Rear main bearing oil seal

[Dave Mann]

I fitted a lip seal to the rear main since when it leaks like a colander, the flywheel boss runs true and is as smooth as a baby's bum and yes the oil thrower is fitted, so what is wrong?

[Alan]

Is the flywheel boss undersized?

[Steve Jones]

Happened to me once and the answer was as Alan suggests. From then, always fitted the boss with an appropriate speedi-sleeve and never had another problem.

Steve

[Dave Mann]

No it's within the size range for the seal

[Peter Naulls]

Both of mine leak copiously too. Looking forward to the solution!

[Tony Press]

Silly question- seal is the right way around ?

[dickie65]

Likely that the flywheel and seal plate are not concentric.
Also check the drain hole in the housing is in the correct place and not blocked with sealant.

[Brice]

What possibly helped me, was to ensure that the crankcase was able to breathe (pipe connected to the oil filler tube that leads away to the side of the car) this seemed to take the pressure away from the modern lip seal/speedy sleeve arrangement (no oil thrower) and reduce oil leaking from the bell housing drain hole.

[Dave Mann]

I checked for run out of the flywheel boss, less than 0.001", getting in to check concentricity of boss and seal is somewhat difficult. The engine has a crankcase vent to the air intake giving a depression of 3/4" water gauge.    

[Steve Bryant]

Since crankcase ventilation of engines such as ours are so important, I modified my side cover with a chamber and pipe to road draft the fumes under the rear of the bell housing. It has yet to be tested but I'm confident it should work well.
   
Stephen