‘65 M20E fighting High Oil Temps

[Jvharps]

preface - I am a new mooney Pilot/owner, I may miss some details here but, I can elaborate to my best. I am really hoping to resolve this. I have read several threads on this and I’m not sure if the next steps. Hoping someone may have a similar situation that has been resolved. 
 

back ground, I purchased the plane a little over a month ago. Flew the plane and noticed high oil temps on the OEM gauge. I made it up to 10,500 and cruised it back home from AZ to CA. I did notice the gauge was at the top of the oil temp green range most of the flight and added it to my Squawk List to have my mechanic review when I was able. There was no Oil T probe for the JPI 730 at purchase.  Outside of that, everything else was fine: EGT’s/CHT’s/Oil Pressure all great. Cowl flaps: open. 
 

when I got it home I took it straight to my IA for a through review. We (In order) tested the oil Temp gauge(questionable), tested the oil probe, checked the vernatherm(the seated position was in question by the shop) checked the vernatherm and it opened per the specs, flushed the oil cooler. I was finally able to test fly it after the CA fire Smoke cleared for a day or two, no luck still hot.
 

So I had the JPI 730 oil T prob installed for a check as a backup and sanity check to the analog gauge. I test flew it again. 
 

Settings: climb out (120 mph) to 6,500 MSL it got up to 215*. Short Cruise 5-10mins: 2400 rpm 21” MP Oil Temp hovered around 199-205  on the JPI. OAT approximately 75 degrees F

 

today I flew for my Flight Review and some final transition training. We were at 6,500 msl for an hour. While at alt the power settings where at 2400/24” - temps soared to 231*, OAT 67 degrees F. I pulled back to 21” MP opened the colw flaps and left the CHT’s alone as they where at 1375, thereabouts - Oil Temps came back to about 210* 

Anythoughts on next steps? I looked into the oil cooler relocation STC from LASAR but it states Non-dog house baffles and 1967 and newer so, that’s out. 

I read this thread in full and tried almost all

 

thanks for your time and help! 
 

Vince 

 

 

 

 

 

[Ragsf15e]

I’m not gonna have a solution for you, but a few questions that might help us... how are the CHTs at cruise?  How are you leaning?  Rich of peak lean of peak, peak?  And how much rop or lop?  Do you have the metal “heat shield” on top of the lines to the oil cooler?  What about the one behind the oil cooler?  Are the mags timed correctly, recently checked?  I can see my oil temp go up some as my Surefly advances and my CHTs go up a bit.  **raw egt numbers aren’t going to help us much, but CHTs might, what temps are they in climb and cruise?  Are they relatively even, are the egts relatively even?

Just FYI, the OATs you stated are pretty warm at altitude.  190s in cruise oil temp wouldn’t be a surprise.  The higher oil temps in climb or maybe doing maneuvers on your flight review can happen if you’re not rich enough and slow down (like for slow flight).  You will see the CHTs rise and then the oil temp is pretty quickly behind them.  

[takair]

Which model Mooney do you have?  As Rags suggested, what are the CHTs running at, you said normal, but are they below 380?  Old Mooneys are very finicky about cooling.  You want ALL of the air going through either the cylinders or the oil cooler. If air is going past those through leaks, cracks, etc. It is stealing from the ability to cool the heads and the oil.  While the cowl opening is huge, airflow is limited by the cowl flap opening.  If air is bypassing the things that need cooling, it is the path of least resistance out the cowl flap and limited air through the oil cooler.  Have your mechanic look really close at all opportunities for air to escape these areas.  It can be time consuming, but worthwhile.  Other things to look at are mag timing, but CHT is usually a give away there.

[carusoam]

Welcome aboard jvh.

How technical are you?

You have been doing some reading...

Lets see if you missed anything...
 

1) Oil absorbs much of the heat generated by the engine...

2) It dumps this heat using the oil cooler...

3) The vernatherm starts off closed open, and opens closes, as the oil warms up... as it opens, it sends oil to the oil cooler...  (See Rich below for the correction) 

4) Oil coolers stop working after a while...

