Oil temperature too high... Problem?

[belisle]

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

[J3-float]

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.

[Greg Smith]

Vernitherm. :wink:

[irishfield]

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

[Steve Pierce]

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.

[cub_driver]

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

[Ursa Major]

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.

[CaptFox]

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.

[belisle]

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

[mvivion]

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

[Cimarron]

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.

[S2D]

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.

[irishfield]

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

[cobblemaster]

I was wondering if you had chrome cylinders or not?

[belisle]

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

[Steve Pierce]

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.

[flyer]

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.

[Fortysix12]

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.

[mvivion]

Yep, they'll run a little warm during break in, but not that hot, and only for a few hours at most.

MTV

[Crash]

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

[belisle]

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

[Cimarron]

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.

[belisle]

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

[Fortysix12]

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.

[cubdriver]

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.

[klm_ak]

Cubdriver-on my STC it shows 120-245 as the green arc and 245 as the maximum.

[Jim Guldi]

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

[AkPA/18]

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

[cubdriver]

Do all Supercubs have a varitherm? How do you adjust it?

[belisle]

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

[Jim Guldi]

Varitherm this device is designed to open at 80 degrees centgrade it allows oil to folw ti the oil filter

[Ursa Major]

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

Mark,

Its still running right around 200 degrees but I haven't had the chance to fly it at much more than 65 degrees OAT. The forecast for this weekend looks like high 70s or low 80s. I'll see what kind of temps I get with low speed climbs.

We did a couple of different things including changing the vernatherm. Not sure if that was the cure. The installation of a remote oil filter probably helped too. I'm not too concerned with the temps we get up here - but I might be a little leery if I lived in Arizona or Oklahoma and had to deal with 100+ OAT temps.

[belisle]

I have installed the oil cooler at 3 inches aft of its previous position at the back of the #4 cylinder. I made a couple of flight since that time and notice that the oil temp was at 225 to 230 deg. while the OAT was indicating 58 to 60 at 2500 ft. The temperature was in the green arc of my gauge where the limit is at 245. I would prefer to have it lower around 200 to 210 but I still do not know what to do to lower this oil temp. I run the engine at 2350 with a Borer prop 82/43 and EDO 2000 floats. Indicated airspeed 80 mph at full gross weight. Any help will be appreciated.
Bernard.

[Steve Pierce]

If it were me I would get a 62417 oil cooler bypass plug, 69436 oil cooler bypass spring and a 62415 oil cooler bypass plunger and replace the vernitherm with these parts. They will let the oil through the cooler as soon as it gets warm enough to thin out. You should not have that high of an oil temp with those OATs. It has to be an engine problem or oil delivery through the cooler. I will see if I still have the above parts if needed.

[belisle]

Steeve: I was told by the engine shop that I do not have any vernitherm on this engine. The change on the position of the cooler (3 in. aft of the cylinder) did not change very much the temperature. Could you tell me what is the size of the holes on the nose bowl. When rebuilding the bird I change it for an other one (used but in better condition than mine) and I am not sure for what model of Piper it was coming from. I had to adapt it to the cowlings with some adjustments. Maybe the holes are smaller than the required ones??
Bernard

[skysigns]

if it helps piper had a #SB about using 2 coolers the panwee 150 installed one under the right front baffling as well is in the nose bowl varitherm in some of the older 0320 was a spring and ball that pushed a sleave the sleave might be sticking on your bottom cowl you can existent the lip about 2" to draw more air threw the cowling i have a 12 i am rebuilding now that has the same problem it stays on floats i should have it flying in the spring let me know how yours comes out

[StewartB]

Light Plane Maintenance had an interesting article about high oil temps a couple of months ago. They mentioned the normal things, like baffles, incorrectly seating Vernatherms, etc. One case they discussed was caused by insufficient bearing clearances. The oil cooler couldn't overcome the increased heat caused by reduced oil flow (not oil pressure) and tight bearings. The engine was torn-down and the bearing clearances corrected, and the problem went away.

Who did your major, and did they check the clearances? Make sure you're treating the problem, not just the symptoms.

SB

[Fortysix12]

Vernatherms close to do there job not open. That's why they need to be 100 percent and varified. Visually. And changing one used one with with a another used one can be a waste of time. When trouble shooting oil temps you have to varify with absolute certainty that all parts are doing there job. No exceptions! This means observing the full function of the part closing and opening in a pot of boiling water installed in the oil filter adapter. I have had a brand new therm not function.

[cubdriver]

AGAIN, DO ALL SUPERCUBS HAVE A VAIRTHERM??

[T.J.]

NO!

[leon tallman]

I think your problem is that prop. the 172's have the same engine and oil cooler the citarbia's also and no problem the diff is about 20 to 30 mph in airspeed. so you don't get the same airflow. i hope you get this worked out as I have the same problem. i'll be watching

[mvivion]

The problem isn't the prop. And he said he doesn't have a vernatherm. As someone pointed out, that is way too hot an oil temp for a Cub, even if you had a different nose cowl. Remember, virtually all the Pipers had similar sized engines, so the air inlets should be just fine.

Are your cylinder head temps high as well?

As advised, I'd start taking a close look at the engine's internal working parts. As Stewart noted, you may be trying to treat the symptoms, instead of the problem.

In temps that you describe, on floats, I expect to see oil temps running around 170 to 180 F. Your temps sound WAY too high, and I doubt it's the cooler causing the whole problem.

Get a good wrench to start looking carefully at your engine. There could be something wrong in there that could cost you a lot if left unresolved.

