Veetail88

Well Known Member
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?
 
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.
 
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
 
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.
 
Your oil cooler

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.
 
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Think I'll change them.

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!
 
oil cooler

Veetail88,

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

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.
 
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:

100_2728a.JPG


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

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:

100_2728a.JPG


Thanks, Bob K.
 
Guilty

I did the same thing. Used aluminum fittings and didn't use a wrench to hold the cooler side of the fitting. I did use fuel lube so that might help.

I haven't started the engine yet. I'm inclined to leave it alone and check for leaks after I run it. Unless folks think this is a safety problem, I'm inclined to leave it alone.
 
Fuel lube won't seal the treads, you might as well bite the bullet and redo it now.
 
My neighbor has a Citabria that has been flying with its factory installed aluminum oil cooler fittings for 40 years with no issues. On that note, my 60 year old Tri Pacer sports aluminum fuel lines/fittings and copper primer lines ahead of the firewall - all without an inch of firesleeve to be found.

Adoption of a new "standard practice" does not make the old ways "bad".
 
I had an aluminum -6D fitting fail on the accessory case of my LongEZ after 1,300+ hours and replaced all 4 fittings (2 cooler; 2 accessory housing) with stainless steel -8 fittings and -8 teflon hoses. Pacific Oil Cooler Service removed the seemingly seized aluminum -6D fittings for me when they flushed/tested the cooler and recommended Bakerseal when installing the new SS -8 fittings. Oil temps dropped ~15*F when going to the -8 set up.

I now have only steel or stainless AN fittings and SS DOM solid plumbing lines aft (fwd ?) of the firewall after that unpleasant discovery.

dk
 
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Adoption of a new "standard practice" does not make the old ways "bad".

Perhaps thats true, however, the reason "standard practice" is continually changing is because we have learned there are better ways to do things that improve reliability and safety.

We don't build our cars, airplanes and a zillion other things like we did 40 years ago because we know a little more now, and chances are this road was paved with someone blood.

Why would you want to build a modern airplane using 40 year old methods? (bet you won't be doing this for your avionics!)
 
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Completely agree Walt, I'm no Luddite!

Steel fittings are "better" than aluminum, but not in the same sense that 4 wheel anti lock disc brakes are better than the undersized drums of 40 year old cars. Some improvements are marginal and some are huge. I'd say the move toward steel fittings and firesleeve has more to do with a few well placed lawsuits than any "major" safety improvement. After all, major safety issues kind of weed themselves out pretty quickly.
 
Walt

My fear is that I'll do more damage removing the aluminum elbow, than in just leaving it as is.
 
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.

1) if it hasn't galled already it's probably OK. If it has, taking the fittings out will likely ruin the cooler. Your choice, but for this issue I would pressure test and if it doesn't leak, I'd call it OK.

2) this is because joy can crack the cooler if you don't support it with a backup wrench. For this I would inspect closely and look for any sign of damage. If it is cracked, it will probably leak right away, but it may take several hours to develop. This is the issue that would be my biggest worry, but if it looks un damaged, it is likely good to go.

3) removing them will almost surely gall and screw up the cooler.

My opinion - test for leaks, look for damage, and decide based on that.

Tim
 
I read that article too

I read that article too and I definitely did #1 (with some thread lube) and probably did #2 and I cursed myself for my ineptitude.

I have 640 hours on it now so I think I am just going to let that sleeping dog lie. Just a data point folks.