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Berck
Berck Reader
8/30/22 8:57 p.m.

Crankshaft end play on the new engine: .005" measured on a dial gauge.  I can't find any E30-specific specs, but that seems reasonable on other engines?  More BMW frustrations--There's nothing in the Bentley manuals about rebuilds or specs like crankshaft end play.  Is there an actual factory service manual available for these things, or is that in German?

So, yeah, my 1/8"+ end play on the old engine revealed a totally destroyed thrust bearing that in turn trashed the crankshaft.

It's, of course, trashed on the flywheel side.  I wonder how much of this can be attributed to running an E36 M3 clutch on an M42?  The pedal didn't feel heavy at all, but it's got to have more clamping force than the M42 clutch did?

In any case, the valve failure was just the first thing to go.  I don't know how long you can run with no thrust bearing or what the failure mode is, but I'm guessing I would have found out in short order.

I note that new bearing sets come with a 360 degree thrust bearing shell, instead of the 180 degrees BMW saw fit to provide initially.  This makes me wonder if it's worth doing this upgrade since I'm going to pull the new engine apart somewhat anyway.  If it were simply a matter of buying a bearing set, pulling the crank, putting the bearings in and bolting it back together that would be fine.  But, from what I can tell, that's now how this engine stuff works.  There's 3 different colors of bearings... you have to put the yellow ones in with some plastigauge, measure the clearance, then order different bearing colors based on the current clearance.  This sounds like something I'm sure to screw up?  Can't I just replace the existing bearing with one of the same color, or do the crank journals wear?  Could I do just the thrust bearing?  Even better--could I do just the bottom half of the thrust bearing, which is the half that's missing the thrust facing?  Then I wouldn't have to pull the crank and buy new rod bolts and such.

Berck
Berck Reader
8/30/22 9:13 p.m.

Hmm...  Bimmerworld sells just the half I'd need.  https://www.bimmerworld.com/Engine/BMW-Engine-Internals/Lower-Thrust-Bearing-60mm-White-BMW-11211705817.html

The photo is wrong and the description says "upper" even though the title says "lower", but I'm leaning toward just buying this, popping it in and hoping for the best.... 

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
8/31/22 4:49 p.m.

In reply to Berck :

Of all the BMW engines that I have put new crank bangs in I just ordered the OEM size and put them in and they all were within spec on the plastigauge. Unless there is some sign of excessive wear that's probably what I would do. Also yes the 360° bearing is the fix to the problem of premature thrust bearing wear on the crank.... Kind of amazed it was never retrofitted prior to your getting that engine!

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
8/31/22 4:50 p.m.

That reminds me that the one I just dropped into my project car I never opened up the check the thrust bearing..... :/ Ill juat roll the dice lol

Berck
Berck Reader
8/31/22 4:55 p.m.

Okay, cool.  I'll just replace that lower shell and call it good.  Might want to at least check the end play on yours before you send it?  I'm stuck on the fact that replacing the the bearing isn't that big a deal, but you have to catch it before it trashes the crank.  Any idea what the eventual failure scenario is?  I'm guessing mine ran for quite awhile like this.  I'd guess that eventually the metal from the crank destroys other bearings? Maybe the piston skirts start scraping the cylinders when you press the clutch, but it probably takes a long time?

Berck
Berck Reader
8/31/22 4:57 p.m.

Also, what's your vote on whether replacing the 2 bolts on the crank bearing caps is necessary?

