Even higher oil temp after new Vernatherm valve

[AaronJr]

I have a question regarding my oil temperature.

Since my oil temp had been running high (around 200-205°F), I recently replaced my Vernatherm a few days ago. However, during my first flight after the replacement, the oil temperature climbed to 225°F and was still rising, so I immediately returned to the airport.

I wanted to ask what could cause a new Vernatherm to result in even higher oil temperatures.

I also compared the new and old Vernatherm valves at the same temperature, and I noticed that the new one expands significantly more than the old one.

I would appreciate your insights. Thanks!

 

1968 Mooney m20f, 201 cowl, overhauled oil cooler

[N201MKTurbo]

It is possible your Vernatherm seat needs to be cleaned up. The old one could have warn into the warn seat.

I did mine once on my old M20F and it improved the oil temp. I knew the owner of the local engine shop and he loaned me the tool. It took about two minutes to do it after the Vernatherm was out. Like most Lycoming tools, If you go to buy one, it will cost like $5000.

https://www.lycoming.com/sites/default/files/attachments/SI1316A%20Bypass%20Valve%20Seat%2C%20Oil%20Cooler%2C%20Repair%20of.pdf

https://www.aircraftspruce.com/catalog/eppages/lycomingtools_07-17473.php
 

[AaronJr]

8 minutes ago, N201MKTurbo said:

It is possible your Vernatherm seat needs to be cleaned up. The old one could have warn into the warn seat.

I did mine once on my old M20F and it improved the oil temp. I knew the owner of the local engine shop and he loaned me the tool. It took about two minutes to do it after the Vernatherm was out. Like most Lycoming tools, If you go to buy one, it will cost like $5000.

https://www.lycoming.com/sites/default/files/attachments/SI1316A%20Bypass%20Valve%20Seat%2C%20Oil%20Cooler%2C%20Repair%20of.pdf

 

 

[N201MKTurbo]

Most I see look way worse than that one.

[AaronJr]

5 minutes ago, N201MKTurbo said:

Most I see look way worse than that one.

my ap says seating looks good, so i dont know what could go wrong

 

[Utah20Gflyer]

The new vernatherm could be defective.  You could remove it and test it to verify it opens at the right temperature.  I believe there also might be two different versions that open at different temperatures, you might check which one was installed, neither should run at 225 degrees though.  

[N201MKTurbo]

You could use an IR thermometer or thermocouple to see if your oil cooler is getting hot. If you have access to an IR camera, you can see if all the channels are working.

[MikeOH]

2 hours ago, N201MKTurbo said:

You could use an IR thermometer or thermocouple to see if your oil cooler is getting hot. If you have access to an IR camera, you can see if all the channels are working.

In my now over 7 year saga to determine why my oil temp is high, like the OP, I tried this.  By the time I taxi back to my hangar and have someone point an IR thermometer at my oil cooler the oil temps have already dropped.

I also tried to instrument the oil cooler inlet and outlet fittings with thermocouples but the temps were too low to be believable unless there is no flow through the cooler...but, I had the oil cooler overhauled and new lines installed, along with a new vernatherm!

Looking at engine monitor data the vernatherm opens and oil temp stabilizes at 180 degrees after 5-10 minutes at idle, so the vernatherm must be opening.  Once I go to take-off power the temp climbs to as much as 230 during climb on a hot day, then decreases and stabilizes at around 200-220 depending upon OAT and power setting once in cruise.

Now that I've overhauled cylinder #2 oil consumption has gone down to 7-8 hours/quart, so I don't think it's blow-by.  Very frustrating, but I just continue to live with it

[N201MKTurbo]

After all my recent magneto weirdness, now my engine is running relatively cool. I cannot explained it. But this weekend I flew to Bullhead City and my CHTs were running under 350 in cruise with fairly high fuel flows LOP. Anyway, my oil temp was about 220 in climb and 195 in cruise.

[A64Pilot]

A vernatherm of course works by expanding when hot and closing off the cooler bypass.

There is always some oil flow through the cooler.

I would bond a thermocouple to the tank part of the cooler and go fly and see what your temp is, it should be somewhat close to the indicated temp.

Have you verified your temp indicating system is accurate?

[MikeOH]

7 minutes ago, A64Pilot said:

A vernatherm of course works by expanding when hot and closing off the cooler bypass.

There is always some oil flow through the cooler.

I would bond a thermocouple to the tank part of the cooler and go fly and see what your temp is, it should be somewhat close to the indicated temp.

