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Low oil temp


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Hello,

after a period of inactivity of 4 months, I find that I can not raise the temperature of the oil of my aircraft to more than 165. it is very low and I even received a warning from savvyanalysis because 96% of aircraft have a much higher temperature. 

 

Anyone has an Idea ?

 

thanks

cyrille

Edited by Dood
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Cyrille,

Talk to your mechanic... the vernatherm seems to be stuck open1, sending the oil to the oil cooler all the time...

the vernatherm is temp sensitive and gets tested by putting it in a pot of water.  Raising the temp, closes the valve...

 

if it doesn’t meet spec it gets replaced...

keep an eye open for anything stuck in the valve.... chunks of metal would be bad.... (unlikely)

PP thoughts only, not a mechanic...

Best regards,

-a-

 

note 1:  the vernatherm May be stuck allowing oil to flow to the cooler.   Whether it is stuck open or closed depends on what oil line it is in...?

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Hello,
after a period of inactivity of 4 months, I find that I can not raise the temperature of the oil of my aircraft to more than 165. it is very low and I even received a warning from savvyanalysis because 96% of aircraft have a much higher temperature. 
 
Anyone has an Idea ?
 
thanks
cyrille


It sounds like your Vernatherm is stuck open.


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A common misconception here but a vernatherm actually works backwards from a thermostat in a car. When it expands it plugs off the cooler bypass and forces the oil to go through the cooler. If it was stuck open you would have high temps. There shouldn't be a failure mode of the vernatherm that results in low temps.

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Thanks MB231... I added some edits to my post... :)

Check out my fancy edits above...

 

I’m not sure where the vernatherm is located on my plane...  in the cooler by-pass line, or the cooler’s oil line...

Either way... if it failed, it is allowing oil to the cooler when it shouldn’t... and can be tested in a pot of hot water...

If the vernatherm passes the test... it is probably a gauge issue after that... Compare OilT to the actual temp of the oil...measured independently.

PP thoughts,

-a-

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19 hours ago, carusoam said:

Thanks MB231... I added some edits to my post... :)

Check out my fancy edits above...

 

I’m not sure where the vernatherm is located on my plane...  in the cooler by-pass line, or the cooler’s oil line...

Either way... if it failed, it is allowing oil to the cooler when it shouldn’t... and can be tested in a pot of hot water...

If the vernatherm passes the test... it is probably a gauge issue after that... Compare OilT to the actual temp of the oil...measured independently.

PP thoughts,

-a-

On the IO-550-G the vernatherm is in the bottom of the cooler itself. Item 15 in the attached dwg. On the OP's aircraft, it depends on the engine but it is usually in the oil filter housing. No matter where it's located the function is the same. Oil is allowed to bypass the cooler core and as it warms up the vernatherm expands to block the bypass forcing oil through the core. It has a pressure relief spring on the end which allows oil to pass in the event of a plugged or congealed oil cooler so it doesn't explode! It is 1930's technology in a smaller package, pretty ingenious.

35_085.thumb.gif.ed69573154a70a5ad14dade53512c583.gif

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