Thinking about installing an BMW M6 engine in my Z

[wheee!]

On the track it's not "if", its "when"...

Bummer the Bimmer's a Binner... here's hoping you can fix it easily.

[RyanT67]

That's really awful news to hear, Chris.  My diesel crank was damaged when my 3.0 stroker engine spun a bearing a couple of years ago, and I had a crankshaft shop in Toronto repair it by welding and regrinding the journals for oversize (or is it undersize?) bearings.  Ran me about $500 CDN.  I'll see if I can dig up the name of the place for you - I'm pretty sure the name had the word "Crankshaft" in it actually...  

Bit of a headache though, given the confidence you had in the engine health and the professional rebuild that was done on it not so long ago.  Wonder what would have caused the bearing failure?

[grannyknot]

1 hour ago, RyanT67 said:

Wonder what would have caused the bearing failure?

Soon to find out, I hope it is just a bearing. I'm thinking I might get the oil in the pan analyzed in case it holds any clues... other than shards of metal of course

[Captain Obvious]

Yeah, I'm hoping for some interesting forensic discovery... I'm just hoping it's not too gruesome.

Any possibility that you starved something for lube with the oil pan changes you made?

[grannyknot]

7 hours ago, Captain Obvious said:

Any possibility that you starved something for lube with the oil pan changes you made?

Very possible but I don't see how at the moment. I got my engine hoist back yesterday so will remove the hood today and start prepping to pull it.

[grannyknot]

Got the engine out today, here is what's in the oil pan,

removed only one main bearing so far #4 in the middle and it is perfect,

but the conrod bearings on either side of it are spun,

The oil pump is in good shape, only a bit of soft metal transfer from the bearing material and it comes off with a fingernail. Glad to see my modification to the pump wasn't the problem. So something must be clogging oil passage way in the crank.  I'll have to tear it down, see if the crank can be saved, so far from the bottom of the engine the cylinder walls look good so maybe I can get away with just replacing the bearing shells.

[Captain Obvious]

Good thing you shut it down so quickly.

I'm really curious as to why something like that would happen all of a sudden happen.  You pulled this engine from one of your cars, right? Car was totaled, but engine was fine?

[rturbo 930]

Reminds me of what I went through with my E30. The old, high miles motor developed a knock, I pulled it out and replaced it with a refreshed low miles motor - new gaskets and all new bearings. Started knocking within 2k miles. No clue why. I've never had a car with so many engine issues (still doesn't idle right, two engines later - can't figure that out either).

Looks like the damage isn't too bad at a glance. Good luck rebuilding.

[grannyknot]

On 8/26/2017 at 9:33 PM, Captain Obvious said:

Good thing you shut it down so quickly.

I'm really curious as to why something like that would happen all of a sudden happen.  You pulled this engine from one of your cars, right? Car was totaled, but engine was fine?

The engine was rebuilt by a BMW pro, I reassembled it and then drove it for 4000 mile then I kept the engine and tranny and parted out the rest of the car. So far I have put a little less than 1000 miles on it while it has been in the Z.

Built an adapter plate so I could mount it on the engine stand, there is no bearing material up near the cams so that is a good sign, I have all fall and winter to fix it so I'll go slowly.

 

[grannyknot]

Removed both cams today and the journals and bearing surfaces are perfect, no damage and the cams are farther away from the oil pump than the conrod bearings. There has to be an obstruction in the oil line going to the crank.

On these engines the head consists of to two pieces, the top piece is the timing or cam box and the lower piece holds the the valves and spark plugs, I'll have the lower head off tomorrow.

[Careless]

20 hours ago, grannyknot said:

the cams are farther away from the oil pump than the conrod bearings.

while that is physically true, the more important thing to keep in mind is the oiling priority of the engine. the technical service manual should have an arrow-drawn diagram in the engine lubrication or oil pump servicing chapter that shows what gets oil first... it's not the same for every v6 or i6 or v8, etc- even from the same manufacturer. they've all experimented a lot in the last 40 years.

some dual overhead cam motors see oil at only one the cam first- before anything else, then it gets pumped down to the crank shaft, and then back up to the other camshaft. some see oil go through the entire crankshaft, and then fed up to both cams through the rear of the motor, and then oil is fed through the hollow cams, lifter guide plates/valve cases, or oiler bars- and any residual oil is then dumped into the timing cover.

race-minded engine designs are typically crank-priority oiled. it's a safe bet. but I would check to be sure.

 

I hope you replace the oil pump while you're in there. there is too much of that bearing in the pan for it to not have gone through the pump at least once (how many times it went through would depend on where the oil filter is in the priority oiling system as well)

 

Edited August 30, 2017 by Careless

[grannyknot]

Finished the tear down, the head looks good, can't explain why cyl #1,2 and 3 appear oily compared to #4,5 and 6, there is no scoring of the cylinder walls and all the rings are in good shape and the pistons all look dry.

So conrod bearing #1 spun, 2,3,4,5 did not spin but are trashed, 1-5 bearing shells are a copper based bearings. #6, the shiny silver coloured bearing on the far right shows normal wear for 5000 miles. In fact to my eye it looks like #6 are the only bearing shells that were replaced during the rebuild. I'm going to take the block back to the builder and ask him to explain it to me. 

All the main bearings are perfect except #2 which is badly worn, I ran a wire through every oil feed line in the block and the crank and there were no obstructions, all clear passage ways.