More M42 Issues

[c0rbin9]

As some of you may know, I bought my 318is a year ago with some pretty major issues - worst thing was overheating slightly. Those issues have since been fixed, but today during the oil change something gave me cause for concern again.

There were 1mm long shavings all over the oil filter, they looked like hairs, about 1-2 mm long, some silver, some copper. On top of that, when I first got the car I had an oil analysis on it and they found high lead and copper, indicating bearing wear. At this point it just seems like a matter of time before the engine blows.

Does anybody know of a way to halt the damage? What would cause accelerated bearing wear like this? The car was neglected for some time before I got it, but it has been running fine lately.

[e30sh]

If you don't have access to an oil pressure gauge, get the engine hot, put it in gear and lug it to see if the oil pressure light flickers at low RPM.


Push / pull on the crank damper to check crankshaft thrust wear. I've seen them with 1/8" endplay still running. Odds are it's the 180 deg thrust bearing that's going.

[bmwman91]

Yeah my bet would be on the thrust bearing (thanks, BMW, for cheaping out and only using half a shell). The #1 piece of advice I give to all M42 owners is to never, EVER, start the car with the clutch pedal depressed. Zero oil pressure combined with 250lbs+ of axial force on the thrust bearing is a recipe for trouble.

[c0rbin9]

I'll try to check oil pressure/crank play.

bmwman91, I've seen some of your past posts evangelizing about the shameful half shell bearing, and since then have made an effort to never start the car with the clutch pedal depressed. So there's that.

Since the crank seems so sensitive, this couldn't be related to engine/tranny misalignment, could it? Just a thought, my engine mounts/front subframe are shot, wouldn't be surprised if the engine isn't misaligned.

[bmwman91]

I cannot imagine of any reasonable way by which an engine-tranny misalignment could lead to metal shavings in the oil, with the engine still being functional. Sure, if the bellhousing got bolted up wrong and it was off a bit, the clutch disc would be eccentric to the PP/flywheel and crank center, making weird forces on the rear main bearings. But if the tranny was bolted up properly and the engine mounts are just sagging, it isn't like the tranny will move relative to the block.

The only other major source of metal shavings in an M42 that I have personally come across involves a failed/failing timing case assembly. But, you would know damn well if that was going out because it would sound like a diesel (pistons kissing valves!).

Which oil are you running. At this point, the only oils that I will ever run are full synthetic Mobil 1 15W-50 or synthetic Castrol 10W-60 TWS. These old engines with their flat tappet lifters and integral oiling arrangement in the bottom end require an oil with high ZDDP content (or similar additives). The M1 15W-50 has the highest ZDDP levels of any off the shelf non-race oil, and M1 even publishes a technical data sheet for their synthetics giving composition data. The Castrol stuff is what many/most of the current M-series engines use IIRC, and it is very protective, BUT it is like $20/qt and it seems to leak through paper gaskets like they are not even there lol.

A coworker uses this stuff in his old, high mileage German engines and swears by it.

https://products.liqui-moly.com/oil-additive-5.html

It certainly can't hurt, but I am usually a bit skeptical of "miracle additives" that people swear by. But, he has owned and wrenched on at least a dozen old German cars and they always seem to run pretty well, so maybe this stuff helps lol. My M42 is practically new (~12K miles since being built) so I don't really feel a need to use it.

[c0rbin9]

If you don't have access to an oil pressure gauge, get the engine hot, put it in gear and lug it to see if the oil pressure light flickers at low RPM.

I started it from 3rd gear (cringe) and the oil light didn't go on, so... pass?

[benihana242]

I like M1 5W-50 - That's what the 911 guys run - So that's good enough for me. I've thought about 15W-50 - they have it at my local auto-store - but the rational for 5W-50 made more sense - stress the components a bit less on start - but have adequate lubrication when hot.

Metal shavings in the oil - Could be a bunch of stuff - how is the car running? Have you pulled the valve cover and taken a look? Check out your timing chain etc etc. Also check out your oil filter/housing - the little valve inside. Why not pull a sample of the oil and send it to blackstone labs? Sounds like a good opportunity to also get a magnetic drain plug.

[c0rbin9]

I mentioned in the OP that when I first got the car about a year ago, I did send a sample in to Blackstone, they found high levels of lead and copper. The shavings in the oil filter is just more evidence.

Running Shell Rotella T6 15W-40.

[benihana242]

Oh yeah - I see that now - sorry for missing it!

I would pop your valve cover off - check out what's under the lid - maybe it's something easy/obvious.

The bright side is an M42 can be had for pretty cheap or you could do a swap if you're feeling ambitious. I've always wanted to do an S14 in mine - but those are kind of in the stratosphere at this point.

Short term - get a magnetic drain plug - if there is metal in there capture it rather than letting it circulate.

[c0rbin9]

Checking under the valve cover is on the agenda - thanks for the reply. : )

[TobyB]

get a magnetic drain plug

Good for steel chunks, less so for aluminum, lead and tin...

t

[e30sh]

I started it from 3rd gear (cringe) and the oil light didn't go on, so... pass?

Car should already be running. Apply hand brake, put in gear and bring engine rpm down by slowly letting off the clutch without stalling the car. That's when the oil pressure light will come on if you are close.

If I remember right the factory light glows at 7 psi and below. One would hope you are closer to 15 psi at idle.

[ahlem]

You may also be kicking up stuff that's been sitting in the bottom of your oil pan for a long time. There are creative ways to flush out the pan without removing it.

[e30sh]

When you drop the lower pan to check for loose bolts, look up into the pickup tube. I've seen small chunks of the plastic timing chain guide in there.