Have you verified your temp indicating system is accurate?

I will try that.

The only verification is that my thermocouple/thermometer reads ambient temp and agrees with my Insight G3 ambient temp readings before startup/flight.

[Brian2034]

Just a thought, how’s your engine timing? 
We had a engine running higher than normal oil temperatures after an annual and realized they had incorrectly set the timing a couple of degrees advanced.

[MikeOH]

12 minutes ago, Brian2034 said:

Just a thought, how’s your engine timing? 
We had an engine running higher than normal oil temperatures after an annual and realized they had incorrectly set the timing a couple of degrees advanced.

Hmm, a good suggestion.  In my case, I've had the high oil temp issue since I purchased the plane over 7 years ago and have had the mags overhauled since then.  Further, I had the left mag off when replacing the oil filter adaptor gasket (can't get to the mounting nut with the mag installed, UGH!).  So, unless all of those removals/installs set the timing too far advanced...

[Brian2034]

7 years! 
I’m guessing your timing should be good but its easy to check.

Blocked oil cooler

Poor air flow through the cooler

Restriction in the oil lines 

[N201MKTurbo]

Are your oil cooler lines hooked up correctly? It should go in the bottom and out the top.

[N201MKTurbo]

 

[MikeOH]

2 hours ago, Brian2034 said:

7 years! 
I’m guessing your timing should be good but its easy to check.

Blocked oil cooler

Poor air flow through the cooler

Restriction in the oil lines 

BTDT

Oil cooler overhauled.

Oil cooler sealed around edges. New baffles.

New oil lines to/from cooler.

[MikeOH]

2 hours ago, N201MKTurbo said:

Are your oil cooler lines hooked up correctly? It should go in the bottom and out the top.

The cooler itself has BOTH fittings at the bottom of the cooler, so I don't think that's it.

There seems to be several ways to hook up the to/from oil cooler lines to the accessory case and I've always wondered if mine is hooked up right; several A&Ps have said it's okay.  But, I believe both hoses go to ports near the top of the case; I would have thought one would be towards the bottom.  BWTHDIK?

[MikeOH]

2 hours ago, N201MKTurbo said:

 

Thanks for that link!

Mine is hooked up like that OP's.  So, I guess it's okay (like my A&Ps have told me)

I do wonder, because I have an oil cooler with fittings at the bottom, If I have entrapped air in the cooler?? It appears to be a 'cross flow' design so I guess that could happen.  I'd just think, long term, the air would eventually work its way out.

[N201MKTurbo]

So, you have the original M20F oil cooler which is installed with the long axis vertical, but you moved it behind cylinder 4 like a 201. Now it has its long axis horizontal. You might benefit from changing to a 201 oil cooler which is designed to be mounted horizontally with both connections on the same side.

[MB65E]

There are 3 gasket types, two pressure screens and 2 different remote oil filter housings. I had the wrong gasket on mine. Blocking the oil cooler only when it was warm.
-Matt 

[MikeOH]

9 minutes ago, MB65E said:

There are 3 gasket types, two pressure screens and 2 different remote oil filter housings. I had the wrong gasket on mine. Blocking the oil cooler only when it was warm.
-Matt 

UGH!  I wonder if that could be it.  It sure fits the symptoms.

My oil filter is NOT remote but I did note there are two different oil filter adapters and I THOUGHT I was careful picking the correct gasket.  But I really only checked that the new gasket matched the OLD one when I was stopping an oil leak. Gawd that was a pain to R&R the adapter...

I think I'm going to try the thermocouple on the oil cooler tank to see if it is even getting hot.  If not, you may be onto the problem!

[MikeOH]

1 hour ago, N201MKTurbo said:

So, you have the original M20F oil cooler which is installed with the long axis vertical, but you moved it behind cylinder 4 like a 201. Now it has its long axis horizontal. You might benefit from changing to a 201 oil cooler which is designed to be mounted horizontally with both connections on the same side.

No, my cooler is in its original location, up front, vertically mounted with both inlet/outlet fittings at the bottom.

[N201MKTurbo]

17 minutes ago, MikeOH said:

No, my cooler is in its original location, up front, vertically mounted with both inlet/outlet fittings at the bottom.

I had you confused with 5he OP.

[AaronJr]

I'm going to drain some oil out of my system, my AP put too much in, and when cold it shows 8.2 on the stick, too much oil also caused reading not correct and flow not right,

so that will be my first fix