S54 rod bearing

[Vanne]

Thanks for posting that vid 6, sounds/looks like you were having an awesome day before that.

[ZAR4MC]

Had my Bearings changed out last week at 100 000km's. There was alot of wear on them, glad i managed to get it done before it wore down enough to damage the crank. I've lots of people tell me that you dont have to worry about bearings on these motors and then a small select few who actually knew about the issue and told me to get it done ASAP. glad i listened to them.

[tomscott]

Still an advocate of premature maintenance. Regardless I would have mine done at 80-90k just for piece of mind at the same time you can have a couple of other things done like engine mounts etc and be in for less than £1500 money well spent if you ask me. Worth it rather than loose an engine or an expensive rebuild.

[FD3S]

I am in the phase that my mechanic suggests that we should change the rod bearings. The car is around 90.000 km. I was skeptical about that until I read this topic and I will change them within the month. However I have the following questions for this subject:

Where can you find those rod bearings for sale on the internet?
There are some after market bearings that worths upgrading to?
Also some friends say that since that is a complicated job you need it done by an expert. Is there any way that you can verify that you mechanic is suitable for this job? Any other advice for someone that will change them?

Still an advocate of premature maintenance. Regardless I would have mine done at 80-90k just for piece of mind at the same time you can have a couple of other things done like engine mounts etc and be in for less than £1500 money well spent if you ask me. Worth it rather than loose an engine or an expensive rebuild.

What else do you think worths changing if you buy new rod bearings?

[TomK]

Where can you find those rod bearings for sale on the internet?
There are some after market bearings that worths upgrading to?

They are really only available from BMW. I believe there are some coated after market options but as I understand it the jury is out as to whether they are actually better or not.

Also some friends say that since that is a complicated job you need it done by an expert. Is there any way that you can verify that you mechanic is suitable for this job? Any other advice for someone that will change them?

I think I would want to use someone who has worked on the S54 before however I don't think it is the most complex job in the world.

What else do you think worths changing if you buy new rod bearings?

I was advised to upgrade the rod bolts to ARP items (https://www.turnermotorsport.com/p-2206 ... -m10-size/). You'll need new ones either way.
You might want to consider doing the head gasket and inspection of the cams/followers whilst you're there, but obviously that's not really related to the rod bearing work.

[tomscott]

You have to be careful which bearings you buy there are a few different aftermarket items that have mixed reviews.

TBH I dont know which ones to go for ive heard coated ones can cause tolerance problems and even more oil starvation problems. TBH the BMW items aren't flawed its an engine with small tolerances and a wearable item so I would probably just replace them with oem as at 80-90k (miles) probably will out do your ownership.

I would have the engine mounts replaced as these are rubber and its age that kills them, also one of them is right next to a heat shield and it tends to perish quicker. I would also have the bolts replaced as some tend to work loose and shear. Other than that its up to you I would probably have a compression test to see how the cylinders are doing and if your going the whole hog have it looked at for bore scoring.

But tbh the above is all I would do, good preventative maintenance.

[ga41]

I agree with both tomscott's and TomK's, suggestions. Keep in mind though that in cases of high-mileage engines there might be a need to fit oversized rod bearings because the crank might be worn. We had to do that to my rebuilt engine. My mechanic sourced all the required parts.

We also found on my car that my head gasket (φλάντζα κυλινδροκεφαλής) was on the verge of failing. The gasket is 2 thin sheets of metal with rubber in between them, the metal was fine but at the thin point between two cylinders the rubber layer between the metal sheet was a bit torn...

[GuidoK]

Keep in mind though that in cases of high-mileage engines there might be a need to fit oversized rod bearings because the crank might be worn. We had to do that to my rebuilt engine. My mechanic sourced all the required parts.

You can only fit oversized bearings if you grind the crank (for example if its worn/damaged).
Shells come in 2 sizes, oversize is +.25mm.

Radial rodbearing play should be plastigauged between 0,030mm and 0,070mm and maybe use a micrometer to check roundness.