• They get dirty on the outside
• They get dirty on the inside
• They get their fins crushed by unknowing owners
• They get mis-plumbed as we have seen around here lately

5) To know how well your oil cooler is working (Not working) it doesn’t take much more than an IR thermometer from HF....

6) If you are Seriously concerned about the oil flow through the oil cooler... there is a simple method to check all the hoses and wash things out...

7) It simply could have a lot of sludge in the bottom of everything...

8) Instrument accuracy... make sure the oil temp gauge is telling the truth...

9) 205°F in Cruise sounds pretty normal to me...

10) The needle should always be within the green arc after T/O...

11) verify you have the right part number on your vernatherm... It is easy for the unknowing to replace it improperly...

12) very often dog houses leak precious cooling air... baffle seals can be equally leaky...

First thing you want to do... Is add some detail about you and your plane... it is called the avatar area... if you are using a small screen it will be more challenging to do...

It is hard to solve problems when we don’t even know what plane you are flying... or where you are flying it... (the title is a good place temporarily, realistically, who’s memory is that strong by the time you have gone down the page...

It is kind of odd you haven’t mentioned what your transition trainer has said about the challenge... Expect that he knows a bit more about this plane than you...

PICs are the next best thing... if you don’t have an engine monitor supplying data use your cellphone... capture some pics...

Best regards,

-a-

 

[N201MKTurbo]

Actually, I think Vernatherms start out open and close the oil cooler bypass port when they heat up.

[N201MKTurbo]

You might want to inspect the vernatherm seat. I resurfaced mine once and it did improve the oil temps, not an earth shattering change but maybe 5 deg better.

[MikeOH]

My '70 F oil temp runs hotter than I'd like, but better since I redid the baffles (I had high CHTs, as well.  Ran into the low 400s before I fixed the baffles).  CHTs run 320-350 now, even on hot days.  I do run LOP.

OIl temp is still around 215-220 in cruise, and can get to 230 in climb on a hot day.  I've had the oil cooler overhauled by Pacific OIl Coolers (not just flushed), replaced the oil lines to/from the cooler, checked the vernatherm and its seat...

I've just learned to live with it.  The factory gauge never gets past the green, but it teeters on the edge sometimes!

[Jvharps]

12 hours ago, Jvharps said:

preface - I am a new mooney Pilot/owner, I may miss some details here but, I can elaborate to my best. I am really hoping to resolve this. I have read several threads on this and I’m not sure if the next steps. Hoping someone may have a similar situation that has been resolved. 
 

back ground, I purchased the plane a little over a month ago. Flew the plane and noticed high oil temps on the OEM gauge. I made it up to 10,500 and cruised it back home from AZ to CA. I did notice the gauge was at the top of the oil temp green range most of the flight and added it to my Squawk List to have my mechanic review when I was able. There was no Oil T probe for the JPI 730 at purchase.  Outside of that, everything else was fine: EGT’s/CHT’s/Oil Pressure all great. Cowl flaps: open. 
 

when I got it home I took it straight to my IA for a through review. We (In order) tested the oil Temp gauge(questionable), tested the oil probe, checked the vernatherm(the seated position was in question by the shop) checked the vernatherm and it opened per the specs, flushed the oil cooler. I was finally able to test fly it after the CA fire Smoke cleared for a day or two, no luck still hot.
 

So I had the JPI 730 oil T prob installed for a check as a backup and sanity check to the analog gauge. I test flew it again. 
 

Settings: climb out (120 mph) to 6,500 MSL it got up to 215*. Short Cruise 5-10mins: 2400 rpm 21” MP Oil Temp hovered around 199-205  on the JPI. OAT approximately 75 degrees F

 

today I flew for my Flight Review and some final transition training. We were at 6,500 msl for an hour. While at alt the power settings where at 2400/24” - temps soared to 231*, OAT 67 degrees F. I pulled back to 21” MP opened the colw flaps and left the CHT’s alone as they where at 1375, thereabouts - Oil Temps came back to about 210* 

Any thoughts on next steps? I looked into the oil cooler relocation STC from LASAR but it states Non-dog house baffles and 1967 and newer so, that’s out. 

I read this thread in full and tried almost all

 

thanks for your time and help! 
 

Vince 

 

 

 

 

 

All I just want to say thank you for your help, questions & suggestions. I will work to gather this information and get it back to you all over the next week. 

