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Oil Cooler Stopped Working

jahoosafat

Active Member
Hi Folks - After picking up my RV-10 post-painting (looks great! https://photos.app.goo.gl/VtwHQkkfMxy3afSz6 ), everything was functioning well except that the oil cooler seemed to have no effect on oil temps. Fortunately, the temps stayed in the green for the 3 hr flight, but I'm wondering what might have happened to the cooler and what diagnostics I might run. It's an Airflow Systems cooler (part #2006X). It could have coincidentally died while sitting for 4 months at the paint shop, but I'm dubious about that. I've got the cowling off and can't see anything obviously disconnected or damaged. I thought perhaps it was a breaker issue, but the cooler doesn't seem to have an independent breaker associated with it. Any ideas are appreciated!

Cheers,
Jeff
 
That's why I removed the cowling to have a look. Didn't see anything obvious like a leftover paint rag in there.
 
the oil cooler seemed to have no effect on oil temps. Fortunately, the temps stayed in the green for the 3 hr flight

Maybe you can help us and pinpoint where the problem is... green is green ;)
 
At 11k, temp was at 180 and I moved to close the cooler a bit to get it up to 185-195. Nothing happened to the temp, so I incrementally closed it fully and the temp didn't move. Toward the middle of the flight, I was at 19k and the temp was at 155. Changing the cooler from fully open to fully closed seemed to have no effect.
 
Is it the cooler? Or the cooler shutter?

Sounds to me like the cooler is doing its job wonderfully...
 
???

Are you talking about an oil cooler butterfly valve not working?

The oil cooler itself is passive; oil flows through it and back to the engine. There aid nothing electrical about the oil cooler itself.

That said, if there is an electric valve on the cooler inlet check that...

Check that there is nothing in the 4? SCAT tube running from the aft baffle to the oil cooler inlet. Make sure there is nothing in the SCAT.

The other thing to check would be the vernatherm which is basically a thermostat for oil temp. It has no electrical connections either; just temperature based. Not likely to fail, though...
 
At 11k, temp was at 180 and I moved to close the cooler a bit to get it up to 185-195. Nothing happened to the temp, so I incrementally closed it fully and the temp didn't move. Toward the middle of the flight, I was at 19k and the temp was at 155. Changing the cooler from fully open to fully closed seemed to have no effect.

Ok so the oil Cooler is working wonderfully, it sounds like you must have some sort of electric butterfly valve to choke off the airflow before the oil cooler that may not be working. Good news is that it's apparently stuck open so you're not grounded; wide open cooling is how most lycomings operate all the time.

I'm not familiar with any electric butterfly valve so maybe you could tell us a little bit more about your setup?
 
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t I'm dubious about that. I've got the cowling off and can't see anything obviously disconnected or damaged. I thought perhaps it was a breaker issue, but the cooler doesn't seem to have an independent breaker associated with it. Any ideas are appreciated!

Cheers,
Jeff

With the cowling off, did you turn the master on, run the valve from open to closed, and look and see if it actually moved?
 
I had the servo that controls the shutter fail. The servo tested fine so I’m guessing it’s a short in wiring. Mine failed close so my oil temps climbed. Your cooler is fine, check the servo and controller.
 
At 11k, temp was at 180 and I moved to close the cooler a bit to get it up to 185-195. Nothing happened to the temp, so I incrementally closed it fully and the temp didn't move. Toward the middle of the flight, I was at 19k and the temp was at 155. Changing the cooler from fully open to fully closed seemed to have no effect.

It?s not clear to me what your actions are intended to modify, *air flow* through the cooler (via a shutter) or *oil flow* through the cooler (via an oil control valve).

In either case however, your vernatherm isn?t designed to begin opening (to allow oil into the cooler) until oil temps exceed about 170F. If the Vernatherm is old, it may only open at higher temps or not at all. Even if it?s operating properly neither air or oil side ?controls? will have any effect as the vernatherm will be closed. If the vernatherm is stuck shut it will frustrate those controls at all oil temps.

Check it using the Lycoming service manual procedure.

Also, I am not aware of any particular concerns for oil temps at 155-180F at altitude. May need no action if your temps down low are ok.

Peter
 
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I had the servo that controls the shutter fail. The servo tested fine so I?m guessing it?s a short in wiring. Mine failed close so my oil temps climbed. Your cooler is fine, check the servo and controller.

My guess is that this is the correct hypothesis. But I'll let you all know what I figure out. Thanks for all the great diagnosis.
 
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