Coolant leak

[OriginalSterm]

Going through our new 318is Champcar and found a coolant leak in the lower front passenger side of the engine. What's the likely source of this leak?

[uturn]

Profile gasket.... not really the gasket itself but pitting of the cylinder head or lower timing case where the gasket sits.

[OriginalSterm]

Great. Is there a way to do this without removing the head?

[bmwman91]

You can definitely remove the timing case without pulling the head, but it is a pain in the ass to get back together. I have done it a couple of times. Having also pulled an M42 head, I would say that it is almost the same amount of work, although there's no machining needed if you leave the head on.

If you are going to pull the timing case, I highly recommend swapping to a 1994-1995 M42 case since it eliminates the main design weakness in the E30 M42...the deflector sprocket. It is a direct bolt-in, as long as you get the corresponding updated case-to-block gasket. You can also replace the oil pressure relief parts in the bottom of the timing case since those can seize (if they use the old metal plunger...if the plunger is plastic, then it is probably OK). Of course, if you are in a regulated racing class, maybe you can't do this.

Getting the timing case back in is the hard part with the head still on. I did it in a 2-day process. First, I cleaned the profile gasket groove on the timing case really well, and then RTV'ed the new profile gasket in, with a scrap 4x4 and some bar clamps to compress it a bit to ensure that it was seated as the RTV cured. The next day I put a little RTV on the top of the profile gasket and used a big 0.005" brass shim sheet on top of that to toe it in under the head, and then yanked the brass sheet out (easiest with the radiator and kidney grilles out so you can pull directly). The most critical part is ensuring that the profile gasket does not catch or become unseated, particularly around the coolant passage since dumping coolant into the crankcase is the end of the engine. It also involved maneuvering a floor jack under the timing case to get it up onto the crank snout, and it had to be done fast before the RTV got too tacky. Permatex Ultra Grey is my weapon of choice in RTV.

Anyway, it's a bitch and you might need to make a couple of attempts, cleaning in between.

[OriginalSterm]

The $400 timing case? Is it really that much better?

[bmwman91]

You can get them used for well under $100. In my opinion, anyone going to the trouble of removing the timing case should do it. The deflector sprocket is a time bomb.

[OriginalSterm]

If used is acceptable, I'll start the hunt. Thx

[fresh_TD]

If used is acceptable, I'll start the hunt. Thx

Get a used one. This is not a wear item. I got one a couple years ago for $75 shipped.

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[OriginalSterm]

Get a used one. This is not a wear item. I got one a couple years ago for $75 shipped.

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Any leads on where? Just hit up eBaY?

[fresh_TD]

Any leads on where? Just hit up eBaY?

I bought mine through a member on here. Just make a WTB thread.

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[OriginalSterm]

Is this the correct later version?

[fresh_TD]

Is this the correct later version?

If the back side looks like this, yes.



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[OriginalSterm]

Yes it does. ~$125 on eBaY.

The rest of the existing components will work with this, except the gasket to the block, correct?

[fresh_TD]

Yes it does. ~$125 on eBaY.

The rest of the existing components will work with this, except the gasket to the block, correct?

You need the metal gasket for this case.

Late m42 timing case: 11141739699

Late lower timing case gasket (metal): 11141739868

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[bmwman91]

Also, you'll want to check the condition of all the guide rails and stuff. If the big long one on the driver's side which spans from the head to the lower case is made of metal+rubber, then it is an obsolete design and should be replaced. Also note that the newer/updated guide requires a 45mm long M6 bolt, not the old 40mm one, to avoid stripping the threads in the head.