Also some friends say that since that is a complicated job you need it done by an expert. Is there any way that you can verify that you mechanic is suitable for this job? Any other advice for someone that will change them?

In theory any good mechanic should be able to do this. But usually indies who work on old cars wont have any plastigage or micrometers lying around. But all specs are in the TIS manual, so its doable.....if you have a good mechanic.

Grinding a crankshaft obvously is work for a specialized machine shop, but I doubt that has to be done to your engine (measuring the bearing play should point that out).

[ga41]

Keep in mind though that in cases of high-mileage engines there might be a need to fit oversized rod bearings because the crank might be worn. We had to do that to my rebuilt engine. My mechanic sourced all the required parts.

You can only fit oversized bearings if you grind the crank (for example if its worn/damaged).
Shells come in 2 sizes, oversize is +.25mm.

Radial rodbearing play should be plastigauged between 0,030mm and 0,070mm and maybe use a micrometer to check roundness.

Also some friends say that since that is a complicated job you need it done by an expert. Is there any way that you can verify that you mechanic is suitable for this job? Any other advice for someone that will change them?

In theory any good mechanic should be able to do this. But usually indies who work on old cars wont have any plastigage or micrometers lying around. But all specs are in the TIS manual, so its doable.....if you have a good mechanic.

Grinding a crankshaft obvously is work for a specialized machine shop, but I doubt that has to be done to your engine (measuring the bearing play should point that out).

My original crank was apparently not able to be salvaged, we had a machine shop measure and try but they could not. The crank i ended up using was from a used E46 M3, it was measured and my mechanic decided to install the oversized bearings... That's what I remember anyway, it was 3 years ago! If you want more details I can ask them!

[GuidoK]

Ok, but if you installed oversized bearings, that crank had already been grinded down to that spec.
It's not possible to have wear reduce the crank by that much, or that wear reduces the crankshaft at all so that other size bearings are fitted.
My point is, when wear on the crankshaft results in too much rodbearing play, it always has to be grinded down or replaced.

[ga41]

Ok, but if you installed oversized bearings, that crank had already been grinded down to that spec.

It might very well have been. I don't know for sure.

[FD3S]

Guys thank you so much for the help. So as I understand what I have to order is:
1) Rod bolts (I already ordered today and it was good timing, since I have already given an order to Turner Motorsport for an OEM Alarm during Friday).
2) Stock rod bearings are the safe solution as I understand.
3) Engine mounts. https://www.turnermotorsport.com/p-2157 ... -m-e36e46/
Is this part correct? And how many of them do I need?
4) Inspection of the head gasket.

I wish I had the money for new cams also.

Ga thanks for the translation. I can imagine the face of mechanic telling him that I want rod bearing replacement and a head gasket inspection in English.

[TomK]

Sounds about right.

Many people use this slightly uprated engine mount, it helps with full bore 1st-2nd or 3rd-2nd gear changes I found.
http://www.vibra-technics.co.uk/bmw/z4_ ... gines_only

Otherwise the stock mount you have chosen is the correct part. You'll need 2 of them as with the vibra-technics.
To be honest I would inspect them first, they may still be in good condition, mine were when I replaced them recently. No real point to replace them with stock items if they are still ok and it is not a big job to replace them separately further down the road.

Good luck!

[sixspeed]

Yeah that video doesn't make easy watching. It also shows just how little (no!) warning you get of failure.

I recommend the vibratechnics mounts. Run.full race mounts on my Z and honestly, the increased NVH is negligible, but it improves the feel of the drivetrain no end.

[craig3.2]

Yeah that video doesn't make easy watching. It also shows just how little (no!) warning you get of failure.

I recommend the vibratechnics mounts. Run.full race mounts on my Z and honestly, the increased NVH is negligible, but it improves the feel of the drivetrain no end.

Hey,been a wee while since we have seen a sixspeed post,welcome back.
How is your lovely coupe these days?