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Oil Temp

gen1313

Active Member
I finally have my RV-14 in the air. Aside from the excitement of the moment and the realisation of just how well it flew from the start I was paying close attention to temps. CHT's are great, nothing over 195C (385F) on climb and it is fairly hot here at the moment 35C (95F).
Oil temp on the other hand is higher than I would like. Regularly seeing 90C (195F) and up to 110C (230F). Anyone having similar experiences or any ideas?
 
Let me be the first to congratulate you Graham.
Big effort and commitment to get it finished so quickly. 👍
 
Australian Temps

My first 50 hours were conducted in outside temp of low to mid 80 degrees (Florida climate). My oil temps were consistently around 195 degrees. On sustained climbs I got high temps of 205 once or twice. I was hoping with the change out of run in oil to normal 100Wplus would see a slight decrease. Not the case.
I read an oil related article last week in Vans Airforce (forget exactly where), the author was technician. It was quoted the correct oil temp for Lycoming's was between 185 to 215. I don't think you have got a worry, as the engine frees up it should run a bit cooler.
My CHT's max out at 345 degrees and cruise at 310.
Hope this helps
Alan
 
I finally have my RV-14 in the air. Aside from the excitement of the moment and the realisation of just how well it flew from the start I was paying close attention to temps. CHT's are great, nothing over 195C (385F) on climb and it is fairly hot here at the moment 35C (95F).
Oil temp on the other hand is higher than I would like. Regularly seeing 90C (195F) and up to 110C (230F). Anyone having similar experiences or any ideas?

Graham,

You actually WANT your oil temp up there, especially given it will be lower in winter nd when the engine settles down.

Climb at around 120 knots IAS.

All the best.
 
Oil temp on the other hand is higher than I would like. Regularly seeing 90C (195F) and up to 110C (230F).

It was quoted the correct oil temp for Lycoming's was between 185 to 215. I don't think you have got a worry, as the engine frees up it should run a bit cooler.

I guess I'd be a bit worried seeing 230F on the oil temp. I had a friend with a Mustang II (O-360, Hartzell) that had a prop rpm runaway due to high oil temps...the oil got so thin that the governor couldn't keep the rpm under control and it went from 2400 rpm to over 3000 in just a couple seconds. Fortunately it all stayed together, but made for an exciting test flight.

Then there's the question of how good the lubrication is at 230 F...again, the oil is getting thinner and its lubricating qualities are going to be compromised at excessive temperatures, and at some point you could be seeing accelerated wear. I don't know what that point is, just saying that it's legitimate to be concerned about high oil temps.
 
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I guess I'd be a bit worried seeing 230F on the oil temp. I had a friend with a Mustang II (O-360, Hartzell) that had a prop rpm runaway due to high oil temps...the oil got so thin that the governor couldn't keep the rpm under control and it went from 2400 rpm to over 3000 in just a couple seconds. Fortunately it all stayed together, but made for an exciting test flight.

Then there's the question of how good the lubrication is at 230 F...again, the oil is getting thinner and its lubricating qualities are going to be compromised at excessive temperatures, and at some point you could be seeing accelerated wear. I don't know what that point is, just saying that it's legitimate to be concerned when the oil temp is that much higher than Lycoming's recommended 215 F limit.

Lycoming's redline is 245, IIRC.
 
Sounds like increased airflow or larger oil cooler for high ambient air temperature ops. 40deg+ Celsius is a common temperature for outback Australia. There is a slide restrictor for cooler months(cockpit adjustable)
 
Oil temp

Graham,

I recently had my IO-360 overhauled and had oil temps in the 195-230 range during the break in with mineral oil. After the engine break I changed the filter and switched the oil to Phillips XC 20W50 with Camgaurd and the temps are now stable at 185-195 in the summer.

As other guys have said, probably just a combination of a tight engine and using break in oil. Keep an eye on the temps and re-evaluate after engine break in. Then if it's still high look at the oil cooler location, airflow, exit area etc.

Oly
 
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CHT's are great, nothing over 195C (385F) on climb and it is fairly hot here at the moment 35C (95F).
Oil temp on the other hand is higher than I would like. Regularly seeing 90C (195F) and up to 110C (230F). Anyone having similar experiences or any ideas?

A few notes.

Lycoming's IO-390 operating manual is clear: Oil Temperature: The maximum permissible oil temperature is 235F. For maximum engine life, desired oil temperature is 180F.

Something over 200F during a slow climb is to be expected. Look at the oil cooler performance charts, and note how airflow affects cooling capacity. Pressure drives the flow. At 120 knots, available pressure is only half of that available at 170 knots.

It's often stated that an oil temperature of 212 or higher is desirable "to boil the water out of the oil". Actually, water evaporates just fine at room temperature; temperature increase just speeds the process. At 180F, the vapor pressure of water is about 30 times the pressure at 59F.

Boiling merely demonstrates that vapor pressure has exceeded local pressure at some location in the liquid. Local pressure drops with altitude, so boiling temperature at sea level isn't relevant anyway. At typical RV cruise altitudes (8500~11500) the boiling point of water is in the low 190's...not that it matters.

