Stubborn Oil Leaks

[JonJay]

I have an small oil leak on my lower oil cooler fitting and another on my oil temp probe that I just can not seem to get stopped.
The fittings are tight. I have tried EZ turn fuel lube and Permatex thread sealant. Neither seemed to do the trick.

Any suggestions?

[dan]

Teflon tape may be the saving grace. Before you burn me at the stake, know that this is the practice used by Pacific Oil Coolers. Just don't get any tape inside, and you'll be fine.

[sglaeser]

Originally Posted by JonJay

I have an small oil leak on my lower oil cooler fitting and another on my oil temp probe that I just can not seem to get stopped.
The fittings are tight. I have tried EZ turn fuel lube and Permatex thread sealant. Neither seemed to do the trick.

Any suggestions?

If the oil cooler fitting is leaking on the flared connection side try a del seal. I had some small leaks through the flared connections and the seals fixed the problem (even though the flares looked flawless).

http://www.aircraftspruce.com/catalo...37fittings.php

If it isn't the flared connection side, then that's no help!

Right or wrong, when I installed the fittings into the oil cooler I went for an extra turn. The EZ lube helped achieve the extra turn. It felt like if I tightened it another 10 degrees I would snap off the fitting. That side didn't leak though!

[N908RV]

All the A&P's in my area use "Sealube":

http://www.aircraftspruce.com/catalo...es/sealube.php

Buy one can and it will last you for a lifetime. No offense to Dan on the teflon, but this is better. Teflon is great, but as Dan says you have to be careful with it. I only use teflon on instruments, etc.

The other item that you mentioned (EZ Turn Fuel Lube) is great stuff, but all the A&P's reserve that for gasket paste. It is AWESOME gasket paste. you can pull off the gaskets 5 years later and they are like new and the paste prevents leaks. I use it on almost all paper gaskets.

But Sealube is better for fittings than EZ Turn. I have NEVER had the tapered NPT fitting leak with this sealant.

If it is in fact your 37 degree flares that are causing the problem then the special seals that Steve mentioned are the way to go.

PS: I was a diehard Permatex user for years until I found this stuff. Permatex is great stuff, but you have to have the fittings absolutly clean with no oil residue to get the Permatex to work. Hard to do on an in service cooler. That may be part of your problem. Also Permatex is only midly less annoying to get on you than Proseal B-2. Requires strong language and chemicals to remove. Sealube comes right off with a towel.

[Mel]

Another trick I've used for more years than I care to remember on the flare fittings is: First make sure they are clean and have NO scratches, then apply a very small drop of blue lock-tite to the flare and install. Never had one leak after doing this. On the pipe threads, I still use Permatex "form-a-gasket".