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Leaky oil cooler fitting

iamtheari

Well Known Member
I'm 10 hours into my RV-14's Phase I, so it's time for the first oil change. While trying various methods to remove the Lycoming-over-torqued oil filter, I am also working on finding the source of the oil on my plane's belly. I have found oil seeping from what appears to be the lower/forward fitting on the oil cooler. Specifically it seems to be coming from where the 90-degree elbow is threaded into the oil cooler.

So, the question is this: Can I tighten that elbow 360 degrees where it sits, should I remove it first, or should I buy a new elbow altogether?
 
Cooler leak

Feel a little expert like since just replaced on my O320. Mine is baffle mounted behind #4. I’d remove if I wanted to change the angle of the 90 fitting, especially since lower hose/ 90. The aluminum is soft, you need two wrenches to rotate safely. Remove cooler and rotate...

If firewall mounted, you may be able to get two wrenches on it. It may be best to remove 90 and reapply pipe sealant , then tighten. If 90 is aluminum, steel is recommended to prevent future galling so I read.
 
Thanks for that. The RV-14 taildragger kit comes with an AN822-8D for that position, which is aluminum. The oil cooler mounts to the engine mount.

I guess I'll order a steel AN822-8 elbow and see if I can get two wrenches in there without pulling the cooler off the plane, but emotionally prepare myself for having to remove it completely.
 
If you do remove it, it might be worth your time to do a quick leak check of the cooler. I had a failure at about 80 hours that was not observable other than a little oil at one fitting. I removed it to check/ replace the fitting and instead found a leak in the cooler. :eek:
 

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If you do remove it, it might be worth your time to do a quick leak check of the cooler. I had a failure at about 80 hours that was not observable other than a little oil at one fitting. I removed it to check/ replace the fitting and instead found a leak in the cooler. :eek:

Agree - definitely leak check the cooler.

Last week, my 2006X oil cooler developed a nice crack after only 17hrs; we pressure-tested it and sure enough, the end of one of the 13 cooler segments had a nice crack (that, in flight, spewed about 1qt of oil in ~10min). It took us a while to determine the location, since we too originally thought it was the fitting. Fortunately, oil started leaking at the end of my flight rather than the beginning - I hate to think about what would have happened if I wasn't so fortunate.

I'm in the process of working with Airflow Systems to send it back to them for analysis - hopefully, they will send me an RMA soon. In the meantime, I purchased and installed a new oil cooler from Aircraft Spruce - Phase 1 has to continue!

_Alex
 
I also had a failure of my 2006X oil cooler at 60 hours. Happened on descent into Memphis on a 3 hour leg from West Texas. I noted the oil pressure fell from the usual 70's psi down to about 60. When I landed there was about 3 quarts of oil on the firewall and on the underside of the plane. I was able to get a new cooler overnighted and got back on my way. I took the opportunity to replace the elbows with steel at that time.

Sounds like there may have been a bad batch of oil coolers lately. I sent the bad cooler back to Airflow Systems for analysis.

Bottom line: Definitely leak check the cooler.
 
Forgive my novice question... What is the process for leak checking an oil cooler?

I just plugged one end and pressurized the cooler with air at something less than standard oil pressure (40 - 50 psi works). Use a soap solution or purchase a leak check solution from your local HVAC supply. My leak was inside the cooler, but as the photo shows, was easy to spot.
 
Leak test

I submerged my cooler in a clear tub of water up to the fittings. I borrowed a thumb of a passer by my hangar door, applied 15 lbs pressure from rubber end blow off nozzle ....bubbles appeared. Still cleaning up blown out oil after two post replacement flights. FYI... the first time testing no bubbles......my left hand hid them, never saw them, reinstalled....uggh ! My cooler lasted 29 years no issues.
 

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This is an interesting post, I had the same think happen to me with about 70 hours on my RV 9a O 320 last year on a flight down to Dayton OH . Oil cooler mounted behind number 4 cylinder. When I got out of plane discover oil covering bottom of plane lost 4 of 6 qts. Oil pressure never fluctuated. My guess is it occurred very close to destination. Thankfully. Upon pressure testing the cooler found a crack at the bottom of cool in the first row. Similar to previous post by Med. Not sure how or why that occurred, but I find it interesting that I am not the only one that has had this happen too. Scott RV9a N518SD
 
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