VAC Coated Rod Bearings, A FULL engine teardown after 39,500 Miles. Look inside!

[OM VT3]

Originally Posted by aussiem3

This information is gem. Thank you very much for posting Malek. So we don't know how many lucky ones with correctly torqued engines are out there.

You're at the mercy of BMW's automated engine build process. Who knows, even a cockroach could have entered an engine during the assembly process.

http://www.m3forum.net/m3forum/showthread.php?t=386602&page=2

Those rod bolts would have be torqued up right and bearings are still no good yes there not vac ones but you seem to think if there torqued up correct there shouldn't be a problem

[aussiem3]

Originally Posted by leigh

http://www.m3forum.net/m3forum/showthread.php?t=386602&page=2

Those rod bolts would have be torqued up right and bearings are still no good yes there not vac ones but you seem to think if there torqued up correct there shouldn't be a problem

[OM VT3]

this is not a sign of rod bolts not been torqued up correct its is a sign of not enough bearing clearance

rod bolts were all torqued propely and are just as good if not better then ARP and bearing are WPC treated and failed with a spun bearing with less then 8000kms

[tdott]

Thank you for your efforts Malek, if you were closer to me you'd be building my engine.

[SilentAttack]

interesting information.

[OM VT3]

Originally Posted by tdott

Thank you for your efforts Malek, if you were closer to me you'd be building my engine.

According to Maleks theory this shouldn't happen

These are standard s65 Carrillo rods with Carrillo M9-CARR rod bolts these are Carrillo rods of exact oem s65 replacements not custom sizes or anything

This engine spun a WPC treated bearing in less that 8000kms these rod bolts were tightened with Carrillo thread lubricant to exact Carrillo specifications

If rod bolts were the problem then this shouldn't have happened but if bearing clearance was the problem then it still could.........

[SenorFunkyPants]

It would be usual on the engine production line for the OEM TTY rod bolts to be fitted by machine in a tightly controlled process. I guess its possible that something could go wrong for a small number of engines but I would have thought it unlikely that incorrectly torqued bolts could to be the cause of high bearing wear in all cases.
Looking at engines that are working perfectly and taking clearances from them makes far more sense than guessing at a new rod bearing clearance, applying it and waiting for a couple of years to see if the engine holds together.
What would also be interesting would be to pull apart some of the high mileage engines (>100,000 miles) that are still running perfectly and see what the rod bearing clearances are in those.

[xpunisherx]

Much appreciated Malek. Your information is an important step in solving the rod bearing issue!

[OM VT3]

Originally Posted by SenorFunkyPants

It would be usual on the engine production line for the OEM TTY rod bolts to be fitted by machine in a tightly controlled process. I guess its possible that something could go wrong for a small number of engines but I would have thought it unlikely that incorrectly torqued bolts could to be the cause of high bearing wear in all cases.
Looking at engines that are working perfectly and taking clearances from them makes far more sense than guessing at a new rod bearing clearance, applying it and waiting for a couple of years to see if the engine holds together.
What would also be interesting would be to pull apart some of the high mileage engines (>100,000 miles) that are still running perfectly and see what the rod bearing clearances are in those.

These motors are put together by hand

[SenorFunkyPants]

Originally Posted by leigh

These motors are put together by hand

Porsche engines are put together by hand but they still use automatic preset tools that fit TTY bolts.

[OM VT3]

Originally Posted by SenorFunkyPants

Porsche engines are put together by hand but they still use automatic preset tools that fit TTY bolts.

Yeah that you turn with your hand

[OM VT3]

I'm guessing this is the tool that they use

http://m.youtube.com/watch?feature=y...&v=EcvD_VaJ2UE

[SenorFunkyPants]

If they made 66,000 engines at that speed they would need forever!...Maybe they do but somehow I doubt it.
EDIT:
I guess they would use something like this:
skip to around 3 mins 30 sec
They even check the side clearance!!

[aussiem3]

Originally Posted by leigh

These motors are put together by hand

That video you're referring to is the assembly of a pre-production engine. I thought the same but was corrected by someone here. Do you see 10 different mechanics assembling engines, No. So if it is just one person doing it, and given the number of ///3s sold, like SFP said, they will still be building.

[avusm3]

This is great information from Malek - thank you for providing this to the E9x community.

The OEM bearing wear seen on the engine he tore down at 6k miles was certainly excessive. The fact that it was rebuilt with the same crank, same rods, with bearings with known reduced clearance, and went another 35k miles with virtually no bearing wear is pretty amazing.

Wear on the original bearings clearly indicate either under torqued rod bolts, excessive bearing clearance (which we all think is highly unlikely with this engine) or rod bolts that were not able to maintain their clamping force on the bearing. If the engine left the factory with under-torqued bolts than one would think that the engine wouldn't last long. If the issue was that the rod bolts were not able to hold their clamping force on the bearing - then this might only be apparent over time - and would be function of the amount of time the engine spent at higher rpms.

With all the evidence we have right now, the lack of/reduction in clamping force over time seems like a very possible cause of the issues with these engines that can take years to manifest.

I'd really love to know why BMW specs the 3x torque procedure on these bolts, when leaders in the field like ARP spec only 1 torque procedure per bolt.