Higher overall CHT and oil temperature during break-in is to be expected. However, I suspect some seal and baffle work is in order. It seems to be part of the Phase 1 process for most builders. Here the forward governor doesn't help.

My oil temp sender indicates about 7F warmer than actual. If you look up the specs, the tolerance for those senders is really wide. Give yours a reality check.
 
A few notes.

Lycoming's IO-390 operating manual is clear: Oil Temperature: The maximum permissible oil temperature is 235F. For maximum engine life, desired oil temperature is 180F.

Something over 200F during a slow climb is to be expected. Look at the oil cooler performance charts, and note how airflow affects cooling capacity. Pressure drives the flow. At 120 knots, available pressure is only half of that available at 170 knots.

It's often stated that an oil temperature of 212 or higher is desirable "to boil the water out of the oil". Actually, water evaporates just fine at room temperature; temperature increase just speeds the process. At 180F, the vapor pressure of water is about 30 times the pressure at 59F.

Boiling merely demonstrates that vapor pressure has exceeded local pressure at some location in the liquid. Local pressure drops with altitude, so boiling temperature at sea level isn't relevant anyway. At typical RV cruise altitudes (8500~11500) the boiling point of water is in the low 190's...not that it matters.

Higher overall CHT and oil temperature during break-in is to be expected. However, I suspect some seal and baffle work is in order. It seems to be part of the Phase 1 process for most builders. Here the forward governor doesn't help.

My oil temp sender indicates about 7F warmer than actual. If you look up the specs, the tolerance for those senders is really wide. Give yours a reality check.

All good advice.

And I will add....

Being concerned about oil temp. (as long as it is not getting close to a critical value) on a brand new unbroken in engine is pointless.

Wait until the engine has at least 50 hrs on it and then re-evaluate.
 
390 engines have piston oil jets, right? If so, the high break in temps the piston sees is contributing to the oil temp. I'd expect things to settle down with more time on the engine. I've just added the cooling jets to my Rocket's 540 and anticipate some significantly higher temps on the first few flights.

Dan's point is worthy of repeating though. As often as these "poor cooling" threads pop up, the basics are often overlooked during the build process. Baffles need some special attention if you want the engine to cool effectively. And this includes the intercylinder baffles that are included with the engine. I've yet to run across factory installed intercylinder baffles that couldn't use some tightening up.
 
Thanks for the advice everyone. I think I'll just pay close attention not to exceed critical temps for now and reassess after I have a few hours on the plane.
Thanks again.
 
Hi Graham good to see you are flying. Did first engine start last Thursday. Working on the dreaded canopy. There are a few parts of this build that are challenging. Isn't this a great forum.
 
oil temps

Hi Graham
Just started flying XP400 with EFII ignition and fuel
With only 9 hours on the engine and mineral oil,
I'm seeing from about 189 to 203 but its winter here temps have been 25-45
but that doesn't seem to be the driving factor at this point.
I'm guessing i'm running into the Vernatherm cycling at this point.
I agree with the previous comments. fly the engine and give it a chance to break in, your temps are fine where they are at, but I too have a similar concern. Will continue to watch them. in the mean time what a flying machine:D:D
 
Hi Cliff, yes I do love this plane. Unfortunately we have had three weeks of weather consistently 100-110 degrees. If I'm careful I can keep the oil temps in the safe range under these extreme conditions so it should only improve from here. As much as I love flying my 14 it's not much fun when it 110 degrees outside:D
 
RV-14 and IO-390 in hot climates

Hi Guys
We get to 43deg C here in our Perth summers (Western Australia), I am hoping to be ready for first flight soon but summer is on its way so I read this thread and started to worry.
From what I read in this very interesting thread it seems that oil temps can get a little high with the IO-390 in the RV-14, but the comments here then go on to say that temps should be ok with stock setup.
Has anyone measured temps before any modifications and and then changed the stock oil cooler, modified baffles or fitted cowl flaps to their RV-14/IO-390 combination? And if so can they please share their experience and some temp data from this (please)?
Anti Splat do a cool electric cowl flap but id rather not fit cowl flaps unless its needed. For us now would be a good time to fit cowl flaps in the project build as next is painting. So some temp data for RV-14/IO-390 combo would be great please?

Has anyone tweaked their stock IO-390 baffles and improved temps that way, and can they please post some baffle tweaking tips?

Dave
S/N 140126
 
Hi Guys
We get to 43deg C here in our Perth summers (Western Australia), I am hoping to be ready for first flight soon but summer is on its way so I read this thread and started to worry.
From what I read in this very interesting thread it seems that oil temps can get a little high with the IO-390 in the RV-14, but the comments here then go on to say that temps should be ok with stock setup.
Has anyone measured temps before any modifications and and then changed the stock oil cooler, modified baffles or fitted cowl flaps to their RV-14/IO-390 combination? And if so can they please share their experience and some temp data from this (please)?
Anti Splat do a cool electric cowl flap but id rather not fit cowl flaps unless its needed. For us now would be a good time to fit cowl flaps in the project build as next is painting. So some temp data for RV-14/IO-390 combo would be great please?