 

I will go up and log the information. I also can try to sort out how to log the information from the EM JPI 730 and share my settings. 

 

 

 

 

 

 

[Jvharps]

11 hours ago, Ragsf15e said:

I’m not gonna have a solution for you, but a few questions that might help us... how are the CHTs at cruise?  How are you leaning?  Rich of peak lean of peak, peak?  And how much rop or lop?  Do you have the metal “heat shield” on top of the lines to the oil cooler?  What about the one behind the oil cooler?  Are the mags timed correctly, recently checked?  I can see my oil temp go up some as my Surefly advances and my CHTs go up a bit.  **raw egt numbers aren’t going to help us much, but CHTs might, what temps are they in climb and cruise?  Are they relatively even, are the egts relatively even?

Just FYI, the OATs you stated are pretty warm at altitude.  190s in cruise oil temp wouldn’t be a surprise.  The higher oil temps in climb or maybe doing maneuvers on your flight review can happen if you’re not rich enough and slow down (like for slow flight).  You will see the CHTs rise and then the oil temp is pretty quickly behind them.  

Hi Ragsf15e, 

 

Thanks for your suggestions and inquiries. See Below for the current best responses:

 

how are the CHTs at cruise?  I will pull the JPI data and provide this 

How are you leaning?  Rich of peak lean of peak, peak?  ROP, I am leaning to 1350 EGT's 

And how much rop or lop? I haven't spent enough time in flight yet to log this but, your giving me reasons! ;-)

 Do you have the metal “heat shield” on top of the lines to the oil cooler?  Yes, please see the picture and tell me what you think. If you have an E model, is yours similar?

What about the one behind the oil cooler?  See picture. Its open. 

Are the mags timed correctly, recently checked? I am not sure how to know this, at run up, I get an even mag drop on the RPM's of ~50 RPM's

 I can see my oil temp go up some as my Surefly advances and my CHTs go up a bit.  **raw egt numbers aren’t going to help us much, but CHTs might, what temps are they in climb and cruise?  I'll note when I pull the data.

Are they relatively even, are the egts relatively even? Relatively. The delta is about 35-40 degrees if memory serves. 

[Jvharps]

11 hours ago, takair said:

Which model Mooney do you have?  As Rags suggested, what are the CHTs running at, you said normal, but are they below 380?  Old Mooneys are very finicky about cooling.  You want ALL of the air going through either the cylinders or the oil cooler. If air is going past those through leaks, cracks, etc. It is stealing from the ability to cool the heads and the oil.  While the cowl opening is huge, airflow is limited by the cowl flap opening.  If air is bypassing the things that need cooling, it is the path of least resistance out the cowl flap and limited air through the oil cooler.  Have your mechanic look really close at all opportunities for air to escape these areas.  It can be time consuming, but worthwhile.  Other things to look at are mag timing, but CHT is usually a give away there.

Will do this! I also, will work on the YouTube video posted to look for these air-leaks using a bright light under the dog house and see where light emits.

 

I will grab the JPI EM data and share. Or at least log in flight. 

[Jvharps]

11 hours ago, N201MKTurbo said:

You might want to inspect the vernatherm seat. I resurfaced mine once and it did improve the oil temps, not an earth shattering change but maybe 5 deg better.

Yes! I forgot to add this to the Original post. The seat was resurfaced, and installed. This was before the JPI Oil T prob was installed so Im not sure of the benefit. However, the position was reported to not have been seated correctly before this was done. 

[Jvharps]

11 hours ago, carusoam said:

Welcome aboard jvh.

How technical are you? - Fairly, not a mechanic but I do have a strong interest to understand the operations. I have restored a classic truck and maintain my own vehicles so, generally mechanical. Not so much in the Aviation sense but, learning. 

You have been doing some reading... LOL, my wife says the same!

Lets see if you missed anything... I'm sure I have, leaning on the groups experience and frankly, grateful!
 

1) Oil absorbs much of the heat generated by the engine... ..Copy that.

2) It dumps this heat using the oil cooler...Copy that.

3) The vernatherm starts off closed open, and opens closes, as the oil warms up... as it opens, it sends oil to the oil cooler...  (See Rich below for the correction) ..Copy that.

