Oil Temp - M20E

[M20E-1964]

I'm flying a 64 M20E and think that perhaps the oil temp may be a bit high. My new to me A&P thinks its a bit high as well.

During nomal climb out... say 100 MPH maybe a bit faster, the oil temp gets to be one or two "needle widths" short of red line. Once at altitude it comes down and sits nicely in the middle of the green arc, maybe a tad higher than the middle.

At one point, three rows of fins on the oil cooler got flattened - probably by someone with a powerwasher (not me). The other rows are perfect. The flattened fins were straightened and are a lot better than flat, but not perfect.

A general inspection of the back of the oil cooler by the A&P find it to be in good shape.

The engine is a Pen Yan with 450 SMOH and is other wise in good shape.

 

Any thoughts? Is this normal? Not normal?

[xftrplt]

Hopefully, some reassurance:  I've found that the analog oil temp gauge, with its non-linear scale, in my 231 appears to read high when interprolated.  A digital reading of 185 degrees on the EI puts the analog within two needle widths of the RL.  I trust the EI, which indicates an accurate ambient temperature when the engine is cold.  You might consider a digital indicator such as http://www.aircraftspruce.com/catalog/inpages/ei-digitalgraphic2.php

[Immelman]

What does the gauge say when the engine has been sitting a while (i.e. same as ambient temp)?

I was concerned abourt mine as well until I realized that whether it was 30dF outside or 100dF outside and the engine (and oil) were "cool", that the gauge read 15-20dF higher than ambient.

[rorythedog]

Quote: gmcd

During nomal climb out... say 100 MPH maybe a bit faster, the oil temp gets to be one or two "needle widths" short of red line. Once at altitude it comes down and sits nicely in the middle of the green arc, maybe a tad higher than the middle.

[jetdriven]

You really should be seeing 110-120 KIAS in the climb. That and trailed cowl flaps really helps oil temps.  Ours never gets above cruise values like that.

[rorythedog]

Quote: jetdriven

You really should be seeing 110-120 KIAS in the climb. That and trailed cowl flaps really helps oil temps.  Ours never gets above cruise values like that.

[jetdriven]

110 KIAS gives 500-700 FPM down low, 500 at middle altitudes.   When not at gross, 120 KIAS is really almost the same.

[eaglebkh]

I often see a 100 degree oil temp diff between the JPI and analog gages - almost that much for CHT's.  JPI's are worth every penny IMHO...

[Jerry 5TJ]

I had a 64E for seven years and ~900 hours.  Oil temperature was not a problem on my airplane except once taking off at 8000' density altitude and 85F.  

Normal climb for me was 120 mph.   Vy is about 100 mph but the climb at 120 is "not much" worse and the cooling is better at the higher speed.    I habitually climbed that plane at 2500 / 25" power. 

Generally, and per POH, I had the cowl flaps open during climb.  I closed them at top of climb or on very cold winter days when oil temp fell below 160F.  

There was a plate installed on the inside of the cowl behind the oil cooler about 3" behind the fins.  The oil cooler was located on the lower left side of the front cowl bowl in its original location; some have been relocated.     That plate appeared to be designed to keep air from flowing from the bottom of the engine plenum and exiting through the oil cooler in the reverse of the expected direction.  You might check to see that (a) your plane should have that diflector plate and ( that it is in place. 

 

 

[Lood]

Anything in the green arc is fine and even one needle width below red line is probably between 200 - 220 deg.

[Newmooneyguy]

My 66 M20E has high oil temp with no apparent cause.  The oil cooler is new, and I still run 230 degrees at cruise with the engine leaned out.  I crack the cowl flap  and it runs around 215 or so, and I'm happy with that.

[M20E-1964]

I feel a little better now....

 

Flew yesterday where it was about 95 degrees in Florida.... at 3.5k it was hitting redline and bouncing into it every so oftern. The flight was only 20 minutes.... landed, everything was ok.

Took off at night.... a little cooler, and same thing.

Some folks mentioned JPI.... what is the consensius on pricing for the cheapest JPI solution w/ labor to install?

Hitting redline is making me nervous!

[Newmooneyguy]

It's quite possible that you have a gauge problem.  If your oil cooler looks normal and the pressure and CHT's are good, it's doubtful there's anything wrong.  My airplane had the engine analyzer added and although pricey I'm sure it's worth it.  I previously posted my oil temp behavior, it's a little high but I can live with it.

[takair]

My 64 E stays below 200 on the hottest Georgia days.  I typically see 180 to 190.  I did change the oil cooler due to mulitple bent fins and that helped keep temps less than 200.  Somebody mentioned the plate on the oil cooler.  I looked into that some time ago and it was for earlier Mooneys and was not required for the 64 Es.  My research indicated that it was to prevent the #2 exhaust stack from getting shock cooled and cracking and was not intended to help oil temp (but maybe it does).  I typically climb at 120mph with cowl flaps open.  You did mention that it bounced into the red, Newmooneyguy could be right about a gauge problem, my oil pressure needle is quite stable.  You could also have a simple wiring problem.  Basically, I think hitting the red is not normal for your plane, but it could be numerous things causing it.  Where are you located in FL?

[Lood]

My JPI EDM700 was the best investment I've ever made and should I ever, in the future, own and airplane without one, I will have one installed at once. The 700 is the basic model, but it does everything you need and more.

[M20E-1964]

I will say that the oil cooler does have bent fins. It looked like someone hit it with a power washer at some point. An overall inspection of the oiler cooler revealed that the cooler itself is find.

I did straightedn out a majority of the fins that appeared flattened. It's not pretty, but all fins are open. During the next oil change I do plan on having them replace the oil cooler.

It still just seems too high.

I think the JPI and a repalcement cooler will be done at some point in the near future.

[jetdriven]

A lot of guys on VAF replace their oil cooler for the same reason and almost every one reports no benefit.   Be sure to rule out all other possiblities. Such as the accuracy of that 48 year old gauge..

[takair]

I do agree with Byron, I mentioned changing mine and it got me only about 10 degrees. In my case that was all I wanted + the old cooler was quite ratty with previous repairs. Rule out everything else first.

[Lood]

I'm considering the oil cooler relocation mod. I've heard quite a few reports that this is much more effective in term of oil temperature than the original. Can anyone confirm this claim? I've had my oil cooler ultasonically cleaned and it was repainted with a heat conductive paint. Apparently to help dissapate the heat quicker and more effective. I don't really have problems with my oil temperature, but I don't like it being close to 220 deg most of the time. I would prefer it to be between 180 and 200. The old needle gauge can certainly be suspect, however.

[KSMooniac]

It sounds like you have the same situation as my 66E model.  The oil just runs hot for no reason.  At cruise after leaning I crack the cowl flaps and it stays around 210-220.  I don't worry about it. Maybe I should.

[M20E-1964]

Here's a question.   Are there any mods that can help oil cooling?  A better replacement oil cooler, multiple coolers?

Any lower cost cowl mods?

[rorythedog]

Quote: gmcd

Here's a question.   Are there any mods that can help oil cooling?  A better replacement oil cooler, multiple coolers?

Any lower cost cowl mods?

[M204ever]

You could check your vernatherm as well.

[danb35]

Quote: gmcd

Here's a question.   Are there any mods that can help oil cooling?  A better replacement oil cooler, multiple coolers?

[M20E-1964]

I was just reading about the oil cooler relocation kit but it looks like it's not available for 64's.