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sparky1 sparky1 is offline
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Join Date: Jul 2014
Car: 08' 135i
Default Front main seal replacement question - 01-31-2019, 10:53 PM

Hey Everyone,

Just curious on the installation of a new front main seal.

Does the inner lips of the seal that touch the rotating crankshaft go inside the block? or should it stick out towards the end nub of the crankshaft?


in - [>=

out [<=

terrible way of explaining it, I know, but [ = the actual outer part of the seal, that's going to go in the block anyways and has those lips on the outside. <> is the lip on the inside that sits on the spinning cranshaft and the = is the actual end of the crankshaft that you are pressing it over, that will obviously stick through the inner lip of the seal.

Just wanted to double check before I go and do my front crankshaft install

Any tips and tricks on how to not F it up with the special tools?

also, from my research, it looks like the lip should face inwards based on the pictures in this repair manual: 11 14 005 Replacing front crankshaft seal (N54, N54T)

09' E90 6MT in BSM
Mods: DCI
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RocketSurgeon RocketSurgeon is offline
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Join Date: Jan 2016
Car: e90 335i
Default 02-02-2019, 01:30 AM

The lip always points inward on shaft seals like this. That goes for axle seals, crankshaft seals, etc.
Take a close look at the seal, and you should see a little spring on the inner lip of the seal. The spring bit sits inside the engine and keeps the inner lip of the seal pressed against the shaft.

BTW, you need a little sealant on the outside of that seal or it WILL leak where the 2 halves of the crankcase meet. And the seal usually comes with a little plastic ring to protect it as you slide it onto the snout of the crank.
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