4) Oil coolers stop working after a while.....Recently Overhauled by Pacific Oil Cooler Services. I had it flushed again on the field to scratch it off the list. Of course, if there is a blockage, its blocked. 

• They get dirty on the outside - its pretty clean. 
• They get dirty on the inside - Flushed it, but as you stated could be clogged.
• They get their fins crushed by unknowing owners - fins are in great shape. 
• They get mis-plumbed as we have seen around here lately - Can you take a look at the photos provided and note if you see something amiss? 

5) To know how well your oil cooler is working (Not working) it doesn’t take much more than an IR thermometer from HF.... Tested this prior to the JPI probe. The IR showed that the Oil cooler was about 30-40 degrees cooler. I havent dont this again sense I picked the plane up from the shop. I'll pull the cover and check this again after my next flight. 

What should the difference's be between the Oil cooler and say the oil pan(automotive talk, sorry)

 

 

11 hours ago, carusoam said:

6) If you are Seriously concerned about the oil flow through the oil cooler... there is a simple method to check all the hoses and wash things out... What is this simple method?

7) It simply could have a lot of sludge in the bottom of everything...  I agree. At motor shut down, I do hear oil "gurgles" from the front of the motor. I figured this is just from the prop!? Is there any additive to run through the oil to clear this throughout the system? 

I did change the oil from 50wt.  Aeroshell 100w Plus when I got home. 

8) Instrument accuracy... make sure the oil temp gauge is telling the truth... My thoughts exactly, so I added the Oil T prob to the JPI for a cross check. 

9) 205°F in Cruise sounds pretty normal to me... I would be happy with this. My perception is, that at 6,500 msl, I should be able to run the motor at say 2400 RPM / 24" and close the cowls and maintain this temp but, yesterday at this configuration thats when the Oil T's went up to 230 degrees. I was forced to pull it back - so down - open flaps = oil temps came down to 213 degrees. 

10) The needle should always be within the green arc after T/O...  ..Copy that.

11) verify you have the right part number on your vernatherm... It is easy for the unknowing to replace it improperly...I will take a picture and post that. 

12) very often dog houses leak precious cooling air... baffle seals can be equally leaky... ..Copy that. I will use a light and look for air leaks. 

First thing you want to do... Is add some detail about you and your plane... it is called the avatar area... if you are using a small screen it will be more challenging to do... ..Completed. Good call!

It is hard to solve problems when we don’t even know what plane you are flying... or where you are flying it... (the title is a good place temporarily, realistically, who’s memory is that strong by the time you have gone down the page... ..Copy that.

It is kind of odd you haven’t mentioned what your transition trainer has said about the challenge... Expect that he knows a bit more about this plane than you... ..I did review with him my steps, he is pretty mechanical but is a CFII. We referenced the POH tables and tested a couple of settings. described above. 

PICs are the next best thing... if you don’t have an engine monitor supplying data use your cellphone... capture some pics...  ..I will grab the JPI data and post or at least log this. 

Best regards,  - Thank you for your help!-a-

 

 

[Jvharps]

11 hours ago, MikeOH said:

My '70 F oil temp runs hotter than I'd like, but better since I redid the baffles (I had high CHTs, as well.  Ran into the low 400s before I fixed the baffles).  CHTs run 320-350 now, even on hot days.  I do run LOP.

OIl temp is still around 215-220 in cruise, and can get to 230 in climb on a hot day.  I've had the oil cooler overhauled by Pacific OIl Coolers (not just flushed), replaced the oil lines to/from the cooler, checked the vernatherm and its seat...

I've just learned to live with it.  The factory gauge never gets past the green, but it teeters on the edge sometimes!

I am prepared for this result but, I would like to make sure there is not something that is holding this temp up and/or keeping the plane in good shape. I do appreciate your sharing your experience with it. 

