MRF Engineering: Rod Bearings, Teardowns, Failures & Replacements. **PICTURE Diary**

[Richbot]

I would bet that almost all S65's exhibit significant bearing wear. Absence of evidence is not evidence of absence. Most internal engine issues are undetectable right up until they're not. The trick is whether or not it actually causes a problem.

[Killerfish2012]

Originally Posted by s85e90

Those looked pretty good

+1.5!

[chris719]

They only look good because the pictures are way too dark. The car has 30k miles, they should look pristine.

[Killerfish2012]

Originally Posted by douglee25

I think what people forget here is that bearings aren't considered a wear item. They never have and never will be. There should be zero wear on those bearings. Of course special purpose cars (ie drag cars) could be a different story. With that said, bearings should last the lifetime of the vehicle. Think 300k+ miles.

Doug

This sentence should have ended with" ", on vehicles that redline at or below 6,500 rpms."

[chris719]

The engine should be designed to operate without self destructing within it's entire rev range. The Audi 8200 RPM 4.2L V8 does not seem to have bearing problems like this engine. The Porsche 3.8L Mezger revs even higher and does not have premature bearing wear either.

[Petros]

Originally Posted by Killerfish2012

This sentence should have ended with" ", on vehicles that redline at or below 6,500 rpms."

That's just the common excuse fanboys make for the M3 bearing issue. The 8400 rpm redline isn't something unique or earth shattering. 8 years before that Honda made the S2000 that can redline at 9200 rpm. And those cars are still running like a horse today without any bearing problems. There are plenty of high revving cars. Yet none of them have bearing issues except those with a roundel on the hood.

[ilikebmxbikes]

Originally Posted by chris719

They only look good because the pictures are way too dark. The car has 30k miles, they should look pristine.

Looking at the new photos the bearings look even better. My car with 27k looked much more worn.

[mj89h]

Originally Posted by ilikebmxbikes

Looking at the new photos the bearings look even better. My car with 27k looked much more worn.

Like I previously stated my motor turned out to be very healthy... but there was no way of truly knowing unless this was done...even with a clean oil analysis report.

After witnessing Malek's engine give way at streets of willow I concluded i'd rather pay 2k and have peace of mind than risk 20k and no car for months.

Not to mention I got fresh power steering fluid

[Killerfish2012]

Originally Posted by Petros

That's just the common excuse fanboys make for the M3 bearing issue. The 8400 rpm redline isn't something unique or earth shattering. 8 years before that Honda made the S2000 that can redline at 9200 rpm. And those cars are still running like a horse today without any bearing problems. There are plenty of high revving cars. Yet none of them have bearing issues except those with a roundel on the hood.

Yes the S2000 was exceptional, but the Acura RSX-S bearings would give way now and then. But of course I'll stop before you argue hondata ecu reflash.

[Petros]

Originally Posted by Killerfish2012

Yes the S2000 was exceptional, but the Acura RSX-S bearings would give way now and then. But of course I'll stop before you argue hondata ecu reflash.

I don't know squat about the rsx. what did they determine was the cause of the bearing failure? did anyone measure the clearance?

[Killerfish2012]

Originally Posted by Petros

I don't know squat about the rsx. what did they determine was the cause of the bearing failure? did anyone measure the clearance?

I'm not sure, but back in the day there were a few on the clubrsx forums.

[ilikebmxbikes]

Originally Posted by mj89h

Like I previously stated my motor turned out to be very healthy... but there was no way of truly knowing unless this was done...even with a clean oil analysis report.

After witnessing Malek's engine give way at streets of willow I concluded i'd rather pay 2k and have peace of mind than risk 20k and no car for months.

Not to mention I got fresh power steering fluid

No one questions the value of preventative maintenance and peace of mind. I did mine before the suggested mileage as you did. Mine didnt look terribly by any means and showed signs expected for 30k but yours seriously look great. You should be very happy.

[MilehighM3]

Originally Posted by mj89h

After witnessing Malek's engine give way at streets of willow

Which further proves what? To those that think going away from the 10w-60 and running the car at its limits should think again? With the proper oil in the engine the risk of failure is greatly reduced, especially in extreme conditions. Those who think 0w-40 will fix the problem should think twice.

[chris719]

There have been stock M3's not even tracked that have had engine failure <10k miles. The oil may not be a factor at all, just tolerance stack up.

[mj89h]

Originally Posted by MilehighM3

Which further proves what? To those that think going away from the 10w-60 and running the car at its limits should think again? With the proper oil in the engine the risk of failure is greatly reduced, especially in extreme conditions. Those who think 0w-40 will fix the problem should think twice.