MTV

[mvivion]

Bernard,

Oh, yeah: I just noted that your mechanic did a differential compression check on your cylinders. What I had recommended is an AUTOMOTIVE compression test. This test is recommended by Lycoming for trouble shooting cylinder problems, and used to be pretty standard, but lately has been replaced by the differential test.

The differential test only tests the cylinder's ability to HOLD pressure at one spot in its' stroke. The Automotive compression test, on the other hand, evaluates the cylinder's ability to MAKE compression, not hold pressure. That is a very fundamental difference.

My engine which I learned this on was running very high oil temps, in the range that you list: 230 or so, even on cool days. Cylinder head temps were over 400 as well, but well under red line. We couldn't find any problems on this 400 hour engine.

Finally called Lycoming and they said to do the automotive test. Two cylinders were allowing severe blow-by, heating the oil. This also results in pretty black oil pretty fast.

There's one more possibility that nobody has listed yet. I don't have my Lycoming books here, but if that engine is one that has had a constant speed propeller on it at some time, it is possible that when they removed the prop governor, they didn't put the plugs in where they should have. That's a long shot, but I've seen two Cubs (both sold rebuilt by the same company) which had engines removed from a Twin Comanche. The outfit had rebuilt the engines, but didn't make the appropriate changes to accomodate the removal of the prop governor. This bypasses the oil from parts of the engine and causes oil temperatures in the range you describe.

Ask your mechanic to check to verify that your engine does not have a provision for a governor. If it does, this is a possibility, and the engine oil temps will run pretty hot, since the oil isn't circulating properly.

MTV

[StewartB]

Here's something to read. Not the LPM article I referred to, but similar.

http://www.avweb.com/news/maint/182617-1.html

SB

[belisle]

I have called Lycoming and explained my problem and the technician told me that if the oil temperature was in the range of 230 to 245 and over and the oil pressure was in the green arc from 50 to 85 psi the problem would certainly be at the gauge. Even if the gauge was looking to be OK with boiling water he told me that it had already happend that in the high range it could be defective. He told me also that when the oil temperature is going higher the oil pressure is going lower as much as 20 psi and in the yellow arc. He told me to use an infrared heat temperature gun and direct it on the oil pressure screen near the magnetos just after landing to check if the temperature would be about the same + or - 5 degrees by comparison with the gauge. I have read the article posted by Stewartb on avweb and I will double check everything they suggest to do. The technician also told me that the magic number for the oil temperature was 220 degrees.
Bernard

[mvivion]

Bernard,

The technician is correct on 220 being the "optimal" temperature, perhaps, but you'll not see a lot of Super Cub installations that run that temperature, unless the OAT is screaming hot.

MTV

[cubdriver]

If you consider 75 to 80 F as screeming hot, I agree.

Continous operation at 170 F sounds too low, espically on floats.

[teeweed]

I have a 1958 P.A. 18 with a 0-320 A2B. The guy I had purchased the plane from installed a second oil cooler that hangs down past the air ductwork. I don't like the looks of it but, it does keep the oil temps good, even on the hottest days down here in Houston Texas. I fly slow and low for long periods of time, so this set up works good for me. In cold weather I have to restrick the cooler with a tin wrap, and on the coldest days sometimes I place a small amont of tape on the front cooler also. I do this to get the temps up to take care of any moisture build up. It's a quessing game that I dont like to do. We have only a few really cold days down here, so I put up with the hassel and the looks of the cooler hanging down past the airbreather. Mark

[wdbrown]

Maybe a help? Bought a new cub in late 70's to tow sailplanes. Ran fine from Lockhaven to Colorado Springs where Dave Johnson (now deceased) changed engine to new 0-360 and new prop. Tons of overheating problems. Dave pulled every hair out. Redid baffles and a bunch of other cooling tricks. Rabbit stayed in the hat. Lycoming said it was just tight and to use it. We tried but it really ran hot towing...imagine that! Final solution was in the engine. Calls to Lycoming got yawns because the hicks out in the boonies didn't understand engines. Finally friend and fellow pilot, not to mention attorney, called them and made our position clear. They sent a new engine and it ran cool. Very cool as a result of all the excellent baffle and other work done by Dave Johnson. Finally, a call to a friend 'inside' Lycoming revealed they had installed the wrong or improperly installed (we never found out) the camshaft. Just a thought, check the engine.

[Fortysix12]

Maybe a help? Bought a new cub in late 70's to tow sailplanes. Ran fine from Lockhaven to Colorado Springs where Dave Johnson (now deceased) changed engine to new 0-360 and new prop. Tons of overheating problems. Dave pulled every hair out. Redid baffles and a bunch of other cooling tricks. Rabbit stayed in the hat. Lycoming said it was just tight and to use it. We tried but it really ran hot towing...imagine that! Final solution was in the engine. Calls to Lycoming got yawns because the hicks out in the boonies didn't understand engines. Finally friend and fellow pilot, not to mention attorney, called them and made our position clear. They sent a new engine and it ran cool. Very cool as a result of all the excellent baffle and other work done by Dave Johnson. Finally, a call to a friend 'inside' Lycoming revealed they had installed the wrong or improperly installed (we never found out) the camshaft. Just a thought, check the engine.

Makes good sense good information to know.

[andres2249]

How can the factory install a wrong cam? how can it even fit? incredible but true wow..........................................andre s

[belisle]

One of my friends bought a PA-12 project and when looking at it I noticed that his bottom cowling was different than mine. He had a curved lip on the aft part of it. So I made a wood form as a pattern and modify my cowling to the same as his. The temperature dropped for at least 20 degrees and fixed the high oil temperature problem. I think that is creating more vacuum to exit the hot air from the engine compartment. Thanks to all of you who gave me tips to fix my hot oil temp problem
Bernard