M42 Timing chain guide rails

[ThatOneEuroE30]

Yes. It happened to me. The stupid deflector sprocket snapped off of the timing case. The casting must have cracked when the original sprocket blew its bearing, but I did not notice, so I wasted $160 on a new sprocket only to have the engine take a dump on me a year later.

At this point, my recommendation to ALL E30 M42 owners is to swap in the 1994-1995 M42 timing case. It eliminates the costly and failure-prone deflector sprocket for a plastic guide. The late M42 timing case is more or less a direct bolt-in. Just check RealOEM for the late E36 M42 for the proper gaskets and such since (at least) the case-to-block gasket differs. While you are doing it, also replace all of the oil pressure relief valve parts (spring, plunger, etc) since the original E30 design was also prone to major failures, and an updated set of parts was issued in the E36. That right there takes care of 2 out of 3 of the M42's most common faults.

The 3rd fault is the half-shell thrust bearing on the crank. Basically, never ever start your car with the clutch pedal pressed down because you are putting 300lbs+ of force onto that small thrust face with zero oil pressure. The ideal fix is to install two thrust shells for full 360 degree coverage, but that is a major project in itself.

As you know i just did the timing stuff and kept my early m42 parts just for the sake of getting it done in a timely manner and keeping it simple. I didn’t do the oil pressure valve though. Your third point makes me curious about my thrust bearing as the owners before me who were the soul owner of the car never used the e brake and just parked it in 1st gear.

[e30s50dan]

I plan on rebuilding my m42 this winter.found a z3 engine locally cheap.i need to pick this up quick for the front timing parts.
I also just got a hell of a deal on a jbracing light flywheel and clutch combo and all related parts with it

Now if I can get the body finished soon......

[e30s50dan]

Btw,does anyone have or know a list for the front m44 timing parts for the m42 conversion?

Or I will refer to realoem

[bmwman91]

Your third point makes me curious about my thrust bearing as the owners before me who were the soul owner of the car never used the e brake and just parked it in 1st gear.

Hard to say. But in general, I would say that if crank end play is not currently causing problems, then things probably aren't in too bad of shape. How bad it is for the car to start it with the clutch down could vary a lot. Winter climates, good or cheap motor oil, timely oil changes, all of those sorts of things probably influence the wear rate on the thrust bearing too.

[ThatOneEuroE30]

Hard to say. But in general, I would say that if crank end play is not currently causing problems, then things probably aren't in too bad of shape. How bad it is for the car to start it with the clutch down could vary a lot. Winter climates, good or cheap motor oil, timely oil changes, all of those sorts of things probably influence the wear rate on the thrust bearing too.

Thats true. There was no play on the crank when i was doing the timing system. They always had it serviced at the BMW dealer ship so I’d say it only had BMW oil put in it. The car feels amazing now that I did all the work to it. I have fallen in love with the little m42 even more.

[bmwman91]

Cool. Yeah, in that case you probably do not need to worry about it too much, and if you start the car "properly", something else is likely to fail before the thrust bearing does haha.

[ThatOneEuroE30]

Cool. Yeah, in that case you probably do not need to worry about it too much, and if you start the car "properly", something else is likely to fail before the thrust bearing does haha.

I did just notice that my lower timing cover is leaking some how. And i wonder if its not from the shitty victor reinz gasket cause i used erling curil T as a gasket sealer and a good amount of it along with pilots to hold the gasket and cover in place while i got it snugged up with the actual bolts and then removed the pilots and installed the remaining bolts. The timing gasket i got was a weird 1 piece gasket for the top and bottom covers together

[bmwman91]

How bad is the leak, and where does it look like it is running from?

A common spot is on the passenger side where the 2 rubber profile gasket ends meet.

I would be surprised if the actual cover gaskets were leaking, unless you applied a heavy coat of sealer on them and they squeezed out as they were clamped down (only put a thin coat of sealer on those thin paper gaskets, or none at all).

The other common leak source is the oil filter housing. I have found that reinstalling that on the timing case requires immaculate cleanliness, a thin spray of gasket sealer on the paper gasket and a tiny bit of silicone assembly lube on the o-ring. The o-ring in particular is the main leak culprit since it requires a super clean, smooth and paint-free bore to seal into. That round bore is also the main clean-oil galley into the engine, so it needs to be super duper clean anyway.

Besides that, the oil pans can leak if crappy paper gaskets were used.

[ThatOneEuroE30]

M42 Timing chain guide rails

How bad is the leak, and where does it look like it is running from?

A common spot is on the passenger side where the 2 rubber profile gasket ends meet.

I would be surprised if the actual cover gaskets were leaking, unless you applied a heavy coat of sealer on them and they squeezed out as they were clamped down (only put a thin coat of sealer on those thin paper gaskets, or none at all).

The other common leak source is the oil filter housing. I have found that reinstalling that on the timing case requires immaculate cleanliness, a thin spray of gasket sealer on the paper gasket and a tiny bit of silicone assembly lube on the o-ring. The o-ring in particular is the main leak culprit since it requires a super clean, smooth and paint-free bore to seal into. That round bore is also the main clean-oil galley into the engine, so it needs to be super duper clean anyway.

Besides that, the oil pans can leak if crappy paper gaskets were used.

Appears its coming from the passenger side lower part of the timing cover. Im seeing a good amount of oil. But it doesn’t appear to be coming from the profile gasket that the two housings meet at cause there isnt any oil how ever it could be just because of the oil on the ac compressor.

I did however forget to put rtv on the profile gasket just the cover gaskets

[RotCaboy]

The Golden Rail

Just want to confirm. My buddy and I successfully replaced the m42 timing rail (metal & plastic) with the beck arnley z3 1.9 year #0241997(plastic). Everything lined up perfect and his car is now running quiet and smooth again. Note two things, Z3 rail is more beefy, & it Was missing the set screw which is the cylindrical adjuster with two notches on the surface facing forward. If you're not sure what I'm referring to look up the most current (and most expensive) rail. The "set screw" comes on the $248 dollar part. Rock auto has the best price @ $69.99 but you will need to get that adjuster from Bmw (can't find the pn). Napa is the next best price @ $138 for the older part number : 1131173447. Hope this helps! Cheers-

Has anyone actually figured out what part numbers are required, or where we can purchase this? I am getting ready to do the timing case upgrade on my '91 m42 to the new style case and this insanely priced rail is the only piece I don't have nailed down.

I have found the new rail at Rock Auto (#0241997) but I can't find the missing cylindrical adjuster that goes on the new rail.

[TakiM3]

Yeah no clue man. I was able to snag one off a car in a salvage yard thankfully. It’s reasonably easy to get at (basically removing the upper timing cover) to get it if there’s a E36 318i lying around in a nearby yard.


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[bmwman91]

As far as I know, the adjuster is not available separately.

Also, and you should probably re-measure to confirm this, but the threads are M12x0.75. This is a bit uncommon, but there are dies out there. I cannot really find any that say they are for cutting initial threads, but there are a number of inexpensive rethreading dies out there. You may be able to get away with buying one and using it to make one adjuster from a steel rod. That just leaves you needing a drill press to bore a ~6.5mm ID hole (again, going on memory here, you should double check).

Assuming I recall correctly about the threads, you can get a die here:

https://www.mscdirect.com/product/details/79771580

Plain carbon steel rod, which I think would allow threads to be cut into it reasonably well with a good threading lubricant:

https://www.mcmaster.com/#8920k34/=1dn279p