High oil temps

I bought a very well crafted RV-9a (032O carb Hartzell CS) with 80 hours on it about 3 months ago. I have flown it on a 5-hour roundtrip up to N. California and about 10 hours around the Corona area. The engine normally seems to run with an oil temperature of 200-210 degrees. Today, when I climbed thru 5,000 feet en route to Big Bear at 24/24, the temp was up to 245 degrees as I slowed my climb to 500 feet per minute. I then leveled for a minute and the temp remained around 240-245 degrees. I turned back to Corona, descended at low power settings and it seemed to cruise at 21/21 at 220 and 24/24 at 235 degrees at 4,000 feet. The OAT was around 89 degrees at 5,000 feet and the same down below. Is it OK to cruise or climb with the oil temperature at or a couple degrees below redline? What is a good max. cruise oil temp to use? The CHT were never over 375 degrees and the EGT were around 1350 and below even when the oil temps were near redline. Any thoughts or suggestions?

mdeland said:

... Is it OK to cruise or climb with the oil temperature at or a couple degrees below redline? What is a good max. cruise oil temp to use?

Click to expand...

Probably not on a regular basis.
We usually run 170-195.

May be worth checking to see if the sender/gauge are working right.

Yours is probably the first 9 I've heard of that has a high oil temperature problem. Most are just the opposite, can't get the oil temp up to 180 degrees.

What type of engine and how many hours? Does it have piston oil sqirters, that will raise your oil temperature? What type of mags do you have and are they properly timed? Do you have a Sam James cowl per chance, they tend to run a bit hotter until tweaked. I assume you have an oil cooler mounted on the back of the baffling; are you sure the previous owner did not have the cooler blocked off for winter flying? Are you confident your oil temperature gauge is accurate?

piston squirters

Based on the info you gave, I suspect that you have piston squirters in your engine. That takes a lot of heat out of the heads and puts it in the oil. I have the same problem in my IO540. The ultimate answer if all the other issues raised above are satisfied is a bigger cooler.

Gary Specketer

Probably doesn't have piston oil squirters... those are pretty much only in the realm of 360 engines, especially angle valve engines and ECI Titan Exp IO-360's. I've never heard of a carbureted O-320 with them. 245 is way too high, the oil is probably scorched now too since deep inside the engine it may get 20 degrees hotter than the temperature probe detects. That's really way high oil temps for a 320 engine. I'd suspect maybe not enough airflow or air pressure differential across the oil cooler. Maybe also might want to check to see if the vernatherm is closing and fully seating into its tapered port too. My carb'ed O-320 with Van's cowl on an RV-6 has difficulty getting the oil temps up high enough except in Texas summer heat.... something's definitely not going well with your setup.

Interesting phenomenon indeed. I am carbed O320 and max oil temp I can reach in prolonged climb is 180. Switch the probe maybe?

Not all rv9's run cold! Just today I was at 218f at 5000msl and 70% on 87f oat day, even tho I have to cover most of oil cooler in winter to get it up to 180f. Having said that, I also had a 394f cruise and 404f climb #3 CHT that I've been fighting, so my oil might be affected by that. Have about 85 hours on mine.

Still working thru things.

Had similar problem in my IO320-D2A RV9A with stock cowl
Interestingly enough the oil temp ran high until I turned the fuel pump off.
The G3X systems oil temp is uniquely influenced somehow by the fuel pump. Prior to coming to this conclusion I removed the temp probe and using a scientific thermometer I was able to test the probe at various temperatures starting at 250 degrees F. This checked out fine. I had a high oil temp and CHT while climbing out once at 85 kn and with 5 degrees flaps down. retracting the flaps all the way up solved the heat problem.

Thanks for the replies thus far; very helpful. I'll be looking at the vernatherm and the oil cooler and report back. Any other ideas or experiences are very welcome.

OIL TEMP

From MANY posts on this and other forums it appears that Positech coolers are the least effective and Stewart Warner the most effective with the others somewhere in between.

Mud Dauber maybe???

Sceliphron caementarium, the mud dauber.

Look in your scat tubes. A mechanic friend and I were doing an annual on my sweet bird 5 years ago. I noticed high oil temps on my first test flight. The thought of a mud dauber building a HUGE nest in the scat tube from plenum to oil cooler just didn't occur to us. We are talking about 2 days (prior to test flight) and us being with the plane most of the time.

We went on a very time consuming test of checking temp gauge, replacing vernotherm, etc. etc. ad nauseum. Then just by happenstance, I looked inside the scat tube and it was almost plugged completely!!!! We knocked out the nest, which by now had some very small pupae in the cells. We were shocked. Who would have "thunk" it!!! Replaced the cleaned tube, test flew it and no problems. Back to normal.

Now, I don't leave the plane more than 3 minutes without covering it. These pests are everywhere in south Texas. I have them trying to build a nest in my ear if I'm standing near the plane and don't move for 10 seconds.

