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Oil temperature too high... Problem?

belisle

Registered User
Quebec, CANADA
When rebuilding my PA-12 I have installed a new nose bowl without an hole for the cooler and I changed the heavy oil cooler for an aluminum Harrisson model 8526250 and installed it at the rear of the #4 cylinder as per drawings of 337 forms that I had from the cub club. I had also the engine majored. Since that time the oil temperature is pretty hot on days above 80˚F. It shows 245˚ and over. I am still running with mineral oil. The oil pressure is in the green arc. So I checked the oil temperature gauge probe with an electric kettle and it was right on the 210˚ mark with boiling water. A friend that has an other oil cooler loan me his Niagara (20002A) cooler to check if it was the oil cooler and it made the same. I saw on this site that some guys have made a mod on their baffles to create a kind of venturi to increase the volume of air to pass through the oil cooler. I would like to know how to make this mod or find a drawing of it to fix my problem. Also I wonder if I change the oil for regular Aeroshell W100 if it will help to lower the temperature. Any comment, drawing or help will be appreciated. Please send your comment to my email address: belisleb@webnet.qc.ca even if you post them here.
Bernard
 
I'm not real familiar with that engine but, most aircraft engines with an oil cooler have a control valve to let oil to the oil cooler or to bypass the cooler. It's called a vernithane. That probably is not spelled correctly, but if you talk to your mechanic, he will know what you are talking about. It sounds like it is not opening at all in your situation.
 
Put your hand on the oil cooler. Can you hold it there very long??? If not then it's trying to do it's job.

Most Cub engines in earlier models just have the cold oil bypass and the oil is flowing through the cooler all the time (unless it's too thick and the bypass valve opens). With the Vernatherm the oil only goes to the cooler after it's up to heat (usually 180*F)...so if you have a vernatherm and your cooler is cold...while you engine is 245*F + then your vernatherm is cooked.

You say you just had the engine overhauled. Did the case get line bored by say ECI? If so did they remember to counter bore the bearing dowel pin holes the same amount that they took off the case??? If not they tend to hold the bearings like brake shoes and generate nice high temps like you are seeing. :bad-words:

Good luck,
Wayne
 
245 degrees with an 80 degree OAT sounds like another problem other than oil cooler to close to the cylinder to me. I will e-mail you pics of my oil cooler install but I would check that vernitherm/by-pass valve too.
 
Bernard

A while back I read that high oil temps can be caused by high oil levels statement said 8qrts would be consodered high. I have no idea why this would be but the statment said reduce your oil level to 7qrts and oil temps will be reduced. Might want to give it a try and see if that helps. Let us know the results

Cub_Driver
 
I had a similar situation recently. Temps were up above 235 on a 60 degree day. After checking the oil screen and finding no metal, I thought we'd try the cheap fixes first. Took the oil cooler over to Atlee's and had him solvent flush it for 24 hrs (function checked okay).

Removed the oil temp bypass valve and noticed that it was scored (as was the seat). Figured that this prevented the oil from getting to the cooler since it wouldn't seat properly. We replaced the screen assembly with a remote filter (airwolf) assembly and a new vernitherm. Temps now are around 195-205 in slow speed climbs at 60-65 degree days. Seems to have solved the problem.

I understand that you can recut the existing bypass valve seat and replace the bypass valve while retaining the screen assembly and accomplish essentially the same thing, but I also wanted to be able to change the oil a little easier so I opted for the replacement filter setup. Since I'm not an A&P, the job was done by a pretty skookum mechanic who apparently got it right.
 
cub_driver said:
Bernard

A while back I read that high oil temps can be caused by high oil levels statement said 8qrts would be consodered high. I have no idea why this would be but the statment said reduce your oil level to 7qrts and oil temps will be reduced. Might want to give it a try and see if that helps. Let us know the results

Cub_Driver

From my experience I think the opposite would be true, As if you have less oil you have less volume of oil to distribute the heat. I don't have scientific proof of this but I have see what appears to be this scenario on larger engines IO-540's that can be MAX 12 Qts Min 2-3 Qts(not that I ever went below 9) The temps definitely ran cooler at 11-12 Qts than at 9-10 Qts...

