Crank scraper install -- rear cover seal trimming?


Posted this on r3v, but wanted to get more eyes on it:

I’m installing the IJ crank scraper and I’m not really clear on one of the instructions regarding the rear cover.

I’ve got a 12/86 build 325i. Apparently not all the E30/M20s have this, but the rear part of the oil pan had a little cover that bolts into the bottom part of the transmission. There’s a little rubber seal where this cover presses against the oil pan.

The instructions say that if you have this, you “trim the seal 2.5mm” to prevent applying too much pressure to the cover or the block when you bolt it back down.

I’m not clear on where/how to trim this piece. Trimming the length seems pointless… and the whole thing appears to only be a few mm deep, so 2.5mm seems like a lot to scrape off with a razor (plus, I’m not sure how you even do this evenly).

Part is #29 here:

I feel like I’m missing something easy here…



I wouldn’t worry about it. I’ve never heard of anyone having to remove material from that seal. Some folks don’t have it at all, others don’t have the inspection plate that it fastens to.

The absence of the plate makes for a quick inspection of the flywheel in post race compliance.


I agree with Scott’s advice; just re-install the inspection plate as designed. The thickness of the crankscraper has never caused me any clearance issues and I really doubt you’ll have any problem. It is important to install in the inspection plate; otherwise, you’ll get all kinds of crap, grass, dirt, rubber inside your transmission bellhousing.


Ah, good to know, thanks!

Seems odd that it’s one of the only bold/yellow highlighted instructions that came with it – “resist the temptation to install without trimming”.