knock knock... what's that?

[cpatstone]

Originally Posted by gimp

It was never over revved in the three years I owned it. It certainly wasn't babied, but never over revved.

-- you never raced that thing, did you? I'd always assumed all the pix of the car on the autocross course were just photoshop.

[gimp]

Originally Posted by cpatstone

-- you never raced that thing, did you? I'd always assumed all the pix of the car on the autocross course were just photoshop.

LOL... I only photoshop the results.

[ASRACER4]

problems with rods will sound different then his video. rod knock from galling or wear is a much deeper sound. i would also expect to see a copper tinge to the oil if the bearings where going bad.

[xxxJohnBoyxxx]

Originally Posted by xxxJohnBoyxxx

Can you remove these metal pieces from the filter and take a picture of them on a flat surface (Macro). Also is each fold in the oil filter packed with this much metal?

This is not normal wear but I'm not sure what it is. Maybe if I can look at the metal closer I might be able to figure out what part it was...

John Smith

I hate to quote myself but I would really like to see a Macro picture of the metal if you could remove that from the oil filter. I think it would help us identify what it is even though it has been mashed up being run through the oil pump. I see copper in the oil catch pan picture too. I think you motor has very bad damage in the lower end and most likely will have a bad to catastrophic failure soon if this is not addressed.

Sorry, John Smith

[pdxmotorhead]

Originally Posted by cpatstone

Thanks Dave. PO's mechanic thought it was a rod bearing.

Two questions - for you or anyone else - do you really need to lift the motor and drop the subframe to get the oil pan out? I don't have an engine lift, but I could borrow one. Then again, if we're pretty sure it's bearing material, I'd rather do a post-mortem when the motor is out and the S52 is in.

question #2: thicker oil would be very slightly better in this situation, right? what's the thickest I can go? Suggest any additives? (will put the new oil in after flushing it with clean-but-used oil, and a new filter)

BTW, I didn't measure the cam lobes because I just can't believe that any one of them is the source of all that debris. Turning the crank by hand, you know that some parts of the cycle take more effort than others as the cam lobes compress the springs. I did notice that the chain tensioner gets pushed in a little as there's more tension on the timing chain, then goes back to where it was. Gets pushed in maybe 1/8", or less. Point is, I assume this is normal. Timing chain guides looked fine as far as I could see from the top end. I've put the thing back together, with the stock exhaust and not the aftermarket one the car came with, in hopes to pass the state inspection. And ask the guys if the car is subject to emissions inspection. 'cause that might be important...

If it was cam, I'd expect it to be magnetic material.
It also could be failure of the thrust bearing surface, that might explain the erratic RPM that the noise occurs. Trash thrust bearing would likely be rpm centric, because the crank is moving front to rear. Just a random thought....

Dave

[xxxJohnBoyxxx]

Originally Posted by pdxmotorhead

If it was cam, I'd expect it to be magnetic material.
It also could be failure of the thrust bearing surface, that might explain the erratic RPM that the noise occur, Trash thrust bearing would likely be rpm centric, because the crank is moving front to rear. Just a random thought....

Dave

That is what I'm thinking and why I want to see pictures of that metal in that oil filter to identify...I can't think of anything else but then how does a crank tap in perfect harmony with RPM, counter weight hitting a cap or something hitting each revolution?.We need to see a Marco of that metal in that oil filter and how much was in there? Was there metal in every fold of that filter?

Dump it out on a solid background and take a picture please

[pdxmotorhead]

The good thing is that the Thrust bearing "can" fail without other damage, but you still have shrapnel in the system... with that much metal in the filter, whatever it may be, the passages in the block are likely contaminated.

Time to move on to the swap LOL

[xxxJohnBoyxxx]

Originally Posted by pdxmotorhead

The good thing is that the Thrust bearing "can" fail without other damage, but you still have shrapnel in the system... with that much metal in the filter, whatever it may be, the passages in the block are likely contaminated.

Time to move on to the swap LOL

Crank thrust has to be jacked too with that much metal plus the "knock", something else hitting on that crank??? It is not a healthy motor

[cpatstone]

I looked again at the debris in the oil filter last night. The picture must show some sort of optical illusion. The bits are maybe, I dunno, .001" approx diameter? They do seem to be darker gray colored though. maybe not soot colored, but could be steel, just not shiny. Almost look like bits of timing chain rail, but the rails looked fine as far as I could see from the top end. Didn't see any interesting debris in the drained oil. More of the same.

So the car's together again, with good used oil this time, and I took it for a spin yesterday and today. FWIW: the noise is worst with no load, and at 3000+ rpm. So on the highway, with any acceleration or deceleration, you can't hear it. but right in the middle, it's audible even at 75mph.

So... at this piont, M52 for $500, or S52 for $2000? that's really the big question.

[xxxJohnBoyxxx]

I have to go with Dave on this and say he hit it and it is the thrust bearing. Go with the swap cause that crank is slowly chipping away on something inside there

[pdxmotorhead]

!! just occurred to me,, if you have the engine off, and grab the end of the crank and pull and push it should not visibly move(much) if it slides in and out it would be a sure sign the thrust bearing is gone... I have not tried this on a BMW but it works on a small block chevy and most other engines..

[familytruckster]

Originally Posted by pdxmotorhead

!! just occurred to me,, if you have the engine off, and grab the end of the crank and pull and push it should not visibly move(much) if it slides in and out it would be a sure sign the thrust bearing is gone... I have not tried this on a BMW but it works on a small block chevy and most other engines..

Mine has a wasted thrust bearing, it's qiuet, but I can pull the crank a good .080"

But yes, you can check the endplay like that on the bmw.

[cpatstone]

quick update:
Best guess was a failed bearing in the top end of a con rod. Motor was replaced with a tuned M50. Would be nice to figure out what was wrong with the M44. Cylinder head looked fine, bot on camshaft side and piston side. Oil pan had a couple of shards, biggest maybe .38” dia x thin.

Here’s the real question: Also in the oilpan was an M5 flanged hex nut. No corrosion on it, so presumably came from the inside of the motor. No marks / dings / abraision on it. No loctite/etc. Just a nice, clean nut. Thing is, where would that come from? I didn’t see anything in the RealOEM online fiche A few M6 nuts, that's it.

I haven't taken the whole front timing cover off yet as that would require taking out the main crank front bold, right? which is serious torque, right? side question --- without a tranny on the car, how would you hold the crank such that I could take the bolt out?

[xxxJohnBoyxxx]

Find a bolt that will fit through the flywheel lock hole and into the flywheel pinning location then put the bolt through and a nut on the back side and tighten it to jam it into the flywheel lock hole.

I made my flywheel lock tool with old bolts in a scrap box. You could buy them for less then $1

[cpatstone]

Update: the naked little engine block is now hanging off a borrowed engine stand... after a little fiddling such that the timing chain was out of the way and I could just freely spin the crank, ...

#2 cylinder very clearly has a gap between the top end of the rod and the piston. done deal.



Cylinder head is spoken for, but everything else from the ECU to the MAF to the exhaust manifold is available. Make a reasonable offer and it's yours.

Thanks to all who helped in the diagnosis.