n57 bad rattle, rod bearings?

n57 bad rattle, rod bearings?

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Discussion

rottenegg

605 posts

66 months

Saturday 11th May
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Sorry to see such a mess, how annoying.

This is the problem with sputter bearings, they are harder than the crank and destroy it when they run out of lubrication. Plain bearings give you more of a chance to save the crank if you catch it early enough.

Personally I would look into used engine options. The N57 is known to be not very cost effective to repair back to factory standards.

Have a look on H2 Motors YouTube channel. They rebuild N57s all the time and they go into great detail about common N57 issues. They've mentioned the heat of spun bearings can warp the block, so even a brand new crank from BMW may not save the engine unfortunately......well....not in the long term at least.

Good luck with it and thanks for sharing the carnage pics!

marcelN57

16 posts

3 months

Wednesday 29th May
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I've now taken the engine out and disassembled everything. Didn't find anything wrong otherwise. Pistons and cylinder bores look great, original cross hatch clearly visible.

I've measured the block main bearings for diameter and straightness.
- Diameter wise they are all the same and all within spec - 60.00mm 90° from the split, and 60.02mm around the split pane
- Straightness, in both axes less than 0.001" deviation which was the smallest feeler gauge I had.

Given this, I'm confident it hasn't damaged the main bearings or warped the block, or anything like that.

The only thing a bit weird I did see is that the soot pattern around the injectors appeared to look a bit different on cylinders 5 (the spun rod one) and 4 (where I swapped injector 5 with for testing purposes). Not really sure if this real or just my imagination though. But maybe injector 5 failed via some distorted spray pattern, and that somehow caused all of this?


Also, piston 5 appears to have hit the head. The QR code imprinted on top of the #5 piston is now also visible on the cylinder head, if you look closely. There seems to be no damage to the piston, wrist pin, or head however. So I assume this was a result of the spun bearing where the piston between exhaust and intake stroke made light contact.

I've decided to rebuild the engine as I can't see why it shouldn't work, and it seems less suspect than going for a used engine which I also don't know if it will last. I've thoroughly cleaned the block and all other parts. There are only very few places where remaining glitter could hide, like say in the turbo.
I'm going with OE parts for crankshaft and a few other things, Kolbenschmidt for main / conrod bearings, and Elring for most of the seals/gaskets. Most parts have arrived now and I'm about $3,500 in so far. I'm still debating whether to replace the injectors as well.

Will still take me a few weeks to get everything back together as I'm doing it evenings / weekends and with somewhat limited tools. Curious to see if it'll work out or end up being a massive mistake rotate

marcelN57

16 posts

3 months

Wednesday 29th May
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A few more details on the damaged parts:

- the old crankshaft had runout of 0.0065" / 0.165mm. Couldn't find acceptable values for this engine but it must be on the high end or outside of tolerance.
- the #5 conrod big end diameter is 53.59mm (0.01mm below spec), along both axes and most angles i tried. So seems like it took some material from the spun bearing. Not sure if someone could have machined this out, but I decided to go for a used replacement

carl0s

Original Poster:

549 posts

231 months

Wednesday 29th May
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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

carl0s

Original Poster:

549 posts

231 months

Saturday 22nd June
quotequote all
How're you getting on?

I finally got our engine onto a stand in the garage today. I pulled the engine and trans a few weeks ago and got it down into the garage, but have only today mounted it to the stand the turned it upside down.

I haven't removed caps yet but I can rattle rod caps 1 to 4 and they have probably 1mm of wobble/rattle in them, which does not look good at all. 5 and 6 are the only ones without the wobble.

carl0s

Original Poster:

549 posts

231 months

Sunday 23rd June
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Video showing the amount of play in the bottom end


carl0s

Original Poster:

549 posts

231 months

Sunday 23rd June
quotequote all
Removed rod bearings and inspected rod journals. It's fairly catastrophic, sort of as expected really.


carl0s

Original Poster:

549 posts

231 months

Saturday 29th June
quotequote all
My main bearings all look OK. Opposite to MarcelN57's. I have almost all rod bearings spun and destroyed and mains are all good and straight.



Edited by carl0s on Saturday 29th June 15:30

rottenegg

605 posts

66 months

Saturday 29th June
quotequote all
Good work chaps smile So glad to see people tackling this work themselves instead of being bent over by BMW.

Bit of a weird one with the sooting inconsistency. I only know of remaps that increase the rail pressure causing injector nozzle failure, but on standard engines, it's unheard of unless the fuel is particularly poor quality and or contains underground tank condensation water. Fuel stations are supposed to syphon that out periodically, but do they?

