. If my oil temps are appreciably lower I would replace the vernitherm and remove the oil cooler bypass spring and plunger again. I did the "boil your vernatherm" trick and it lengthened at about 180 F but only by 1/8" or so. My engine had the oil pressure bypass/oil screen setup when I aquired it as a core. I added the Lycoming oil filter adapter and Superior vernitherm at overhaul. Many thanks to Scott and Dan for the inputs.

Mike,
Lycoming spec for vernitherm expansion is .160 minimum. If yours only goes 1/8 (.125), it probably isn't closing all the way.

I have been asked for some pictures of some of the parts for my oil cooler mod so here they are:



There is a couple pics of the bypass plunger/spring apart & assembled, vernatherm disassembled, and of a mod I made to move my new SW oil cooler off the #4 cylinder about .6". I also made a small baffle over the #4 cylinder fins to separate the cylinder cooling air near that exhaust vavle from the cooling air going through the cooler.

I'm waiting for new longer bolts to come from ACS before I can install the new cooler with the spacer. The ones I ordered and received weren't long enough - bad guess. I'll be installing the manual shut-off valve to the cooler, but won't have the control for it installed right away while waiting for the cable to arrive after figuring how long it needs to be. I'll also be making a new hose - a little shorter than the current one. I'll take some pictures when I get it all done and report on how it works.

Sometimes I forget how long a modification takes. There is nothing that you use (almost) that is available locally. Getting stuff shipped from all over the country, twice sometimes, takes a lot of time. The operating cable will take some creative modifications/installation and require a close guesstimate of the length, and I can fly with the valve full open for now with no problem. I won't need to restrict flow to the cooler for a while I don't think.

Thanks for the pictures Scott. Plunger doesn't look anything like the line drawing in the SB.

The hole in the relief groove vents the space above the plunger (the volume containing the spring). That space would eventually fill with oil, with or without the hole. However, without the hole that oil would be trapped and prevent the plunger from moving.....a hydraullic lock. Movement would be limited by leakdown rate in the bore clearance, likely too slow for response to a cooler pressure rise.

I really like the deflector/shield

The proximity of the oil cooler to the hot fins always concerned me. I saw a Mooney at Oshkosh last year that had a curved piece like yours blocking the radiant heat from going to the oil cooler. I think that is something I want to try too. The one on the Mooney came out farther over the cylinder though. Here are two pictures of it.





I moved my oil cooler back about 3/16" using aluminum plate and it did reduce temps a little, probably because of better air flow into the lower part of the cooler. I'd like to go even farther back but if I did that I might just change to mounting it on the firewall on the right side. It's tough to get it moved back or up very far on the -8.

I finished installing my new Stewart Warner 8406R oil cooler today and test flew it. I didn't install the oil shut-off valve yet, and don't know if I will. I have the airflow shutter from Van's that I never used, so I'll probably try that first when it gets cold out. I'm attaching a few photos, but if you've kept up with this thread, you have probably already seen most of them.

My takeoff OAT was 85 (& very humid) and I climbed directly to 8500' at 115 KIAS, which took 12 1/2 minutes with a reduced climb rate for a couple minutes to stay below a Class B. At top of climb, the OAT was down to 62 and my oil temperature was 185. Climb was done at full throttle and 2550 RPM. I began to lean at 5000' for smooth engine operation. 2 minutes after with the throttle still wide open, 2400 RPM, and mixture not leaned any more (about 14 gph), the oil temperature had stabilized at 181-182.

At 8500', WOT 21.6"/2400 runining ROP at 10gph, KTAS 181, OAT 64, the oil temp was 185.

Then I climbed to 9500 - I didn't touch the throttle or prop - just pulled the nose up and climbed 1000'. Leveling off, the OAT was 59, and oil temp had increased to 192. Numbers recorded at 9500:
WOT 21.0"/2400/69% power ROP, 9.5 gph. Oat 59/ oil temp 193/ KTAS 178.

Then I leaned it and got these results:
WOT 20.8/2400/ 64% power/ LOP, 7.8 gph. OAT 59/ oil temp 192/ KTAS 179.

I then descended to 3000' at 155-160 KIAS and 60% power. At level off the oil temp had cooled to 183 and the OAT had warmed to 75. Cruising along at 3000' for about 10-15 minutes, 62% power (21.5/2400) at 8.5 gph, my oil temp stabilized at 190.

All these numbers are between 15 & 20 degrees cooler than I was experiencing with my Niagra 20002A that came in my firewall forward kit. The major part of the improvement was due to the oil cooler change as comfirmed when I borrowed Jon Thocker's SW8406. I think the spacer in front of the cooler and the vernatherm removal had a small effect. The problem I have with the vernatherm on my installation (right angle adapter with spacer) is the inability to ensure an accurate line up of the vernatherm seat. The oil cooler spacer was used to improve airflow through the lower part of the cooler, but I don't think that had much effect on lowering temps - maybe some. What it did do that was noticeable is, my #4 cylinder was my hottest, now it's second from the coolest in the cruise configuration. During climb it's still the hottest, but by a small margin. I guess more of the air is getting directed down through the fins on the aft end because of that little metal baffle I put in.

This new oil cooler is just more efficient than the Niagra. With my Niagra, I would see cruise oil temps up high with OAT's in the 57 degree range, of 205 - 210. And when I descended, it didn't cool off any. By the time I got on the runway it would be up to around 217. I know this is not terrible, but I'm much more comfortable with what I'm seeing now. The hottest I've seen with my new cooler, after landing and taxiing to my hangar is 200 degrees. 3 flights doesn't prove it, but I think it's going to work out pretty good.

One other thing.... you know how when you change something, it affects several other things you didn't plan on? Well, I'm going to have to get or make at least one new hose, maybe both of them. Just moving my oil cooler back .6", my hoses come very close to interfereing with my oil filter, engine mount, and prop governor bracket. I've got them rigged for now, but I'll probably be replacing them for peace of mind.

Thanks for posting that Scott. So many times, people find solutions to their problems and don't let us know how it was resolved.

Sounds like your oil temps are about right for the current OAT. Probably come winter you may run a bit cool.