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rear main oil seal


Freshman Member
I've read several old posts about the usual oil leaks of the rear main. Has anyone actually installed the aftermarket oil seal kit in a BT7, as seen in Moss catalog? Did it work? I have my engine stripped to bare block and I would like to solve this problem when I re-assemble if possible.


Senior Member
I personally haven't installed one, but after hearing and reading quite a bit about it, I personally would do it, and would recommend it as "the way to go" as long as you have the engine out. From what I understand, its not that difficult a job to do, and the results are significant. You may want to look up a past thread on this issue, I wouldn't doubt it if you'd find info in the archives of this forum.

David Z.

John Turney

Country flag
I installed one in mine. Now I know for sure that the leaking oil is from the transmission, even under hard acceleration.
(I can also tell by the color).


John, BN4


Luke Skywalker
Country flag
I installed one in my car. It involved drilling 4 holes and using a tap to put threads in the holes. I bought mine at British Parts Northwest. https://www.bpnorthwest.com/

I don't think it is hard, you need to be able to use a drill and tap.



I just completed installing a rear oil seal kit last month. Since you have the engine out of the car, now would be an excellent time to do it. The instructions say you can install it with the engine still in the car, but I wouldn't recommend it. Here are a couple of tips that might help.
1) The screws supplied with my kit were metric, rather than by a metric tap that I'm unlikely to use again, I went to the hardware store and found an identical screw in US thread(10-32). While your there, buy about six 1/8" drills
2)Enlarging the hole in the engine backplate was quite a task. I tried all kinds of saws, electric and air powered grinders, but they hardly touched it. Here's where all those drills come into play. After you scribe a line into the backplate useing the pattern supplied with the kit. Put the back plate into a vise ( a drill press would probably be best) and start drilling your way along the scribed line. Every time you begin to drill a new hole, try to get as close as you can to the previous hole. If you overlap the holes too much, the drill will suddenly slip into the adjacent hole and break. Eventually you will make it to the end. (About 1 hour) If your lucky, you will be able to break out the piece with a hammer, I had to use a saw in several places to get it out. Now get out your hand file and start smoothing out the edge. The work is very tedious, but it can be done in about 2 plus hours, including the drilling.
Go for it! Sky
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