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Scott Todd wrote:I've made observations on how much oil makes the belly a mess. 7 drops of oil (ok maybe not exactly) will make a huge mess. Just stuff coming out of the breather will make the belly messy yet not show down on the dipstick. On my AeroVee powered Fisher biplane, I routed the breather down the gear leg and stopped most of the mess. My Onex has the separator but a few drops still get by to keep the belly well lubed.

Having a polished tail-dragger, I have found that having the belly well lubed largely eliminates the need to re-polish it. :-)

David A.

So, I popped off my top mounted oil cooler tonight. The seals between the cooler and the Aeroconversions adapter looked pretty dry, and that joint was dry in general. When I went to remove the adapter from the case, the two AN4 bolts/nuts seemed a little loose. In the picture one is out and I'm pointing to the two spots.


The metric button head allen seemed tight. When I took off the adapter it was pretty wet.


This brings us to the Q&A part of the presentation. I'll do the Qs, you guys can provide the As.

1) Were the slighty loose bolts the issue? Since it is a through bolt and all metal, they could have been a lot tighter.
2) Do those seals need to be taller? They don't seem to be sticking up and have much less depth than the normal seal that is pictured there.
3) What are the chances that my oily pushrod tubes are from this leak?
a) It was very oily on the case and underneath my oil cooler tin
b) There was oil on bottom of the cylinder and the super tin - would low pressure oil from the pushrod tubes shoot up there?
c) The other side, with no oil cooler adapter, shows no oil. Nice and dry.

Not much interest in my questions, but here are my discoveries. First I used nylocks on the AN4 bolts - that seems wrong. Second, I ended up going to the next size down bolt, and one instead of two washers. That makes the bolt length a half size shorter. It's possible the nut had bottomed on the shank of the bolt.

I've decided to fix this leak and then observe the right side pushrod tubes. This is the only way to know for sure if they are leaking or being anointed from above.

Bryan;
Good practice is to never use nylock or other 'plastic' type thread lockers anywhere under the cowling.
Any lock nuts used there should be of the 'mechanical' type all-metal which are slightly more expensive but a whole lot safer.
Same goes for tie wraps used to anchor anything that is jeopardized in the event of heat failure. Critical anchoring should be done with Adel clamps.
Oil leaks are a PIA, but unfortunately a part of aviation. My old mentor used to refer to them as 'external lube systems'
Joe

Joe,
I agree. The nylocks were a mistake. They are out of there and in the trash!

Joe,
I agree. The nylocks were a mistake. They are out of there and in the trash!

Funny, the bolts that hold the case halves together have nylon lock nuts! Likely the bolt bottomed out before the gaskets were compressed.

wlarson861 wrote:Funny, the bolts that hold the case halves together have nylon lock nuts! Likely the bolt bottomed out before the gaskets were compressed.

... and the bolts just about barely get into the nylon. It could be that I didn't tighten them enough. This time around I thought the best approach was to flatten the adapter to the case, whatever it took to compress the seals to that point. I didn't use a torque wrench this time.

Bryan Cotton wrote:

wlarson861 wrote:Funny, the bolts that hold the case halves together have nylon lock nuts! Likely the bolt bottomed out before the gaskets were compressed.

... and the bolts just about barely get into the nylon. It could be that I didn't tighten them enough. This time around I thought the best approach was to flatten the adapter to the case, whatever it took to compress the seals to that point. I didn't use a torque wrench this time.

The lack of "two threads showing" seems to be standard. And it drives every AP who has looked (and myself) crazy!

Well I did a ground run after reinstalling my oil cooler. Oil everywhere. Two trips to the store for kitty litter. Maybe I should have gone electric.

Time to blame the cooler itself?