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
8/31/22 9:46 p.m.
Berck said:

Okay, cool.  I'll just replace that lower shell and call it good.  Might want to at least check the end play on yours before you send it?  I'm stuck on the fact that replacing the the bearing isn't that big a deal, but you have to catch it before it trashes the crank.  Any idea what the eventual failure scenario is?  I'm guessing mine ran for quite awhile like this.  I'd guess that eventually the metal from the crank destroys other bearings? Maybe the piston skirts start scraping the cylinders when you press the clutch, but it probably takes a long time?

yeah, not sure. On the last M42 I built (for my e21 project) the crank thrust bearing surface was pretty much trashed and I ended up finding a crank in better shape and just replacing it. That said, I didn't see any evidence of piston skirts scraping or anything like that, nor any evidence of metal in the oil or other bearings. They were all in fine shape. In reality, the real issue is starting the car with the clutch pedal pushed in, since there's no oiling happening. I'm generally in the habit of starting my e30(s) in neutral with no clutch - and that all goes back to having an M42 in the rally car previously and not wanting to put pressure on the thrust bearing without oiling. 

As for the one in my project car, not gonna bother. I'm not going to do a full rebuild on it, so no point in even knowing if I need to lol. It's not a race car, so figure it'll be fine. And if it blows up, I'll just put the rally car's junkyard (never-rebuilt) M50 into it and built a fresher engine for the rally car. Or something like that. 

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
8/31/22 9:51 p.m.
Berck said:

Also, what's your vote on whether replacing the 2 bolts on the crank bearing caps is necessary?

My recollection is on the M42 I did the bottom end on, I *did* replace them, per recommendation from "the forums" and because that was my first engine "full" rebuild so I wanted a lot of new stuff. Of course the irony is that I sold the e21 with that engine in it before I ever even fired it up. I did hear it ran fine at a Chumpcar race a year later, so I guess I built it ok :)

 Also, I feel like the bolts were reasonably cheap (IIRC like $50-60 for a set at the time).  That said, they didn't seem to be stretch bolts so I'm not all that sure it's necessary to replace them. In short, I have no fact-based advice to give lol. 

Berck
Berck Reader
10/4/22 1:06 a.m.

Finally started taking the "new" engine apart.  Good thing I decided to take it apart instead of just drop it in.

The top of the timing guide on the right hand side is broken off and just floating around in there.  Presumably because the weird inexplicable threaded standoff bolt thing is... just completely missing.  I'm assuming that whoever took this apart and put it back together didn't see fit to install it.

Given the giant amounts of RTV on just about everything, I'm not impressed with the mechanical ability of whoever worked on this last.  Can't wait to see what the oil pickup on this thing looks like.

I pulled the head and will take it to a machine shop to be reconditioned.  Some of the cam lobes have scoring that's bad enough that I can catch a fingernail in them, and the cam caps don't look great either.  Fortunately, all of that looked perfect on my destroyed engine, so I'll use those.  Not great:

But it makes me wonder if there were oil issues and the bearings on the bottom end are just as questionable.  I think I'll pull the one bearing cap I was planning on pulling to install the 360 thrust bearing and see what it looks like.  If it's bad, I may consider replacing all the bearings.  But I haven't pulled anything off the bottom yet.

I cleaned up the mating surface on the block, and it's... not great.  Some corrosion/pitting in places.  It's not terrible, and I assume the head gasket will still seal?

Also, a Miata trunk may not hold much, but an M42 head fits perfectly:

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
10/4/22 8:21 p.m.

That's the "old-style" chain guide I was talking about earlier in the thread. They all delaminate/break like that eventually, regardless of whether that bolt is missing or not. The updated style is made totally differently and doesn't have the problem (but isn't cheap). 

Sucks that it's broken, BUT it saves you from the tempation of saying "well, it looks fine" and leaving it in there, and then having to fix it later. 

When you pull the pan, there's a 50-50 chance you'll see a bolt or two in the oil pan. And if that's the case, the oil pressure relief valve (?) gasket probaly slid over and left an air-gap there, which would then not allow full suction of oil.....possibly accounting for oil starvation symptoms. When you put it all back together, make sure to loctite the oil pan bolts that are actually up inside the upper pan, so they don't fall out again. 

Mating surface looks ok in the most important areas for sealing, IMO.  The last few I've done I used some of the CRC spray-on gasket sealant (possibly the copper stuff, I don't recall offhand) with the HG and never had any issues. 

Berck
Berck Reader
10/4/22 8:36 p.m.