If I'm wrong I'd like to know this too...Any Engine Guru's have any comments???

David.
 
To answer to some of you who gave advices or recommendations I have other information for you. For David and Cub Driver: I keep no more than 6 quarts of oil in the engine, between 4 ½ to 6 quarts. Steeve: This engine does not have a Vernatherm. It is a 0-320A2B with the oil temperature sensor that goes straight in the center of the strainer cover. I would appreciate that you send me your pictures of the installation. Wayne : The oil cooler makes its job because it comes very hot. I will check with the overhauler if the case has been line bored and will come back to you. An other guy suggested me to install a second oil cooler below the cylindet #1 in series with the other, but he has an homebuilt so I do not know if it could be approved.
Bernard
 
Bernard,

Years ago, I had a Cub which ran really hot. It was a 400 hour engine since "major overhaul". We checked everything we could think of, and finally called Lycoming. They recommended running an automotive type compression test on the engine.

Turns out two cylinders had really bad blow-by, hence elevating oil temps.

It also turns out that the "overhaul" on that engine, to be concise, wasn't.

I hope this isn't your problem, but you may want to run an automotive compression test on the engine to see if the rings are seated, etc.

MTV
 
If you can get a few old instruments to check your airflow either an airspeed indicator for the top baffle area in front of the oil cooler and an altimeter for behind it, route the lines into the cabin and fly. Behind the baffles you should have a negative pressure, low altimeter reading, and positive pressure in front, airspeed indication. your new cowling may not be sealing correctly to allow flow through the oil cooler.
 
belisle said:
When rebuilding my PA-12 I have installed a new nose bowl without an hole for the cooler and I changed the heavy oil cooler for an aluminum Harrisson model 8526250 and installed it at the rear. A friend that has an other oil cooler loan me his Niagara (20002A) cooler to check if it was the oil cooler and it made the same.

A friend had one overhauled by Mattituck and it ran extremely hot. Put a new aluminum cooler in the front and it still ran hot. Tried everything they could think of including trying to get Mattituck to do something about it. They just told him to run it a little longer first. After a little while it quit running so hot.
I put an aluminum cooler in the back baffle of one once and never could get it to run cool. Sure was nice in the winter though. I think I was using the narrower one. Make sure you have the wide one. (Diggler knows which model that is, but since he ain't here no mo, you are one your own to figure out which is which). I'm sure somebody on here knows what part number the wider one is.
 
S2D said:
belisle said:
When rebuilding my PA-12 I have installed a new nose bowl without an hole for the cooler and I changed the heavy oil cooler for an aluminum Harrisson model 8526250 and installed it at the rear. A friend that has an other oil cooler loan me his Niagara (20002A) cooler to check if it was the oil cooler and it made the same.

A friend had one overhauled by Mattituck and it ran extremely hot. Put a new aluminum cooler in the front and it still ran hot. Tried everything they could think of including trying to get Mattituck to do something about it. They just told him to run it a little longer first. After a little while it quit running so hot.
I put an aluminum cooler in the back baffle of one once and never could get it to run cool. Sure was nice in the winter though. I think I was using the narrower one. Make sure you have the wide one. (Diggler knows which model that is, but since he ain't here no mo, you are one your own to figure out which is which). I'm sure somebody on here knows what part number the wider one is.

The standard size sold for the O-320's is the 20002A metioned above. The next size up is just one number higher 20003A and does a better job....but is it "approved" for your installation might be another question... that I can't answer.

Wayne
 
The cylinders they put when it has been overhauled were standard steel. I would just like try to put the oil cooler a little more aft of the baffles. Just waiting for the drawings or dimensions of the installation of Steve Pierce.
Bernard
 
Sent you a pic. The idea as I have been told is to move the cooler back off of the rear cylinder to create a venuri effect. We did some pressure checks with an airspeed indicator to verify the proper pressure differential between the intake (cylinder) side of the oil cooler and the exhaust side. Niagra gave me the pressure differences but I don't remember off the top of my head.
 
sometimes after breakin the temps come down alot and the worry is over. you may want to wait before drastic measures. run with full oil. do the compression checks to try to track the condition of your rings. next try 20-50 weight to see if that helps, as i suppose you have enough hours to have it broken in. good luck as these things are trail and error at your expense.
 
