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Old 03-12-2013, 10:50 PM   #144
because I can
Joined: Sep 2010
Location: San Francisco Bay area
Oddometer: 9,116
Originally Posted by Kai Ju View Post
Just a couple of observations regarding the RMS installation
When I first started as a BMW mechanic about twenty years ago, after having wrenched on Japanese bikes for the previous twenty years, I was taught to install the RMS flush with the case and bone dry on the sealing surface.
The flywheel side seal surface is cleaned and left completely dry as well, with the explanation given that some of the Teflon on the RMS will transfer to the seal surface on the flywheel forming a Teflon to Teflon seal.
I've never had one come back leaking, including the one I just installed a couple of months ago when I installed my lightened flywheel.
Can anybody else confirm these instructions ? Either from anecdotal evidence or some sort of Service Bulletin or BMW training classes.

Back to Tin Woodman's dilemma, I believe that leaving the seal sitting proud is the cause for the crank locking up, which will reveal itself with the magic marker check if I'm correct.
The seal's OD needs to be lightly oiled so that it can slide in without rolling rubber ridges back in this case. Just like all seal OD's made of rubber, it should be lightly oiled. It also helps to chamfer the seal boss edge as far as not rolling back the RMS's OD ridges.

About the only rubber OD on a seal that I don't oil is oil sight glasses on oilheads and whatnot. They are looking for ANY excuse to blow out. I lubricate them with quick evaporating contact cleaner and stick them in FAST before it drys. It helps melt the rubber in tight as it evaporates!
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