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

[OM VT3]

Originally Posted by Hujan

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.

Clearances

[Rupes]

Originally Posted by leigh

Clearances

Fair enough, but then why perfect a example here after 39k miles using bearings with tighter clearances?

I get the sense that you have some thoughts of your own on this matter, but are making us pull it out of you one post at a time. What is your explanation?

[JEllis]

I have read through this guide a few times. Its the Clevite guide to bearing wear. The guide covers most causes to excessive bearing wear. Page 7 and 8 cover bearing crush.

http://www.remotech.info/uploads/cle..._tech_info.pdf

[BobS]

If the design was flawed you wouldn't have motors going 100-150k with oil change intervals at 15k.

High mileage thread: http://www.m3post.com/forums/showthr...ileage&page=30

I still think its a issue that involves some s65's but not all.

[OM VT3]

Simple.....Because if excessive bearing wear is caused by assembly errors you don't believe bmw screw up 99% of all the s65 engines they build do you?

And yes tolerance stack up explains why some engines last a long time and others fail.

[Shredicus]

Originally Posted by leigh

Simple.....Because if excessive bearing wear is caused by assembly errors you don't believe bmw screw up 99% of all the s65 engines they build do you?

And yes tolerance stack up explains why some engines last a long time and others fail.

So you are concluding that 99% of s65 motors are suffering from excessive bearing wear? And this is corroborated by the observed tolerance analyses?

[OM VT3]

Originally Posted by Shredicus

So you are concluding that 99% of s65 motors are suffering from excessive bearing wear? And this is corroborated by the observed tolerance analyses?

Yes and every single motor that's had bearings taken out have wear

[JEllis]

Here is the Harrop add. On the left are the OE bearings... on the right are the VAC bearings after testing. Considering the 7 micron thickness of the VAC coating... this is impressive. The VAC bearings look very good.

1960847_10152336148908169_1815493102_o by JMEllis, on Flickr

[Rupes]

how come they don't say how many miles are on the new VAC bearings? Seems like that would be critical in comparing them to the OEM ones.

[Killerfish2012]

Originally Posted by JEllis

I have read through this guide a few times. Its the Clevite guide to bearing wear. The guide covers most causes to excessive bearing wear. Page 7 and 8 cover bearing crush.

http://www.remotech.info/uploads/cle..._tech_info.pdf

Since trapped dirt seems to be the most common cause of bearing wear, one cannot stress enough the importance of motor flushing, especially in vehicles that had extended oil drain intervals.

[Killerfish2012]

Originally Posted by Malek@MRF

May we have some pictures of the bottom of these treated bearings, as it would appear that they have significant wear, with the coatings all but eaten away?

[Killerfish2012]

Originally Posted by JEllis

Here is the Harrop add. On the left are the OE bearings... on the right are the VAC bearings after testing. Considering the 7 micron thickness of the VAC coating... this is impressive. The VAC bearings look very good.

Take a closer look at the underside of those treated bearings. Looks like wear to me. Why isn't the underside treated?

[OM VT3]

Originally Posted by Killerfish2012

Take a closer look at the underside of those treated bearings. Looks like wear to me. Why isn't the underside treated?

I don't think the under side really matters

[JEllis]

Originally Posted by Killerfish2012

Take a closer look at the underside of those treated bearings. Looks like wear to me. Why isn't the underside treated?

There not coated on the back.

vacs65rb1-1 by JMEllis, on Flickr

[Killerfish2012]

Originally Posted by leigh

I don't think the under side really matters

Yes, it does, according to the guide. Plenty of pictures of the underside, as it is also used to diagnose bearing issues. See page 9:

http://www.remotech.info/uploads/cle..._tech_info.pdf

[Killerfish2012]

Originally Posted by JEllis

There not coated on the back.

vacs65rb1-1 by JMEllis, on Flickr

Shouldn't they be? In case of trapped dirt or metal particles trapped underneath it.

[JEllis]

Originally Posted by Killerfish2012

Shouldn't they be? In case of trapped dirt or metal particles trapped underneath it.

I don't know to be honest.

[avusm3]

Originally Posted by Hujan

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.

Right on the money...

[LSx]

Originally Posted by Killerfish2012

Shouldn't they be? In case of trapped dirt or metal particles trapped underneath it.