In a relatively dark hanger put a drop light behind the engine so you can see and evaluate the engine baffle. Take high temp silicone rubber and neatly seal the top baffle at the case and every other little crack that would make sense to seal. For baffle seal you can't beat RAM for there 3 inch reinforced. There's no substitute for a perfect baffle job. I don't aggree with high break in temps. Maybe 10 degrees, but more times than not my engines ran cool and normal right from the get go. Lycoming will more than likely tell you the same thing.
 
Yep, they'll run a little warm during break in, but not that hot, and only for a few hours at most.

MTV
 
Baffel

I agree with FORTYSIX 12. Make the silicon baffle material a little long so it rolls forward around the back baffle and into the center on the cylinder baffles with the side cowls closed. This way when the air comes through the nose bowl openings it will press the baffles even tighter closed against the cowlings. You first and foremost want a lot of air going through the oil cooler and cylinders. Loose fitting or floppy (looks good on the ground but lays back at air speed) baffles will cause a lot of problems. Crash
 
Thank you Steeve for your photos. For the baffle seals I used felt 1/2 thick and already check for leaks with a light and sealed all tiny holes when I rebuilt the bird. I will fly it again today to see if it still comes as hot. I have a 100 mile run to go and the day is supposed to be cooler + or - 60 deg. When back I will post the results. If it still too hot I will make the mod by changing the position of the cooler 2 inches more aft of the cylinder.
Bernard
 
The only other thing I haven't seen mentioned is if this engine was a recent overhaul make sure the inner-cylinder baffles were reinstalled correctly. That would change the airflow drastically and not allow flow through the cooler.
 
Back from the fishing trip

I made the trip and the oil temperature did not go over 220 deg. but the OAT was around 55. On my way back I run the engine at 2400 RPM instead of the 2350 I was running before and the temperature stayed below 220. As long as it will stay inside the green arc I will wait to make the baffle mod. I was with my son and we were fully loaded up to the top of the compartment but a lot lighter on the way back. Fishing results: one 11 inches rainbow trout :oops: taken by my son Jeff. This is a true fishing story!!!
Bernard
 
Bernard,

It is my opionion that you still have a fundamental problem with something that has been done to your airplane. Differential cooling pressure, bad or woreout parts, something.
 
Interesting, unless I missed it, no one has mentioned what the normal or expected opertaion oil temperature range is.

The green arc on the oil temp gauge is probably the most liberal interpretation of acceptable operating range.

As I recall, Lycoming suggests a minimum of 180 degrees for most of it's 0320 engines. Don't recall the high limit.

For my engine, I like to see it between 190 and 220 but sometimes operate 10 degrees above or 20 degrees below this. On the high end, I typically run full rich and even use carb heat to make the engine run cooler.

Heavy loads, bore props, tundra tires, steps, antennas, external tanks, cargo pods lumber racks and floats all slow the plane and reduce engine cooling.
 
high oil temp

Please continue to post ideas about solving this problem. MY PLANE HAS THE SAME PROBLEM AND I CAN'T SEEM TO SOLVE IT.

thanks for all the impute so far...jim
 
I suspect my old cub had a vernatherm problem/cooling related. Was real interested in the work Dave Caulkins did on Mike's Cub. Ursa Major explained it in a post above. Hey Mike---is it still cooling for you and have you finalized to your satisfaction that it was the vernatherm. Got to meet Dave the other day finally. Pretty sharp mech I believe.

Mark
 
Compression check

When making my annual yesterday we proceed to a compression check and all cylinders were over 75 on 80. I will install the mod for giving about 2 inches of space between the oil cooler and the #4 cylinder. Will keep you inform about the results.
Bernard
 
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