Truly amazing. This probably is NOT your problem; but is an easy check. I now plug every hole, look in holes, etc. They build everywhere. I have a car in my hangar and noticed a nest on top of my driver's side front tire yesterday.

Not meaning to be a thread drift. It was a plugged airflow problem directly leading to my high oil temperatures.

Good luck!!!

One more thing - advanced ignition timing drives higher piston/head temps too. It is probably not the root cause, but this could be a contributor. Higher compression ratios, and advanced timing mean better SFC due to better expansion ratio of combustion gasses, but also drive higher temps on piston and head due to longer residence time in the cylinder, thus typical need for piston cooling jets.

My engine Matituck IO360 has now 65hTT and runs too hot.
I moved the cooler (Niagara 7 rows) from firewall to baffle and now back again to the firewall with a 4" scat and a SW different cooler. Also built a AL connection from SCAT to cooler to spread the air in all cooler superior surface. At 7800ft DA with 18ºC OAT the oil shows 106ºC (230F) in cruise at 53% ROP. CHT around 200ºC and EGT 740ºC. VAns not have any solution to solve problem. What can I do? some advice ? Practical please.
Where the cooler is will have enough depression to create a air stream? Is a defect of conception (design) of cowler?
Vanatherm valve is Ok. Gauges are OK.

Costa
RV7A Matituck IO360 M1B Hartzel CS Cimitar

Costa. In my RV-8 I had to go to the RV10 cooler setup on the firewall to get the oil temps in line. Bought all the parts from Van's.

Not sure what you have for engine monitor, but I know that Skyview has a couple different outputs based on the temperature sending unit you have installed. If you select the wrong one, it will display high oil temps...ask me how I know!

Make sure that no air can bypass the oil cooler. Use either RTV or "metal" tape to seal it.

Also, check the baffles to make sure there are no leaks. Look at inside of the top cowl, you should see rub marks where the baffles make contact. Any gaps in the mark indicate leaks. Also, all the baffles should be curved in towards the engine, not outward.

N941WR said:

Make sure that no air can bypass the oil cooler. Use either RTV or "metal" tape to seal it.

Also, check the baffles to make sure there are no leaks. Look at inside of the top cowl, you should see rub marks where the baffles make contact. Any gaps in the mark indicate leaks. Also, all the baffles should be curved in towards the engine, not outward.

Click to expand...

Don't forget to seal either the inner or the outer end of the inlet transition ramps that are epoxied to the upper cowl. Oh, and make sure those ramps are installed. Very important.

If you have tried every thing else, my vote is on the vernatherm. They all grow to different lengths at the same temp and they do age, (think thermistat in your car). Also check your vernatherm seat, they are sometimes re-cut slightly at overhaul and need a little longer vernatherm to seat completely. My AI buddy went thru 4 new ones until he got one that was long enough to seat and route the oil thru the cooler. Buy several with the option of returning the ones you don't need. Measure them cold then place them all in a pan of water and heat to boiling then measure hot. Obvisouly install the longest one, a few thousandths can make a world of difference. Dan

Thanks guys for your helps
Ramps: Yes they are there, a domes in front of upper cowl (inner surface correct?). Kyle talk about to seal the ends on inlet transition of ramps. Did not understand what talk about..
RV10 cooler ? How many raws have? 9? 11?
EMS: I have Skyview but first thing I checked was gauges. With probe in hot water comparing with thermometer Dynon read ok. At Once I introduced a thermometer inside oil sump and check against Dynon. was correct for temps under and above 100ºC.
Air by pass cooler. Bill I must use tape to seal what? Where exactly? Scat to cooler?
Baffles seems ok, rubber marks in upper cowl.Not seems to leak

A. Costa
RV7A IO360 Matituck
Light speed and magnet
Effis Skyview

guccidude1 said:

If you have tried every thing else, my vote is on the vernatherm. They all grow to different lengths at the same temp and they do age, (think thermistat in your car). Also check your vernatherm seat, they are sometimes re-cut slightly at overhaul and need a little longer vernatherm to seat completely. My AI buddy went thru 4 new ones until he got one that was long enough to seat and route the oil thru the cooler. Buy several with the option of returning the ones you don't need. Measure them cold then place them all in a pan of water and heat to boiling then measure hot. Obvisouly install the longest one, a few thousandths can make a world of difference. Dan

Click to expand...

First a checked the valve inside water. It expands.
The dome tip have marks like a ring, means the valve seat on hole.
After I changed for another vernatherm and was the same.
we can exclude the vernatherm and instal something that maintains the cooler route always open correct?

What kind of engine monitor are you running? Poor grounds can cause oil temps to read high on some setups. You can check for this by turning on things like landing lights or heated pitots and see if it changes the oil temp. Generally the effect is worse at higher oil temps so you can't just check for this on the ground right after engine start.

Flaps are built in airplane mostly for take off not for climb. Climb with flaps means a lot of drag. 85kts climb speed seems a low speed.