Cool. Loctite on the bolts that go into the timing case from the bottom, or just oil pan bolts?  There were no bolts in the bottom of the blown engine, we'll see what this one has in store.

I did buy all new timing chain guides ahead of time, including the two very expensive ones.  Also, I'm swapping to the later style timing case that was in my blown engine, which has different guides. The one on the left isn't even available for the original M42-style timing case, but is available for the newer style case I'm using from the blown engine.  At least, I think I have one of everything, if my googling and parts-ordering worked.  I didn't even understand that there *was* an old/new timing case thing going on until I pulled the engine I had and discovered that it very much didn't match the parts diagrams I'd ordered from.  Fortunately I was able to return the $300ish of timing parts that I'm not going to use.

A bit apprehensive about what I might find on the bottom end, which I wasn't planning on touching.  But if those bearings look anything like the cam journals, I'm thinking I'll need to do something.  Or maybe not, since they'll last long enough for me to drive it into a tree?

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/4/22 8:42 p.m.

Concur.... I don't like all the scratches on the deck, when I clean a deck I use a carbide scraper and scrape it flat, discoloration from the old gasket does not hurt a thing but scratches do.

 

BUT I have also reused MLS gaskets multiple times by cleaning them with denatured alcohol (wear gloves unless you want to get tipsy from spraying ethanol all over your skin) and spraying with a good layer of Copper-Kote.   That stuff is pretty good and will cover sins like rough deck surfaces.

Unless you're using a composition type gasket, in which case ship it.

Berck
Berck Reader
10/4/22 8:54 p.m.

Hmm.  I did clean it with 3M scotchbrite pads on a drill, which probably caused a lot of those scratches.  I've done a few head gaskets in my life and never had a problem with the visible scratches from scotchbrite.  You can't feel them.  Maybe I've just gotten lucky?  I can polish them out with a sanding block, but there's pitting that's *way* deeper than those visible scratches.  I have no idea what the replacement gasket I ordered is made of?

 

Berck
Berck Reader
10/4/22 8:58 p.m.

It feels like composite, it's definitely not all metal...

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
10/4/22 9:17 p.m.
Berck said:

Cool. Loctite on the bolts that go into the timing case from the bottom, or just oil pan bolts?  There were no bolts in the bottom of the blown engine, we'll see what this one has in store.

I did buy all new timing chain guides ahead of time, including the two very expensive ones.  Also, I'm swapping to the later style timing case that was in my blown engine, which has different guides. The one on the left isn't even available for the original M42-style timing case, but is available for the newer style case I'm using from the blown engine.  At least, I think I have one of everything, if my googling and parts-ordering worked.  I didn't even understand that there *was* an old/new timing case thing going on until I pulled the engine I had and discovered that it very much didn't match the parts diagrams I'd ordered from.  Fortunately I was able to return the $300ish of timing parts that I'm not going to use.

A bit apprehensive about what I might find on the bottom end, which I wasn't planning on touching.  But if those bearings look anything like the cam journals, I'm thinking I'll need to do something.  Or maybe not, since they'll last long enough for me to drive it into a tree?

ah ok, you're using the e36 timing case with the serpentine belt setup, rather than the e30 setup with three separate belts. The e36 case is said to be more reliable due to the different internal setup and no idler sprocket (or whatever it's called). 

The bolts I'm talking about are the upper oil pan bolts that attach it to the block. Theryre the same as all the other oil pan bolts, but you can only access them with the lower pan taken off, since they're inside. 

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
10/4/22 9:19 p.m.

I have killed two engines because of Scotchbrite pads.  The 429 in my first car, and a customer's 3.8 in a Sable.  THAT was when I was told to never use Scotchbrite on anything exposed to oil, because the abrasives that slough off get in there and grind the bearings away.

Gee, NOW ya tell me.

Anyway, long story short, you almost can't get too clean, I bought carbide scrapers, that is ultimately why I bought my first import car (a 4wd Subaru), and now is the time to pull the oil pan off per Josh to clean allllllll that stuff out.

