Hey everyone,
I recently rebuilt my transmission. My first attempt at such a job, and I used RedBeard's very helpful article. So now it shifts great, but it leaks. As I drive, tranny oil is getting all over my exhaust and leaving a smelly smoke trail behind. It looked like the oil was pooling mostly at the end cover, and on the right side, so I thought it was the speedo drive and replaced the O-ring. Still leaking.
Now I'm wondering if I screwed up those paper gaskets. When I took the thing apart, there was 1 paper gasket between the end cover and intermediate plate, and 3 paper gaskets between the plate and housing. I thought all of them had the color of oil soaked brown paper. I had purchased a Pelican transmission gasket set, and it came with 1 cover/plate and 3 plate/housing gaskets, and they were all brown. So I thought perfect! I'll just use them all.

At this point, I'm not sure what my next steps should be. Anybody want to throw some suggestions out?

Send Pic's

At first, I didn't use any sealants. about 30% of the tranny's leaked. Then I tired the VW fix, using grease on the surfaces. This _usually_ worked but...

I settled on using a non-hardening gasket sealant. I have been using "Form-a gasket", but any brand should work. I put it on both sealing surfaces.

Make sure the surfaces are clean. Buy the right tool for the job. your FLAPS will have a gasket scraper tool. Looks like a bent screwdriver with a triangle on the end. Get one, they work great. Also, I clean the surfaces with brake cleaner and dry them before applying the sealant.

James

Go to a Porsche dealer. Get the sealer that they use for the Boxster engine cases. Make sure the sealing surfaces are clean and dry. Then put the sealer on each surface as you assemble it.

No more leaky tranny.

Done this on every transmission I have built. No leaks yet.

when you use these "sealants"...do you NOT use the porsche gaskets?

The gaskets between the intermediate plate and the main case are CRITICAL to the proper pinion depth. When you take a tranmission apart, use a micrometer to measure the thickness of the gaskets that are already there. Then use the combination of the gaskets in the gasket kit to get the same thickness. Failure to do this will result in improper ring and pinion wear and NOISE from the differental.

I use the sealant with the paper gaskets to insure that the transmission does not leak. I do not put it on O-rings, though!

Note.. this stuff is NOT silicone. I would not put that on a transmission unless I was in BFE with a major leak and no gasket to fix it. And it would only be temporary. The boxster sealant is anhydrous, and never really dries. So case movement won't tear it loose.

You shouldn't use any sealant between the intermediate plate and the main case. As Clay said, the thickness of the paper gaskets here is critical to the pinion/ring gear mesh. So it makes no sense to match this thickness, and then throw in sealant, which adds thickness. Most gasket maker sealants are RTV. This will add about .001" of thickness wherever it is used. So if you have 2 paper gaskets, and you add sealant to either side and between the gaskets, you have added about .003" to your stackup for pinion/ring gear mesh.

There are some sealants that don't add thickness - such Permatex 3H, which is what is used between engine case halves. The thickness of an RTV or Silicone sealant is why those sealants aren't recommended for sealing engine case halves. So the same reasoning applies to the transmission intermediate plate where the thickness of the gaskets is critical. So if you are going to use a sealant between the intermediate plate and the main case, use a sealant that won't add thickness.

Demick