Or could just be slight clogging of a nozzle or two. Unscrew all 6 nozzles and stick them in an ultrasonic cleaner bath for a few hours. That will restore them back to good health.

This is why I only use premium diesel in mine. It's had Shell V Power diesel almost it's entire life and runs like a champ. I don't usually buy into over hyped premium fuels, but in my experience, the top Shell stuff does seem to work.

Sounds like your engine is rebuildable Marcel. Nothing seriously out of whack there. Did you measure rod no.5 for straightness to make sure it didn't bend slightly following it's intimate meeting with the head? Might also be worth checking piston 5 didn't suffer ring land cracking as hypereutectic pistons don't especially enjoy physical contact. I would replace the oil pump as well, personally.

Keep us posted chaps. Any clues of a potential cause for the unhappiness during your strip downs?


carl0s

Original Poster:

549 posts

231 months

Saturday 29th June
quotequote all
rottenegg said:
Keep us posted chaps. Any clues of a potential cause for the unhappiness during your strip downs?
I think my main clue was jellified congealed oil yikes

BlueMR2

8,672 posts

205 months

Sunday 30th June
quotequote all
carl0s said:
rottenegg said:
Keep us posted chaps. Any clues of a potential cause for the unhappiness during your strip downs?
I think my main clue was jellified congealed oil yikes
At the end of the video the dash did seem to state it was 2 years late for a service.

However considering you are happy pulling an engine to bits, I'd imagine you would do the oil yourself but perhaps not be able to update the computer.

carl0s

Original Poster:

549 posts

231 months

Monday 1st July
quotequote all
BlueMR2 said:
At the end of the video the dash did seem to state it was 2 years late for a service.

However considering you are happy pulling an engine to bits, I'd imagine you would do the oil yourself but perhaps not be able to update the computer.
It's my girlfriend's car and she definitely missed the last service, and the one before that was a 'we pick it up and return it to you all done' and I have my doubts what they did..

Historically she didn't seem too eager for me to mess with her pride and joy but I think we're beyond that now. I did keep telling her that she really ought to get her service booked in but it fell on deaf ears rolleyes

marcelN57

16 posts

3 months

Monday 1st July
quotequote all
Good to hear your block is fine as well, Carlos! Interesting to see the different damage pattern.

Update from my end:
I've put it all back together, and it's running! bounce

Drove it for a long 700 mile trip this weekend, and it seems to be all good. biglaugh

Video of it running again the first time:



Some photos from the assembly process:

Parts arrived!

OEM crankshaft ($1800 incl. shipping, arrived in about a week)


Measuring block and crankshaft



Inspecting cylinder walls


Yes rottenegg, I did take the injectors apart and cleaned them. I didn't have ultrasonic cleaner so tried to cook them in degreaser in the microwave, which seemed to work reasonably well:


My workspace


Engine "lift". Given circumstances, I put the block in from below and then added head, pan etc in the car.


"First" 699 miles



It was a lot of work. I don't know how many hours, probably more than 100. Doing it in the space that I had (parking garage) added considerable time as the scene always had to look reasonable and limited what types of tools etc I could use.
I had the front wheels just sitting in the front wheel well, not attached to anything rofl, which helped tremendously with optics - it pretty much just looked like a normal parked car for 2months.

There are still two remaining issues now:
1. First time I drove it, it had a weird vibration under load. After a bit of research, concluded that it's most likely coming from the front CV axles. I pulled out fuse #63 ("transmission VTG") which apparently effectively makes it a RWD car. This triggers a warning "vehicle stabliziation malfunction, drive moderately" but works great and vibrations are completely gone
--> I assume I damaged the right CV axle when I pulled it out and tied it away to the side. It seemed to be in an awkward shape when I put it back in. Probably anyway kind of worn after 135k miles, so I ordered both axles and wheel bearings and will renew all of that.
2. It is overheating under high loads. It's about 35-40°C here in Utah right now, and there are a lot of rather steep canyons. Going up Parleys Canyon which is 3000ft / 1km incline over a few miles at about 70mph, it is getting very hot, about 105°C. I stopped and let it cool down before any warning appeared. I was initially shocked and feared a head gasket / EGR cooler / similar issue (I had a cracked head AND both EGR coolers broken last year on this doomed car...).
However there is no coolant loss, nor pressure build in the cooling system. So I assume it could be radiator, thermostat, or water pump. To diagnose this further, I glued a temperature probe on the outlet side of the radiator. That is also getting very hot, within 10°C of the temp that the ECU measures. That's why I assume it's the radiator. I ordered an IR camera and will take a look tomorrow if there is a weird heat pattern on the radiator (I suspect some of the microchannels are clogged).