Has anyone tweaked their stock IO-390 baffles and improved temps that way, and can they please post some baffle tweaking tips?

Dave
S/N 140126

Making mods before evening flying, or fully breaking in your engine is a waste of effort and cash.
As far as I am aware, RV-14's have been doing well with the standard baffle and cowl configuration in regards to temps.
The prototypes were both tested in temps just a couple degrees shy of 100F with a gross weight (at take-off) climb at Vy from 200 ft MSL to 10,000 on a standard temp laps rate day, without stopping. The CHT's topped out right around 400 and the oil temp topped out in the high 220's and then reversed in a downward trend midway through the climb (totally acceptable in those conditions for short duration flight).
Keep in mind this was at Vy (best rate) for the entire climb. Cruise climb at 120-130 Kts (makes sense in most situations since the ROC is reduced only slightly) and the temps will be noticeably lower.
 
I agree with Scott. Fly it first, then see what you have. I can say that my CHT's and oil temps on the RV-14 with the IO-390 are exactly what I would want. They really just never get too hot. I only wish that my IO-540 in the other plane was as perfect as this IO-390 is. That one the CHT's are great but I have to take care on oil temps during climb or on very hot days.

Fly it first, then worry later.
 
RVator OZ

I finally have my RV-14 in the air. Aside from the excitement of the moment and the realisation of just how well it flew from the start I was paying close attention to temps. CHT's are great, nothing over 195C (385F) on climb and it is fairly hot here at the moment 35C (95F).
Oil temp on the other hand is higher than I would like. Regularly seeing 90C (195F) and up to 110C (230F). Anyone having similar experiences or any ideas?

My I suggest installing EZ Cool Cowl Flaps from Anti Splat Aero which should increase the Plenum differential and move more air quicker over the Cylinder Heads and produce extra cooling. Iam fitting two cowl flaps to the underside of our cowl. Only use taxiing and for continuous climbs say to TOC 7000 ft at Vx or VY. They only weigh approx 7 ozs and are electrically operated. You can connect them together or use independently.
 
Oil Temp Issue Experience

RV-14A No.140363 flew for the first time on 6/14/2018. For the next two weeks I have been chasing down high oil and cylinder head temperatures. Three things were found. First was that the Garmin oil temperature sensor was so long it extended into the hole at the bottom of the cavity through which the oil is supposed to flow, thus reducing flow to the cooler. fixing this helped oil temp some, but not enough. Second was below spec fuel flow at full power of 17.5 GPH. The servo was sent back to AVStar and they adjusted the flow to 19.0. Third were mag issues. The left mag was at 22 degrees BTDC (instead of 20) and the right mag was 30+ degrees. The internal timing on the right mag had to be adjusted. Now both are at 20 degrees and the fuel flow at max power is 18.5 or better. During the last flight CHT was at or below 350 during full power climb and max oil temp was 208 (not terrific, but not bad for a new engine.) Since both the second and third things were done at the same time I'm sure the debate will rage on about which one solved the problem!!
 
Second was below spec fuel flow at full power of 17.5 GPH. The servo was sent back to AVStar and they adjusted the flow to 19.0.

Darn shame. 105 lbs per hour (17.5 GPH) is the correct spec (min fuel flow for rated HP). I lean mine in the climb from first power reduction. Airport is 200 feet MSL, and south Alabama can be as hot as anywhere.

Third were mag issues. The left mag was at 22 degrees BTDC (instead of 20) and the right mag was 30+ degrees. The internal timing on the right mag had to be adjusted. Now both are at 20 degrees

30 degrees will get it hot for sure. A dyno says 23 is a good all-around setting for a 390.

Since both the second and third things were done at the same time I'm sure the debate will rage on about which one solved the problem!!

No debate here.
 
Making mods before evening flying, or fully breaking in your engine is a waste of effort and cash.
As far as I am aware, RV-14's have been doing well with the standard baffle and cowl configuration in regards to temps.
The prototypes were both tested in temps just a couple degrees shy of 100F with a gross weight (at take-off) climb at Vy from 200 ft MSL to 10,000 on a standard temp laps rate day, without stopping. The CHT's topped out right around 400 and the oil temp topped out in the high 220's and then reversed in a downward trend midway through the climb (totally acceptable in those conditions for short duration flight).
Keep in mind this was at Vy (best rate) for the entire climb. Cruise climb at 120-130 Kts (makes sense in most situations since the ROC is reduced only slightly) and the temps will be noticeably lower.

What Scott has described here is a balanced heat rejection (therefore temps) for the engine and the oil paths. Since Vans has designed a pretty nicely balanced design for the inlets, a low CHT with high oil temperature balance would indicate that too much air is passing the engine side thus lowering the pressure on the top of the engine and lessening the air pressure for good oil cooling.

This would/will apply if the ignition timing is stock/correct.

Better cooling balance is a good item for the phase one investigation, but the high oil temps with short oil change periods should not be an immediate concern - at least not for temps reported.
 
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