With the BMW technique, if a bolt is taken marginally beyond the yield point on the first torquing, it will go further and further beyond yield with each subsequent torquing, which could potentially result in a bolt that had been taken beyond yield 3 times by the time the full torquing procedure was complete....

The information on the carrillo rods and bolts is interesting, but introduces a lot of new variables into this particular discussion.

[Hujan]

Originally Posted by avusm3

This is great information from Malek - thank you for providing this to the E9x community.

The OEM bearing wear seen on the engine he tore down at 6k miles was certainly excessive. The fact that it was rebuilt with the same crank, same rods, with bearings with known reduced clearance, and went another 35k miles with virtually no bearing wear is pretty amazing.

Wear on the original bearings clearly indicate either under torqued rod bolts, excessive bearing clearance (which we all think is highly unlikely with this engine) or rod bolts that were not able to maintain their clamping force on the bearing. If the engine left the factory with under-torqued bolts than one would think that the engine wouldn't last long. If the issue was that the rod bolts were not able to hold their clamping force on the bearing - then this might only be apparent over time - and would be function of the amount of time the engine spent at higher rpms.

With all the evidence we have right now, the lack of/reduction in clamping force over time seems like a very possible cause of the issues with these engines that can take years to manifest.

I'd really love to know why BMW specs the 3x torque procedure on these bolts, when leaders in the field like ARP spec only 1 torque procedure per bolt.

With the BMW technique, if a bolt is taken marginally beyond the yield point on the first torquing, it will go further and further beyond yield with each subsequent torquing, which could potentially result in a bolt that had been taken beyond yield 3 times by the time the full torquing procedure was complete....

The information on the carrillo rods and bolts is interesting, but introduces a lot of new variables into this particular discussion.

What information? All we've seen is vague, generalized conjecture and hearsay. Ditto for the set of VAC coated bearings that were supposedly shredded in another car.

[avusm3]

Originally Posted by Hujan

What information? All we've seen is vague, generalized conjecture and hearsay. Ditto for the set of VAC coated bearings that were supposedly shredded in another car.

Agreed. The information on the carrillo rods/bolts in the other car are probably not relevant to this discussion on what Malek has uncovered.

[pbonsalb]

Plus, how much extrapolation can you do from one example? Some people seem to think you cannot extrapolate much from 100 examples of failed rid bearings.

[OM VT3]

99% of every motor has shown premature bearing wear

You guys really think they all didn't have rod bolts torqued correctly?

Seems like such a simple fix why didn't bmw do it unless that not really the problem

And btw that thing they torque the bolts down is there to eliminate error not create

[OM VT3]

Originally Posted by avusm3

This is great information from Malek - thank you for providing this to the E9x community.

The OEM bearing wear seen on the engine he tore down at 6k miles was certainly excessive. The fact that it was rebuilt with the same crank, same rods, with bearings with known reduced clearance, and went another 35k miles with virtually no bearing wear is pretty amazing.

Wear on the original bearings clearly indicate either under torqued rod bolts, excessive bearing clearance (which we all think is highly unlikely with this engine) or rod bolts that were not able to maintain their clamping force on the bearing. If the engine left the factory with under-torqued bolts than one would think that the engine wouldn't last long. If the issue was that the rod bolts were not able to hold their clamping force on the bearing - then this might only be apparent over time - and would be function of the amount of time the engine spent at higher rpms.

With all the evidence we have right now, the lack of/reduction in clamping force over time seems like a very possible cause of the issues with these engines that can take years to manifest.

I'd really love to know why BMW specs the 3x torque procedure on these bolts, when leaders in the field like ARP spec only 1 torque procedure per bolt.

With the BMW technique, if a bolt is taken marginally beyond the yield point on the first torquing, it will go further and further beyond yield with each subsequent torquing, which could potentially result in a bolt that had been taken beyond yield 3 times by the time the full torquing procedure was complete....

The information on the carrillo rods and bolts is interesting, but introduces a lot of new variables into this particular discussion.

A bolt can't be taken past its yield point the machine would have 3 setting these things are put in place so something like this doesn't happen

[JEllis]

Originally Posted by leigh

99% of every motor has shown premature bearing wear

You guys really think they all didn't have rod bolts torqued correctly?

Seems like such a simple fix why didn't bmw do it unless that not really the problem

And btw that thing they torque the bolts down is there to eliminate error not create

I think all that anyone is saying here is that its interesting that this motor, with its history and previous bearing install exhibited no wear. Don't you think thats interesting?

[Hujan]

Originally Posted by leigh

99% of every motor has shown premature bearing wear

You guys really think they all didn't have rod bolts torqued correctly?

Seems like such a simple fix why didn't bmw do it unless that not really the problem

And btw that thing they torque the bolts down is there to eliminate error not create

If 99% of the motors have premature wear, then something is clearly wrong. The explanations are either:

1. A fundamental design flaw in the rod/crank clearances by BMW engineers;
   .
2. Sloppy assembly by the lower-paid employees who perform engine assembly; or
   .
3. Bolt hardware that has a tendency to be incorrectly torqued or lose its torque as time goes on

Take 15 minutes and then let us know which you think is most likely.