Good luck with yours Carlos! Great sign that the block is good. I'm sure your girlfriend will learn a lesson!


marcelN57

16 posts

3 months

Monday 1st July
quotequote all
One comment to the first video - the gauge visible in the vid measures oil pressure. I added (via a T at the oil pressure switch port) it to have some good visibility in what is going in, in particular bc I decided to reuse the oil pump.
It started at about 60psi and then dropped down to about 18psi as the engine warmed up. Oil is Shell Rotella T6 5W40

carl0s

Original Poster:

549 posts

231 months

Monday 1st July
quotequote all
That is some impressive work Marcel. I can't believe how clean everything looks.

The vibration thing, it's not like a thud-thud-thud in the back while accelerating is it? We had that on this X4. It was hard to tell that it wasn't just bumps in the road at first, but I thought something was wrong, and it gradually got worse. I realised it was probably the transfer case, and I went down the rabbit hole of measuring overall wheel/tyre diameters, and pricing up new/refurb transfer cases. In the end I did an oil change on the transfer case. I put in some Ravenol TF-0870, and it solved it. I suppose your issue might only be this if you happen to have lost some fluid during the strip down, otherwise as you say it's probably front axles.

My mum's Golf had a bad CV joint and I made the mistake of replacing both sides with non-OEM Chinese driveshafts, and then when I put it back together and went for a drive, the car had a vibration at 3,700rpm, (which I didn't know hadn't been there before because all I could hear before was a clacking CV joint!).

I ended up changing out the clutch and flywheel (DMF), and an engine mount I think, only to later realise that one of the Chinese driveshafts was junk - they used the same solid tube on both sides whereas OEM is hollow and wider diameter on the longer side ( https://www.mig-welding.co.uk/forum/threads/cv-joi... )

Hope your new driveshafts are good quality :-)

marcelN57

16 posts

3 months

Monday 1st July
quotequote all
Thanks Carlos!

I used this degreaser diluted about 50:50, a brush and a pump sprayer to clean most of the parts. Took some time but worked pretty good!

Interesting with the transfer case noise. It's coming from the front in my case, and of the front drive parts, the CV axles are the ones that had to suffer the most / any abuse in this project because they were constantly in the way, so I assume it's them.
I ordered these from GKN - made in Spain and supposedly OE quality. Let's see!

carl0s

Original Poster:

549 posts

231 months

Monday 1st July
quotequote all
marcelN57 said:
Thanks Carlos!

I used this degreaser diluted about 50:50, a brush and a pump sprayer to clean most of the parts. Took some time but worked pretty good!

Interesting with the transfer case noise. It's coming from the front in my case, and of the front drive parts, the CV axles are the ones that had to suffer the most / any abuse in this project because they were constantly in the way, so I assume it's them.
I ordered these from GKN - made in Spain and supposedly OE quality. Let's see!
Thanks very much for the degreaser tips.

Oh yes those are top notch driveshafts. You are into a few dollars here for sure :-)

marcelN57

16 posts

3 months

Monday 1st July
quotequote all
Well I can't stop now, can I?

Good thing is that next to taking up all my money, this is also taking up all my spare time so at least I'm not spending on anything else wink

rottenegg

605 posts

66 months

Friday 5th July
quotequote all
carl0s said:
rottenegg said:
Keep us posted chaps. Any clues of a potential cause for the unhappiness during your strip downs?
I think my main clue was jellified congealed oil yikes
Yeah that would do it biglaugh

Marcel - good work! The motor sounds sweet and those bores look amazing for the mileage. Piston crowns look decent too. That starfish pattern indicates the injector nozzles weren't clogged after all, which again is great for the mileage. The N57 gets a lot of bad press but yours is proof the block is very stout and long lasting. Doesn't seem to be any evidence of ovalizing or excessive wear on the thrust side.

Weird about the coolant temps. I take it all the air got bled out OK? BMWs can be quite picky about that. Did you replace the water pump and thermostat?

marcelN57

16 posts

3 months

Saturday 6th July
quotequote all
Thanks!

Regarding the overheating - I checked the radiator with an infrared camera while the engine was hot and idling (fan was cycling on and off, ECU measured coolant temp was between 98°C and 102°C - the fan cycles on at 102°C)




TL;DR: All looking good. Entire radiator seems to be hot, no cold spots visible. So for me this means coolant pump, thermostat and radiator are all fine. I've driven it now 1000miles, so can't believe there would be any trapped air left. Coolant level in reservoir is constant.

I assume it must be normal like this then. Maybe at these high load / high temperature situations, the coolant temps regularly get >=105C until the fan kicks into high gear?