Forum » General Engine Building Discussion » Bearing Failure?

Bearing Failure?

General Engine Building Discussion

Talk about engine building here. New products, tricky questions or showcase your work - If it's engine building related it's welcome here.


Page 1
Author
67 Views

So not sure this post is in the right area but it’s both engine building and tuning related.

So I have a problem with a fresh built Bmw m50 engine which is designed for turbo. It’s forged rods, pistons, bored out, cams and so on, everything you would want, professionally built for around 900bhp. I brought the engine from someone else who had it built but never got round to installing it.

So far I have done 1100 miles in the car, three oil changes and it’s due for mapping on Tuesday. The car has a rattle on what I would call overun (this is since it was started), blip the throttle and as the revs transition to come down again I hear a rattle, I would liken the sound to a lifter noise.

So I currently have the lifters out and have found the trays to be scored (pics attached). I like to think when the engine was built the trays weren’t in this condition, but don’t know for sure. So this coupled with I have some spikes in the knock monitoring on light throttle is starting to make me think the noise might be a bearing problem as mentioned in one on the webinars.

I have attached pictures of spikes in the logs, it seems to occur across multiple cylinders though? So I’m not sure if these spikes are consistent with what you would expect to see which a bearing problem?

I have new trays and lifters ready to go in the car but don’t see the point if the logs indicate a bearing problem.

Also to add add to my confusion I have two other used cylinder heads, one does have some scoring in the trays and one doesn’t.

The engine was primed with oil before starting and these lifters that were in were supposed to be new genuine Bmw ones.

I do have some metal in the oil filter but not sure how much is normal with a fresh build, I will try and get some pictures of this and the oil.

Any help greatly appreciated

Attached Files

So here’s the pictures of oil drain pan and filters. The darker filter is the first one that was changed after 500 miles on running in oil, the lighter one was changed 500 miles after that with it running on proper oil. Lastly there is some pictures of the bucket used to drain the coolant, there’s even metal in that? I also have a video from the cars first start to showing it making the noise then, so in the webinar is mentions the bearing clearance being wrong to cause this, are we generally saying too tight?

Attached Files

There are too many variables to give you an exact answer on this, and I am not familiar with BMWs. What I can say is get an oil sample and get it analysed by a specialist like Blackstone labs. Their analysis will be able to give you a better idea what is in your oil and if it should be there.

Those lifter bores are ugly! I'd expect that sort of damage to be the result of debris in the engine that resulted from inadequate cleaning but that is just my best guess. It's quite normal to get some debris in the oil filter during the initial break in, however that shouldn't be an issue after 3 oil changes. Also by the time you've got 1100 miles on the engine it's as run in as it's ever going to be!

I'd recommend you cut the filter element apart so you can inspect it properly. If you've got a bearing issue then this will show up as copper debris in the filter. Most of the material the filter traps will be trapped in the internal fold of the pleats so you need to cut the filter material and lay it out flat to get a proper idea. An oil analysis as Philip suggested is also a great idea. Lastly if it's not too much trouble I'd just drop the sump and inspect a few bearings.

Thanks for the advice, I have cut the filter open and there was a couple of pieces but nothing major, no copper. Going to keep an eye on it. I think I found the source of the noise, the valve timing was way out, so adjust that along with good condition lifter trays and lifters and it’s gone, rather worryingly maybe this means the valves were just touching. Attached pictures of the timing at 1mm lift before and after. Leak down check comes back all ok though. So will keep an eye on the filter and get some analysis done. Any thoughts on the spikes in the knock log? Still got the odd one with the adjusted cam timing, is it not unusual to get the odd random spike?

Attached Files

The spiking in your knock data isn't normal and either indicates your gains or frequency might not be on point, or alternatively the knock control is responding to some other mechanical noise (which isn't uncommon on a race engine).