Oil Cooler Uh Oh....

Veetail88 · #1 06-03-2013, 05:01 PM

I received the last issue of Kitplanes magazine about 2 years too late.

There is an article in there about Oil Coolers.

They said DON'T do any of these things!

1. Don't use aluminum fittings, only steel as aluminum will gall the threads.
2. Don't tighten the fittings without holding back on the oil cooler wrench flats. Use 2 wrenches!
3. Don't take a fitting out once it's installed!

Apparently I did not do enough reading on this one before installation. I failed on #1 AND #2.

I've never added oil yet. Likely will in 3 or 4 weeks, but here's the question.

Do I fail on #3, take them out and replace them with steel?
Do I leave them alone and hope they don't leak and that I didn't jazz up the radiator already?

I hang my head in shame before the brain trust. What do ya'all think I should do with this?

airguy · #2 06-03-2013, 08:41 PM

It's never going to be as easy to fix it later as it is right now - and the absolute worst-case scenario today means you replace an oil cooler. A few years from now failure of the part means much more is at risk.

In your shoes, I would remove the aluminum fittings and inspect the threads carefully. Replace with a steel fitting if they are fine (you got lucky!) and replace the oil cooler if they are not.

erich weaver · #3 06-03-2013, 10:13 PM

My 2 cents: don't fix what isn't broken.

Just because there is a potential for galling doesn't mean there actually is, and I assume you haven't ripped the fitting off the oil cooler because you didn't use a backup wrench. Leave well enough alone. Sometimes I think more things get broken or fouled up by 'repairs' than through normal use.
My steel fitting to aluminum oil cooler connection had a small leak no matter what I did. Didn't have a steel replacement so used aluminum with a dab of an anti-galling goop and no problems since.
Erich

KRviator · #4 06-03-2013, 11:43 PM

If The Designer had wanted us to use steel fittings, He would have given them to us in the FWF kit...

To me, that says your aluminium fittings are good enough to leave in there.

scsmith · #5 06-04-2013, 03:08 AM

If your oil cooler is mounted to your baffles and hanging with the engine, then steel fittings are a very good idea. Even large-size aluminum fittings threaded into the engine can, and have failed.

If your oil cooler is mounted to the firewall, it seems pretty unlikely that those big-ol' 3/8" flare fittings are going to have any trouble lasting forever, even if they are aluminum. It is a very different environment there.

If you use pipe-thread compound on the threads like you should, not much chance the threads can gall with all that teflon shmoo in there. If you didn't use pipe-thread compound, then you should gamble and take them out, (I hope you can) assess the situation, and re-assemble with proper fittings and use the pipe-thread compound.

Veetail88 · #6 06-04-2013, 06:07 AM

My oil cooler is mounted to the baffle and I did use Teflon paste in assembly.

I don't believe I over torqued them so I'm hoping I didn't damage the cooler.

Steel fittings it is.

Thanks for the input folks!

DEWATSON · #7 06-04-2013, 08:27 AM

Veetail88,

Leave it alone. It will be fine. There's no telling how many experimental airplanes are flying with your setup with no problems.

rvbuilder2002 · #8 06-04-2013, 09:05 AM

I wonder what advice you would get from the thousands of RV (and Piper, Cessna, etc.) owners that have been flying for many years with aluminum fittings, if they posted.

I can't argue against the risk of galling (though proper assembly with a good thread sealant mostly mitigates it), but I would be very interested in seeing any accident report where failure of a -8 fitting was involved. I don't think there are any.

Bob Kuykendall · #9 06-04-2013, 06:35 PM

I can't speak to Kevin Eldredge's recommendation, but I'm pretty sure that his Nemesis NXT engine was reconfigured by the failure of an aluminum oil line fitting on the accessory case:

Thanks, Bob K.

scsmith · #10 06-04-2013, 06:53 PM

Yes, it was a number 8 aluminum fitting threaded into the accessory case. We saw it.

Quote:

Originally Posted by Bob Kuykendall

I can't speak to Kevin Eldredge's recommendation, but I'm pretty sure that his Nemesis NXT engine was reconfigured by the failure of an aluminum oil line fitting on the accessory case:

Thanks, Bob K.