High Oil Temperature in Cruise

[Heybluez]

My typical cruise temps were between 195-205 but Friday I flew to Memphis from Charlottesville (~4 hours) and my temps were in the 225 range.  I opened the cowl flaps and kept the temps to 185 range.  I am flying back today and will keep an eye on temps but curious as to any ideas as to what I should check given the change?  

 

 

[ArtVandelay]

You probably want to post your model and a picture of your engine (cowling removed) so they can see your baffling.

[carusoam]

hey hey bluez,
 

Got any JPI data to post?

Got any OAT details to share?
 

Have you read any of the posts regarding the thermistor?

How it works, how to test it, how to change it out?

Might start simply with an inspection of the oil cooler, front and back... see if a bird built a home in there...

PP thoughts about OilT, not a mechanic...

Best regards,

-a-

[Heybluez]

 Went and took a look... looks like no bird nest but the baffle might need to be replaced.  Will do when I get back. I went ahead and pushed the baffle back as much as possible. Will see what she does tomorrow morning on way home.

btw. It’s a Mooney M20J.  Pic of baffle here.

 

 

[Guest]

  On 9/13/2020 at 8:57 PM, Heybluez said:

 Went and took a look... looks like no bird nest but the baffle might need to be replaced.  Will do when I get back. I went ahead and pushed the baffle back as much as possible. Will see what she does tomorrow morning on way home.

btw. It’s a Mooney M20J.  Pic of baffle here.

 

 

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The first step is to verify the accuracy of the gauge.  Faulty gauge, faulty vernatherm oil valve and quality of the baffle sealing.

Your left side baffle sealing tapes are folded backwards and the one across the back don’t look too healthy.  Time to track down Guy at www.csob.com and get some new tapes.
 

Clarence

[carusoam]

I Couldn’t get doc’s link to work...

So...

https://www.csobeech.com/GeeBee.html

This one gets you direct to @GEE-BEE’s store of awesome baffle seal materials... the most valuable part is probably the email address...

If the baffle seals flop backwards without telling you... it usually shows up in CHTs in a more obvious way than oilT...

But, they are both related... the necessary airflow is going somewhere else...

PP thoughts only, not a mechanic...

Best regards,

-a-

[carusoam]

Thanks for stopping in, GB!

looks like the seal matches the paint on this one...

Seeing if @Heybluez is still hanging around today...

Best regards,

-a-

[Heybluez]

Those look great!  

[Heybluez]

I asked a mechanic on my home base to check out my plane and he told me that my oil cooler doesn't have a vernatherm? I have a 1986 M20J. I'm confused, could be possible?  He wants to change the 'temp bulb' to see if that fixes it.  Thoughts?  Thx! 

[jetdriven]

The Vernathetm threads into the case on the Moonsy IO360 series.  You can remove it and throw it in a pot of boiling water to see if it expands thevquarter-inch required, it must expand to force oil through the cooler. Also, There is  a way to check the sealing  of the end of the Vernatherm  to the seat inside the accessory case, lycoming rents a tool to resurface that if you need it 

@cnoe is more versed on that 

[carusoam]

  On 9/24/2020 at 2:47 AM, Heybluez said:

I asked a mechanic on my home base to check out my plane and he told me that my oil cooler doesn't have a vernatherm? I have a 1986 M20J. I'm confused, could be possible?  He wants to change the 'temp bulb' to see if that fixes it.  Thoughts?  Thx! 

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Hmmmm...

That would be like a car that doesn’t have a thermostat...

Sure the mechanic doesn’t know where it is.... but he has got to know that one is required to maintain temperature...

What kind of mechanic did you did you go to?

PS there is a name for the temp bulb too... maybe he is not familiar with the lingo... Thermistor... a temperature sensitive resistor... 
 

This isn’t Mooney Magic... or secret codes... it is 1930s technology at its finest...  

You may have run into a mechanic that is really good at rebuilding engines and planes... but won’t go near electronic devices....
 

PP thoughts only, not a mechanic...

Best regards,

-a-

[Heybluez]

ha... out of curiosity -- where is the vernatherm?  I will go look for it tomorrow....

[jetdriven]

On the right side of the accessory case, it’s about a 7/8 inch hex that’ threads intro the case. 

[carusoam]

Find the oil cooler...

find the oil line into the oil cooler...

Find where there is a valve, often part of the oil cooler, that by-passes the oil cooler...

That would be the location...

For what it looks like... search for vernatherm around here... a few people have changed theirs out... they only last several decades...it is a brand name.... like Xerox.

There are pics posted around here... it is big enough to find easily, but doesn’t look like anything obvious...

Best regards,

-a-

[bfreelove]

FWIW Lycomings can be run without a vernatherm and just a simple pressure relief valve (not sure if that's what his A&P meant).  The relief valve was the original configuration however you don't see them much anymore.  Switching back to the relief valve is used sometimes in experimental setups as some people think it seals better than the vernatherm forcing more hot oil through the cooler, which lowers the oil temp.  I've used this technique before and it seems to lower the oil temps but will require much longer ground run to get to flying temperatures as the oil is always flowing through the oil cooler (only bypasses in case of oil cooler blockage).  Wouldn't be ideal in cold weather for sure. 

https://www.lycoming.com/sites/default/files/SI1008C Bypass Valve Installation.pdf

[Guest]

  On 9/24/2020 at 3:07 AM, Heybluez said:

ha... out of curiosity -- where is the vernatherm?  I will go look for it tomorrow....

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This might help you find it.

[Heybluez]

thanks all!

Funny, I guess we taught this mechanic something new.  Fun fact, I don't usually use the home field folks -- just did not want to fly my plan 30 minutes, get a ride back and all that so figured I would give them a shot.  Let's see.  Will report back.

 

[Heybluez]

Awesome.. we "found" it . Also a picture of the inner seat.

Looks ok BUT i dont know... haha.  Gonna try to heat it up in water and see what happens.  

 

 

[carusoam]

That’s it!
 

Great pics of both ends...
 

Adjusting gravity to keep it from falling off...

 

Modern manufacturing techniques could probably shave a pound or two off the weight of this here thermostat...

-a-