n57 bad rattle, rod bearings?

[carl0s]

Girlfriend just came home saying her car is rattling. It does not sound good.
Strangely, I have been doing a lot of reading about BMW rod bearings, particularly in the V8s - I have a car with an S63tu that I'm thinking of keeping hold of for longer than I thought.
My thoughts are that there is a high chance that this is rod bearing failure here. What do you think? I have done a very basic test of unplugging a few injectors (one at a time of course) to compare the current rough-running to a cylinder-down rough running. I just did the front 3 cylinders though due to not being in a position for stripping bits down yet, but I confirmed they are running and that engine is even worse with each of those injectors unplugged.

Video:

I suppose my options are to get whatever tool is required for pulling an injector, and putting a borescope down each cylinder to have a look from the top, and/or pulling the sump and checking the con rod bearings from the bottom.

cheers,
Carl

[carl0s]

marcelN57 said:

I've decided to drop the subframe, take off the oil pan and look at it from below. Hopefully it's just a spun rod bearing and I can get away with replacing that and polishing the crank bearing surface.
Given I'm observing consistent codes for cylinder 5 balance only, I assume most likely it's that rod bearing rather than the pulley / cylinder 1. But we shall see! I'll take it apart this weekend.

Good luck. I have been contemplating the same, however I'm considering just removing the engine and taking my time, after I have checked the oil and oil filter, which will be this weekend.

[carl0s]

Thanks everyone. Apologies for the radio-silence. I have been frantically getting the stationary M6 road legal and MOTd while she drives my 125d and I talk my way out of work site-visits.
It's been a wonderful week for working on a car outside and being forced to ride motorcycle a couple of times. I feel like I've had a proper holiday from my life of working and endlessly watching people do stuff on youtube. I've been forced and kicked up the arse to do my long term project (get mill running to fix lathe top slide to skim m6 discs). Refitting the cats on the M6 was a crap job as usual and that is the last time I will ever do that job.

I should hopefully start looking at the x4 this weekend.

[carl0s]

Marcel, I will re-post your images for you.

Also, can you give a brief rundown re: dropping subframe - any shortcuts etc. The weather has picked up, so think I will do the same tomorrow. Not sure if yours in an X3/X4 too but would like to hear your experience regardless. I was going to remove bumper and pull engine but it would be good to inspect from below first.

These are MarcelN57's images:
1. Rod bearings - number 5 is spun and pretty destroyed. Rod and rod cap look fairly okay.



2. Main bearings - number 6 has lots of wear and is somewhat distorted. It was also very slightly rotated when I took them out, maybe 3-5 degree, but not so much that it would block the oil flow. It doesn't look like it spun, the outer bearing surfaces look pristine.
Number 2 to 6 are visible in the photo below.

[carl0s]

Thanks very much! I do have an engine support bar so I can use that to help.
I've reposted your photos below.


These are MarcelN57's photos:

View from above on all the straps that hold the engine (engine mount) as well as steering rack and stabilizer in place



Sub frame just coming down. It's not too heavy, I did all of this by myself.


View from below with subframe removed

[carl0s]

I have opened oil filter on our car and can confirm fine bronze particles in there. So I should either proceed to drop subframe like you have, or just remove the engine.

Think I'll inspect from beneath to begin with.

[carl0s]

Here's my oil filter insides

[carl0s]

marcelN57 said:

Now you have definite confirmation it's not an injector or something like that!

Update from my carnage:
I polished the crank surface for the #5 rod bearing (the bad one), then put that journal back together using the bearing shells from one of the other (good) rods. The plan was to measure the bearing clearance with Plastigage. However - the journal had lots and lots of play. Knock knock

So I took it back apart and measured the crank diameter at #5 rod position. It's between 49.2 and 49.5mm depending where you measure - not round and totally out of spec (49.975 - 49.994)!

Sounds like I need a new crankshaft. Which means, I need to take the engine out. At that point, it also makes sense to replace the #5 connecting rod. Which means, head has to come off... Gone the dream of a quick fix for this.

Oh dear, I'm sorry to hear that. I was hoping you (and I!) would get away with a quick fix.

I pulled pan on mine, oil was like black gloop. When I washed away the gloopy oil in the pan, I saw lots of beautiful glitter.

You can get a new forged crank from Autodoc for ~$1200 USD. Non-OEM but also not Aliexpress. You can also get one from Ali Express for half that :-) that won't be forged though.

[carl0s]

Good stuff. Thanks for the update, I'm looking forward to following along.

Our engine is nearly out. I was stopped by the rain, and I couldn't find a wiper-puller for getting the rear cowling off the car. Hopefully I'll carry on this weekend.

It's looking very sorry for itself :-)

Edited by carl0s on Wednesday 29th May 10:56