Timing Gear pics - tell me how it looks

[irish44j]

Finally opened up the timing case on the M42 that's going into my early 318.

Already knew I need new main sprockets (which I have acquired already), but hopefully you guys can take a look at a few things and let me know how they look and/or how to check their condition

First, the lower sprockets. One looks very good and the other has very sharp points on it. I assume they both should look like the upper one, correct?



Here's the full case open. I do have one tensioner that has low wear, but is there any way to tell the wear on the tensioner/chain guides from here, or will I only know once I take them off? Also note that there are no pieces of the guides/tensioner in the case, so they haven't broken or anything.



This is the profile gasket? It looks to be sticking out a bit.



but on the inside all the way around it is pretty even. Looks to have a seal. Thoughts?



anyhow, thanks in advance for the inputs.

[bmwman91]

- The crank sprocket has sharp looking teeth when new. It doesn't look too terribly worn.
- The little idler sprocket doesn't really wear. It just fails catastrophically at a random, usually inconvenient time. That, or the boss it screws into breaks off of the timing case.
- The cam gears are worn out (sharp points, should look like the idler sprocket).

Other thoughts:
The entire timing chain system looks original. Updated parts for later M42's & the M44 have plastic+rubber guides, rather than the metal+rubber ones in your photos. Personally, I would replace EVERYTHING just to be safe.

The profile gasket is a little odd that it squished out like that. Replacing that is a real pain in the butt since you either have to pull the head, or remove the timing case. Head removal is probably easier, to be honest.

[irish44j]

yeah thanks - I noticed that it was the old-style chain guide too, so I'll replace that for sure. I have a new-ish tensioner piece as well, and a new upper guide.

How involved is just pulling the timing case without pulling the head, since I'll have all the sprockets/guides out anyways?

[bmwman91]

Good idea. If in doubt, just replace everything since a new engine is a lot more expensive!

You definitely can remove the timing case and put it back. I have done it myself a few times, although it is a real pain. First, you need to get the oil pump gear aligned with the crank. Then the real run starts.

Toe-in the top of the timing case with the profile gasket. I HIGHLY recommend buying some 0.003" brass sheet stock (needs to be the width of the head by ~3" ), lubing it and the top of the profile gasket with silicone grease and then having that between the gasket and head so the gasket can slide into place. It is later removed with some vise grips (remove the kidney grille and reach through there to pull).

Anyway, with the top toed-in, you need to start trying to get the oil pump gear up onto the crank. It can help to get a couple of long bolts in along the top, loosely, and then use a jack to push the timing case up as someone else pushes the bottom in. Again, the pump gear has to be aligned or it won't go onto the crank.

Once it is all bolted into place, pull the brass sheet out and you should be good to go. Check all four sides of the inside of the profile gasket with your finger to make sure that it is properly seated around the water passage.

[irish44j]

thanks for the information. I may hold off on the profile gasket since this is just for my rallycross beater and it seems fine on the inside of the passage. If it goes....well, not like I need to drive the car everyday

I'll replace most everything else, as suggested.