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
10/4/22 9:32 p.m.

I use scotchbrite pads to clean my surfaces, but I put tape around the inside to make sure none of the stuff gets into the engine and am *very* careful. 

Berck
Berck Reader
10/4/22 11:02 p.m.

This is very good information.  Thank you.  About a decade ago when I did my first head gasket, an auto parts employee recommended Scotchbrite to clean the old gasket off, so that's what I've always done.  Whoops.

The first one was on a Miata that I got another 100,000 miles out of until I crashed it on ice.  The most recent is an Audi A4 that I still have.  It's been a couple years, but I haven't driven it much.  I'll probably go change the oil again just in case.  And order some carbide scrapers.  I suspect most of the debris wound up in the water jacket rather than the oil passages, but I probably wasn't that careful.  Don't worry, I'll blame stupid German engineering rather than my own stupidity when it does blow up:)

I was planning on pulling the oil pans anyway to, at the very least, replace the lower bearing shell with the half of the the thrust bearing BMW couldn't be bothered with.  I'll be sure to flush out all the oil passages while I'm at it.

Berck
Berck Reader
1/29/23 7:51 p.m.

I may not have been wrenching much on this thing in the last 3 months, but there has been some progress.  My goal is to be ready for attempt 2 at Rally Colorado in August, but I really would like to give Temple Canyon Hill Climb another shot this year.  First up, I got the head back from a machine shop here in town.  $500ish to have the whole thing disassembled, cleaned, decked, valves ground, valve guides replaced (worn past limits).  It looks pretty, and I'm starting to wonder if I shouldn't have just left them with the bottom end, too.  

 

I pulled the upper and lower oil pans, flipped the engine on the stand and pulled a single main bearing cap.  You know the one.

Unlike the last engine, this looks fine to me.  I was expecting it to be okay given that I measured reasonable crank end play.  I didn't get a picture, but the wear on the bearing looked quite minimal, which was a nice surprise.  I replaced it with the new updated part that has the thrust bearing all the way around.  

Bolted it together with some plastigauge and got just under .038mm.  The Bentley manual doesn't seem to mention bearing clearances at all, but a rando on some internet forum posted some and that's in range.  So... okay.  Against all recommendations, I reused the bolts, and am moving on.  Given the lifespan of the previous engine, if 2 main bearing cap bolts being reused takes out this engine, I'll be shocked and go find a 6 cylinder.

Removed the early style timing case to replace it with my newer one.  Some pretty good corrosion behind it, beneath the water pump.  Not worried about this at all, since the mating surface is still fine.

Thanks to Josh for this idea.  Should have done it for the stuff in front, too...

Newer timing case from the old engine bolted up:

 

I intend to use the steel lower oil pan my car came with.  It's rare, will dent (is dented), and it turns out, is shallower.  Since my skid plate has basically zero clearance to that oil pan, I'd have to modify it to use the stock oil pan even if I wanted to.  It's enough shallower, that the oil pickup was modified:

 

When putting this stuff together, I noticed that the oil pan has a nice witness mark from the oil pickup hitting the pan.  The dent in my oil pan apparently took a rather small clearance and made it negative.  The oil pickup appears to have cracked in protest:

 

I put the steel pan on my garage floor and hammered out the dent.  I modified my unmodified oil pickup (other than the cracks), and then got my wife to make me some playdough, since I don't have any modeling clay or anything else appropriate to measure the clearance.  That worked great, and...  there's only about 1/8" clearance.  This seems still too small, but further modification of the oil pickup would involve a custom screen solution.  The steel pan isn't terribly flat on the mating surface, so I'm thinking that doubling the gasket will get me another 1/16" of an inch and make it more likely to seal.  Open to opinions/options, here...

irish44j (Forum Supporter)
irish44j (Forum Supporter) MegaDork
1/29/23 9:26 p.m.

No real advice on the oil pan clearance part, but just came here to say that the engine looks great!

 

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