[takair]

Do you have a large hole in the air filter plenum box, just below and left of the alternate air door?  Likely unrelated to the issue, but....   Regarding leaning...Leaning to a specific EGT can put you anywhere and that could be good or bad.  Try leaning to 100ROP to get a baseline.  This is generally a safe starting point to baseline your temperatures.  Regarding the mags, find out the basic mag timing. 20 or 25 degrees.  25 runs warmer.  You mechanic should check that both mags match during annual.  Good mag drop likely means they are set adequately, but 25 will still be warmer.  Getting the CHT values will be a great help to troubleshooting further.  Lots of excuses to be around your new airplane.

[David Lloyd]

A couple general observations:  I had a GAMI injected IO550 Bonanza.  During the first thousand hours or so, I fiddled quite a bit with the mixture, recording what happened.  Between 40 and 50 degrees ROP at any throttle setting, resulted in the highest CHTs.  Couldn't do anything with the mixture to make it hotter.  Richer, the CHTs went down.  Leaner, the CHTs went down.  Altitude, OAT, throttle setting, EGT's would be all over the place but the result is the same.  What the pilot guide directed to set the mixture would result in the hottest result.  Go figure.  Later, with the RV, oil temps were a concern.  I saw a direct correlation between cylinder head temps and oil temp. When I ran ROP, the cylinders would be near 400 degrees and the oil temp in cruise would be 205 to 215 depending on the air temp.  Pull the mixture back, run LOP and the CHTs would come back down to the 360-370 range and the oil temp would drop to about 195.

So, anytime someone talks about CHTs or oil temp being high, the first questions should be is what are all the temperatures and are you ROP or LOP

[DXB]

1 hour ago, Jvharps said:

 

 

The relevant territory regarding oil temps seems to have already been covered here.

So I'll go off topic and mention that you might want to consder some fire sleeves for your oil and fuel hoses 

[Ragsf15e]

10 hours ago, Jvharps said:

All I just want to say thank you for your help, questions & suggestions. I will work to gather this information and get it back to you all over the next week. 

 

I will go up and log the information. I also can try to sort out how to log the information from the EM JPI 730 and share my settings. 

 

 

 

 

 

 

@takairsaid this but I’m gonna go out on a limb and say it more clearly... leaning to a specific egt in cruise is wrong.  There is a “target egt” method for climb but that’s different.

Even if you’re flying at the same altitude as yesterday when you leaned properly, there are other factors like temp and pressure that might affect your egt.

Step one for your troubleshooting is going to be to set up for cruise at say 7,500’, 2500rpm, full throttle, close to full rich.  Then slowly lean, very slowly.  Watch the egts rise.  They will go up until they peak, then they will drop again just like @N201MKTurbosaid.  They may not peak at exactly the same time.  That’s ok.  You just need the first one.  Once the first one peaks, go RICH until that egt drops 100 degrees.  Boom, done.  You are 100rop.  Now let it settle and see where your chts and oil temp are.  Next time we’ll do lop.  In either of them, you can be off by say 25-50 degrees of egt and it will make a huge difference.  Go slowly and get it pretty close.  If you were to say set 50 rich of peak, you’ll definitely have hot chts and oil!

Your pictures look good.  Nothing really obvious.

[carusoam]

Your JPI is a magical device...

It can tell you something about the difference in timing of your two mags...

Often, an OH’d Mag’s timing will drift a bit during its first hours of operation... a recheck is done on a schedule...

If one has drifted... it will make itself known during the run-up...

Use care when you do an instrumented run-up... allow about 15 seconds of time on each key position to collect enough data to report properly... This is when your data rate is set to two seconds... it takes time for the EGTs to stabilize...

The graphs reported by Savvy should show two identical humps... often they aren’t identical... if one hump is taller than the other... this is a timing issue... 

Note: you have plenty of technical experience for this stuff... 

As far as flushing out the oil system... check in with a mechanic for that... you don’t want to accidentally leave a lot of solvent in the oil cooler or lines... it will show up in the wrong place if it were to occur...

 

PP thoughts only, not a mechanic...
 

