Oil Cooler leak weirdness!

[Joe Larussa]

So I put in a brand new oil cooler because it had a leak and was almost as old as me. Then I noticed the six month old oil hose that goes to the bottom fitting was also leaking a little. Figured it must be the fitting. Swapped fittings and still leaking. Not a lot but still too much for my liking. It’s an aluminum fitting coming out of the cooler with stainless fitting on the hose end. Might that be the issue. Picture attached for your viewing pleasure.

[Joe Larussa]

Just now, Joe Larussa said:

So I put in a brand new oil cooler because it had a leak and was almost as old as me. Then I noticed the six month old oil hose that goes to the bottom fitting was also leaking a little. Figured it must be the fitting. Swapped fittings and still leaking. Not a lot but still too much for my liking. It’s an aluminum fitting coming out of the cooler with stainless fitting on the hose end. Might that be the issue. Picture attached for your viewing pleasure.

 

[EricJ]

Looks clean to me.

[Joe Larussa]

5 minutes ago, EricJ said:

Looks clean to me.

It’s pretty fresh oil.

[47U]

2 hours ago, Joe Larussa said:

Figured it must be the fitting.

I suspect you’ve already done these things so my apologies in advance…

You’re sure it’s the hose flare to the  elbow fitting and not the elbow fitting pipe thread to oil cooler that’s leaking?  Otherwise, a close inspection of the flare, perhaps with a magnifying glass, should be done.  And proper torque (270-350 lb inches for a -08).  Over torque can warp the fitting and induce a leak.  And over torque of the pipe thread can crack the oil cooler case, too.

Good luck.

[Joe Larussa]

7 hours ago, 47U said:

I suspect you’ve already done these things so my apologies in advance…

You’re sure it’s the hose flare to the  elbow fitting and not the elbow fitting pipe thread to oil cooler that’s leaking?  Otherwise, a close inspection of the flare, perhaps with a magnifying glass, should be done.  And proper torque (270-350 lb inches for a -08).  Over torque can warp the fitting and induce a leak.  And over torque of the pipe thread can crack the oil cooler case, too.

Good luck.

Thanks for taking time to reply. Yep I’m sure it’s leaking from the back side of the nut. I tried two different elbows coming out of the cooler with same results. Not sure on the torque. Can’t get a torque wrench on it. Hose is 6 months old so hard to imagine that’s the problem, but who knows.

[Andy95W]

If it’s coming from the back side of the nut, it sounds like the mating surface of the hose fitting isn’t making good contact with the flared elbow at the oil cooler.  It might be prudent to remove the hose and inspect that surface for abnormalities. 

Also, these are available as well:

https://www.aircraftspruce.com/catalog/hapages/del37fittings.php

[Joe Larussa]

3 hours ago, Andy95W said:

If it’s coming from the back side of the nut, it sounds like the mating surface of the hose fitting isn’t making good contact with the flared elbow at the oil cooler.  It might be prudent to remove the hose and inspect that surface for abnormalities. 

Also, these are available as well:

https://www.aircraftspruce.com/catalog/hapages/del37fittings.php

Thanks for the tip! Never heard of one of those. Will give it a try.

[PT20J]

Probably a long shot, but AN fittings have a 37 deg flare angle and some automotive fittings are 45 degrees. Might be worth checking that 90 deg fitting. 

[Ragsf15e]

If there’s a pipe thread (npt) fitting coming out of the cooler, are you sure there’s appropriate thread seal in there? Not required on the flared fittings, but it is on the npt fittings…

[Ragsf15e]

Also, @M20Doc may have to help us interpret this, but I think this lyc chart details the torque.  Disregard my red circle as that’s for something else.  I think you’re in the “flexible connection”section?

[carusoam]

That looks like all new hose fittings and elbows…. (?)

covered in a nice fire sleeve….

if the cone shaped oil fittings have the right matching angles… it should compress properly to seal…. Based on torque…  (in the automotive world, they might use a rotation description after finger tight)

If it is a used fitting… you might find that it has a scar from the first time it was tightened in place… the old scar makes a great leak opportunity… same for any scratches it may have got from being on a shelf and mis-handled in its prior lifetime…

Adding the nice extra aluminum seal could work… in a bandaid kind of way…

 

But….. where exactly is it leaking?

It looks like the nut wasn’t torqued enough to hold the elbow sealed in place… so the oil is escaping from under the nut… and running down towards the fire sleeve…

It might be wise to take the nut off and have a good look at those sealing surfaces…

Make sure you know where it is really leaking from… 

Mooneys aren’t supposed to leak any oil… except out the case vent when over filled….

So… you have a good reference to start with….

Fresh golden oil color… my favorite color! 

PP thoughts only, not a mechanic…

Best regards,

-a-

 

[Guest]

To me it looks like it’s leaking between the “B” nut and the fitting in the oil cooler.

From the J maintenance manual torques for tube fittings.

Clarence.

 

 

[Joe Larussa]

So I added the Del fitting. Ran it up and started to leak again after hitting 180 degrees of course. My mechanic watched as I ran it up. I brought it back to idle then he tightened it up just a hair more. Leak stopped. Ran it up again and so far dry. Yesterday I couldn’t even spell Del and now I own one! We shall see if it holds. Fingers crossed!