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08-31-2004, 05:14 AM
anic's post earlier. It got little play but in his opinion the real problem lies in con rod distortion under high stress.He feels this causes the bearings to lose their gap and bind.(my words here) As con rod replacement would be very expensive, he sees the bearing thing to be a stop gap measure aimed at getting more engines thru warranty period but not really solving the problem. Seeing as how BMW has apparently been trying diff con rod configurations this has the ring of truth to it.

08-31-2004, 12:37 PM
up the same issue. Once again, this is a typical rod big end failure mode. There is a lot of metallurgy behind what is going on, but basically the rods are elongating at high RPM's and reducing the bearing/journal clearance to the point of forcing the oil layer out of the bearing, causing metal to metal contact, and as BMW says "overheating" the bearings.

BMW is trying everything short of replacing the con rods (the needed repair IMHO) to address it. Back in 01 BMW first sent out a SIB (11 08 01) regarding bearing clearance changes (+.01mm). Then we have the first Service Action, now the second S.A. Whoever heard of different upper and lower rod bearing shells on a production engine? Iím guessing this is a tapered clearance bearing, talk about Band-aid repairs! Also mid year change in rod bolt diameter(-1mm) to try to add some material to the shoulder portion of rods, all in an effort to reduce the distortion and keep the rod big end more concentric at high RPMís.

It just pisses me off that BMW went light duty on one of the most critical components on the engine. This design should be good for 9000+ RPM if they had the right rods in it.

08-31-2004, 01:45 PM
is feeling that my motor, which I have meticulously overmaintained, is not really right.

08-31-2004, 01:46 PM
in the 4.8 liter N62 engine in the X5 then? Is it also high rpms?


08-31-2004, 02:01 PM
doing engine work that the fixes BMW has proposed for the S54 bearing issues are related to distortion of the rod big end. That IMHO is the root cause.

The N62 could be the same problem or completely unrelated. If the engines not turning over 7,000 RPM I doubt it's the same problem. What are the details of those failures?

08-31-2004, 02:05 PM
tion and allow some REAL after-market upgrades for "potentially" the best six cylinder on the market. This would allow us (who can afford it..) to build some really wicked M3's.

08-31-2004, 02:27 PM
by getting a 10/02 build car I was safe. I don't like the S.A. one bit. I donít have any confidence in the dealership mechanics doing the first or the second S.A. as meticulous as it needs to be done.

Go read the service action. Besides having to do a field engine repair in a dealership under the time constraints of getting paid BMW ďbook timeĒ, the tech has to; insure that he keeps every part of the repair scrupulously clean, as not to introduce contaminants into the engine, not nick the crank journals or bend the piston squirters when he moves the pistons in the bores to remove and replace the bearing shells, make certain that the blue bearing shells go in the rod and the red bearing shells go in the cap, make certain that the 11mm bolts are replaced in the correct intake or exhaust orientation or that the 10 mm stretch bolts are not reused.

The rod bolts need to be torqued correctly (the 11 mm bolts in my engine will need this done in 3 stages!, go read the S.A.) insuring that the final stage is angle torqued EXACTLY as specified (this is very difficult to do in chassis), and the put the whole mess back together without just slamming it back together with the impact gun (make sure the thrust plate is torqued back in with new bolts in 3 stages) and hoping nothing leaks, squeaks or falls off.

Iím not slamming the techs; Iím simply stating my doubts in the system.

08-31-2004, 02:27 PM
"premature wear of the connecting rod bearings" but we don't know the real cause here. I wonder if it still can be bad bearings from the supplier. Or some other issue during assembly (wrong torque for the conrod bolts)?


08-31-2004, 02:39 PM
guys to replace my doorseals, but I don't really trust them to rebuild my engine.

Building engines just isn't what they do.

<font color=#999999> <b>2002 titanium silver m3 coupe</b> <font color=#99CCFF> <b>2004 world rally blue wrx wagon</b> <font color=#CCCCCC>marina del rey, ca

08-31-2004, 02:56 PM

- Bill

<a href=""><img src="" height=148 width=118 border=0 alt="6sp jb/imola coupe, GC coilovers/sways, Brembos, RAC Monolite RG4s+PS2s, Eisenmann, UUC SSK, Bluetooth and more"></a>

08-31-2004, 03:27 PM
looks like. "Premature wear" is about as accurate as the "overheating bearings" issue in the S54 engine. Like someone else said, it is very rare indeed for a bearing supplier to send out a batch of bad bearings.

Bearings are pretty simple and unless the material is defective, the process of manufacture is pretty basic. I think BMW is fading the heat on this stuff by blaming the bearing vendor. Pretty standard in the industry. The people inside know how to read this as what it really is and the bearing supplier won't loose any business, which had BMW admitted that they designed or built an engine with problems, would not be the case.

I will offer that usually this type of failure is more the result of incorrect assembly or machining and not a poorly designed part as it the case of the S54 con rods. Once again, I've read nothing about this particular failure.

08-31-2004, 04:43 PM
... in order to have a meeting with the manager and the tech, and inquire about how they intend to follow the procedures (how to keep things clean, how they keep the rod bolts in the right order, do they lubricate the bolts, do they torque them in stages, do they take care around the piston squirters)...

I wouldn't be surprised if there is a tech that does care about all these things, so at least if you can interview him and the SM beforehand you can see if you want to have the service done there or go elsewhere.

I would also want to be there at the time the work is being done, at least to see the bearing races to inspect them myself for damage, and take pictures. So I would ask them to let me do that as well.
<HR width=512><B>CBsaksiri</b> Sunnyvale, CA
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