Best regards,

-a-

[MB65E]

I noticed you are missing the air deflector installed on the aft side of the cooler. That helps keep air flowing through the cooler and down out the exits instead of back flowing by the cylinders. Also, check to make sure the correct gasket is on the oil pressure screen housing for which housing you are running. There are three different setups. Stock oil pressure screen housing, remote housing, and oil filter housing. I once installed the oil filter housing and I used the pressure screen gasket. That didn’t work too well. The IPC isn’t very good. I may have missed it but has The vernotherm been inspected? I see you have a fresh pacific oil cooler sticker on the cooler. They’ll test the vernotherm as well! 
Finally, I’ve sealed the front areas with silicone around gaps by the cooler and the cowl. Some have made air dams to trap the ram air into the cooler. Not advising, but I’ve seen it on several M20’s at OSH. 
-Matt

[takair]

4 hours ago, MB65E said:

I noticed you are missing the air deflector installed on the aft side of the cooler. That helps keep air flowing through the cooler and down out the exits instead of back flowing by the cylinders. Also, check to make sure the correct gasket is on the oil pressure screen housing for which housing you are running. There are three different setups. Stock oil pressure screen housing, remote housing, and oil filter housing. I once installed the oil filter housing and I used the pressure screen gasket. That didn’t work too well. The IPC isn’t very good. I may have missed it but has The vernotherm been inspected? I see you have a fresh pacific oil cooler sticker on the cooler. They’ll test the vernotherm as well! 
Finally, I’ve sealed the front areas with silicone around gaps by the cooler and the cowl. Some have made air dams to trap the ram air into the cooler. Not advising, but I’ve seen it on several M20’s at OSH. 
-Matt

Matt. Interesting regarding the oil cooler plate. I had looked into that at one time and was convinced it was only for C models and not the E. Do you have one on your E?

[Guest]

19 hours ago, Jvharps said:

I am prepared for this result but, I would like to make sure there is not something that is holding this temp up and/or keeping the plane in good shape. I do appreciate your sharing your experience with it. 

To save yourself money buying expensive parts which are at times hard to get, don’t let you lower cowl hang from the air inlet coupling.

Clarence

[Bart Chilcott]

I have a 65E with the oil cooler relocated aft in the cowl and the cowl closure mod.  The highest I have ever seen my oil temp on my JPI was 230.  That was on a super hot day during climb out.  Normally, my oil temp is Between 189 and 192 degrees at cruise and it’s VERY consistent.  My CHT’s range from 340 to 370 during all phases of flight.  I run ROP.  You’ve received some great technical advice here.  A couple things that separate our E’s from our J brothers who share the same IO360 is, the E model doesn’t have very large cowl flaps.  Unlike its J and later brethren who have larger, barn door cowl flaps that extend down much further than the E.  Make sure you’re leaving those cowl flaps open on climb out and honestly, as small as they are on the E, I leave mine open during short low level flights and they are part of my landing checklist and opened up just after gear extension.  Our planes engines are tightly packed in their cowlings making cooling a challenge.  When it’s hot out and your climbing out, adjust your climb angle.  For me, 120 indicated works perfectly.  But if I decrease speed, increase pitch, I’ll see temps go up rapidly. 

[MB65E]

4 hours ago, takair said:

Matt. Interesting regarding the oil cooler plate. I had looked into that at one time and was convinced it was only for C models and not the E. Do you have one on your E?

I installed one on my E. Again the IPC is not very good. I think it helps, but no data. The physics make sense.
attached is a highlighted picture of the IPC where it lists a “plate” for the E/F. 
-Matt

 

[takair]

2 hours ago, MB65E said:

I installed one on my E. Again the IPC is not very good. I think it helps, but no data. The physics make sense.
attached is a highlighted picture of the IPC where it lists a “plate” for the E/F. 
-Matt

 

It seemed to be originally installed on the C via service bulletin to prevent cracking of the adjacent exhaust pipe due to “cold” air being blown on it.  In the E, the pipe is further.  I have wondered if it would also work in the way you suggest.  Did you note any improvement with it?

[Old Chub]

This may not apply to the OP situation but it happened to me.   I started seeing high oil temps out of the normal range and near red line on a return flight.  After some troubleshooting it was found that there was a set of knife disconnects about 4 inched from the temp bulb connector along the firewall.   The knife connectors were showing signs of corrosion and building up or providing additional resistance to the circuit.  This additional resistance was making the indication on the instrument panel gauge show high.  Fix: New wiring installed from Temp Bulb disconnect on engine to gauge in instrument panel. 

1968 M20C