I believe the tolerances play the greatest factor. My motor was particularly loose which could attribute to the condition.

I personally don't think running 0w40 in extreme heat at the track makes sense but for daily driving its ideal. Once the bearings break in I'm going to flush 0w40 and see if there are any tangible differences in overall feel and oil temps.

[thekurgan]

Originally Posted by mj89h

I believe the tolerances play the greatest factor. My motor was particularly loose which could attribute to the condition.

I personally don't think running 0w40 in extreme heat at the track makes sense but for daily driving its ideal. Once the bearings break in I'm going to flush 0w40 and see if there are any tangible differences in overall feel and oil temps.

Who told you your tolerances were loose(r) than norm?

[mj89h]

Originally Posted by thekurgan

Who told you your tolerances were loose(r) than norm?

The guy who replaced my rod bearings

Obviously no formal measurements were taken, just physically observing the amount of play/wiggle room in the rod assembly. If the bearings didn't come out this clean I wouldn't be going on a limb and saying this.

It also might be worth noting that the car drastically opens up when it's reached full operating temperature ~210. Could be a characteristic of a motor with relatively looser tolerances imo

[Petros]

Originally Posted by mj89h

The guy who replaced my rod bearings

Obviously no formal measurements were taken, just physically observing the amount of play/wiggle room in the rod assembly. If the bearings didn't come out this clean I wouldn't be going on a limb and saying this.

It also might be worth noting that the car drastically opens up when it's reached full operating temperature ~210. Could be a characteristic of a motor with relatively looser tolerances imo

we're talking about clearances in the range of a fraction of a millimetre. I'm pretty sure you shouldn't notice a significant wiggle or looseness just with a naked eye.

[mj89h]

Originally Posted by Petros

we're talking about clearances in the range of a fraction of a millimetre. I'm pretty sure you shouldn't notice a significant wiggle or looseness just with a naked eye.

You are correct.... this is totally just my opinion.

Ultimately the condition of the bearings speaks volumes.... my guess on loose tolerances could be one of many reasons why they are in this condition. Id like to also think having a paranoid owner is another reason

[Amirsm3]

Does Malek still have the bearings? He can measure them and report the differences. The data may or may not be significant, but it's not like motors are cheap or time efficient to pull apart and have this kind of data floating around.

[SenorFunkyPants]

Too big a clearance is as bad as too tight.

[Malek@MRF]

Originally Posted by MilehighM3

Which further proves what? To those that think going away from the 10w-60 and running the car at its limits should think again? With the proper oil in the engine the risk of failure is greatly reduced, especially in extreme conditions. Those who think 0w-40 will fix the problem should think twice.

Considering many things, the car ran much better with the Mobil1 0W-40 than it did with the Castrol TWS 10W-60 oil. The engine was less noisy during cold start up, and the noise I am referring to is the noise an engine would make if the bearings are "dry". The oil temps were lower on the street AND at the track with the Mobil1. Lastly, datalogging on street and at HPDE's, the oil pressure remained right where it should for the engine. Mobil1 0W-40 is an excellent oil.

Originally Posted by mj89h

I believe the tolerances play the greatest factor. My motor was particularly loose which could attribute to the condition.

I personally don't think running 0w40 in extreme heat at the track makes sense but for daily driving its ideal. Once the bearings break in I'm going to flush 0w40 and see if there are any tangible differences in overall feel and oil temps.

Many high performance cars, that are more so designed for track duty and spin at even higher RPM's with higher power outputs, higher compression ratios than our beloved S65 M3's run Mobil1 0W-40.

Originally Posted by Amirsm3

Does Malek still have the bearings? He can measure them and report the differences. The data may or may not be significant, but it's not like motors are cheap or time efficient to pull apart and have this kind of data floating around.

I still do have the bearings. Each shell is labeled and placed in their appropriate bags. Labeled as T1/B1 (Top1/Bottom1) and so forth all the way through cylinder number 8. I am not sure what you would like me to measure with a micrometer, but I doubt it will be of any help considering the bearings are already worn, and the crankshaft itself is not here to be measured.

The most staggering things to observe in this particular engines rod bearings is the radial scoring on some of the bearings, and on some bearings pieces of bearing coating have simply chunked off.

Originally Posted by SenorFunkyPants

Too big a clearance is as bad as too tight.

This is true, but the S65 has a long way to go before its clearances are considered too loose.