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Oil Leak BN2

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Bob_Spidell

Bob_Spidell

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Yeah, I know...

We've fixed them all in our BN2 (100M) except for one nagging leak. Oil appears to be leaking at the bottom of the bellhousing, where it's bolted up to the rear engine plate. We installed a rear main seal and there is little, if any, coming from the usual source (the hole in the bellhousing with the cotter in it). We were careful/diligent with gaskets and used a discreet amount of gasket sealer wherever it seemed appropriate.(like on the large gasket between the block and the engine plate). The cigarette-shaped felt gaskets that came in the kit that go around the rear main bearing cap seemed a bit undersized, but we used them.

Any ideas? Could the seam between the rear main bearing cap and block--with the undersized felt, cigarette-shaped plugs on either side--be the cause? We get a few drops on the floor after a 4-5 mile run.

TIA,
Bob
 
A few drops on the floor after a short run sounds great to me!

If you're not getting drips through the usual hole in the bottom of the bell housing, you probably have the rear seal dealt with OK. I would look outside the bellhousing, perhaps the rear of the valve cover. Drips from there could eventually make their way down to the bottom of the bellhousing.

Most any leak from the inside of the bell housing (rear seal, cam shaft plug, rear bearing housing, front transmission seal) is going to end up running down inside the housing and out that drip hole.

I think if you're really down to a few drops, consider declaring victory and moving on! I think that's an impressively low leak rate for a 100. Mine used to gush out a 12" diameter puddle after every drive. With a lot of work, I finally got mine down to a one or 2 in puddle and I'm happy with that.
 
It seems like a small barrier "fence" across the bottom of the bell housing with a second hole aft of it would show if the leak was coming from the front of the trans.

I've had success - leakage around a drop a week to a drop a month with a comprehensive package:

speedy seal on front pulley; hylomar on both sides of front plate gasket and front cover gasket; hylomar on both sides of oil pan gasket. Use of Permatex Aviation FormAGasket over the joints on either side of the rear main bearing cap. Seal the edges and mating surface of the rear seal kit. Seal the area around the rear cam bearing hole.
PCV valve.

see: https://www.pbase.com/stevegerow/image/97270433

Am also using an aluminum sump, which has a more rigid flange than the sheet metal one.
 
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