No, you don't want a DFL coating on the back of a bearing shell.

The bearing stays stationary in the rod housing bore(HAS to stay stationary), and if assembled correctly with strict attention to cleanliness, there shouldn't be contaminants trapped behind the shell - that causes wear on the inside where it distorts the bearing.

In some applications we use a doweled rod and bearing in order to help discourage the bearing from spinning in cases where the crush and radial pressure might not be enough - mainly aluminum rod drag race applications...a slick coating on the outside of the bearing shell would definitely not help in this regard.

[Malek@MRF]

I hope everyone had a great New Year with family and loved ones. My apologies I did not get a chance to respond yesterday.

Originally Posted by leigh

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.........

A theory is merely what it is, a theory. It is not a matter of fact. It is an attempt to explain a specific phenomenon, which is what some of us have been trying to do. I am just looking at this from a different angle, in no way am I implying that what regular_guy (PencilGeek), BMRLVR or Kawasaki saying is wrong. These guys knows their stuff better than most. Compiling all the knowledge together will put us on the path of a real solution.

Originally Posted by leigh

These motors are put together by hand

No, they are not unfortunately. While the novelty in knowing our S65's are hand built like the AMG engines, they are not. I have spoken to BMW engineers about this in Munich.

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.

There is no definitive data here. We don't know the treatment of the engine. We don't know the following information which is critical: engine assembler/builder, oil type, boosted/NA.

Originally Posted by Hujan

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.

Occam's razor says #3 based on the options given. Again, I want to be clear, this does not dismiss #1 or #2. #3 is simple, and likely, considering the connecting rod bolt is one of the most important fasteners in the engine. Within the next few days when I reassemble this engine with its VAC bearings and OE rods back onto the same crankshaft, spec the clearances with calibrated instruments in a climate controlled environment, and then break down, and reassemble with OE rod bearings and OE rod bolts, that data should give us all some more concrete information from which we can move forward from. If nothing comes from this from TWO separate engines, then we can look more deeply into #1 as there would be almost no way to verify #2.

Originally Posted by Killerfish2012

May we have some pictures of the bottom of these treated bearings, as it would appear that they have significant wear, with the coatings all but eaten away?

Originally Posted by Killerfish2012

Take a closer look at the underside of those treated bearings. Looks like wear to me. Why isn't the underside treated?

The underside of the coated bearings are normal. They are not coated there, and the marks and stains you see are normal.

Originally Posted by leigh

I don't think the under side really matters

The underside of the bearing actually does matter and provides information on the sizing and assembly of the rod. If the bolts are under-torqued or the bearings do not provide enough crush, the bearing has room to move back and forth within the connecting rod housing. If loose enough, it will spin.

Without enough radial pressure due to insufficient crush, the bearing will also dissipate heat inefficiently, heat up the oil excessively and begin to wear prematurely. Heat will kill a bearing.

I will throw this in to be considered. The OEM bearings and WPC bearings are NOT treated at the part line surfaces, the VAC/Calico coated bearings are. That added thickness at that part of the bearing (given fastener torque specs are correctly followed), will yield to added crush. The wear patterns of the S65's that have been taken apart show bearing wear at the top and bottom halves of the shells, not at the parting lines. As explained before, wear at parting lines dictates excessive crush and bulges the sides of the bearings and wear at the top and bottom halves dictate either oil starvation or lack of bearing crush.

The back side should not be coated, ever.

Originally Posted by JEllis

There not coated on the back.

Correct, they are not and should never be.

Originally Posted by LSx

No, you don't want a DFL coating on the back of a bearing shell.

The bearing stays stationary in the rod housing bore(HAS to stay stationary), and if assembled correctly with strict attention to cleanliness, there shouldn't be contaminants trapped behind the shell - that causes wear on the inside where it distorts the bearing.

In some applications we use a doweled rod and bearing in order to help discourage the bearing from spinning in cases where the crush and radial pressure might not be enough - mainly aluminum rod drag race applications...a slick coating on the outside of the bearing shell would definitely not help in this regard.

Thanks for posting this, your information and knowledge is appreciated.

[Dave07997S]

Originally Posted by JEllis

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?

I find it extremely interesting. In fact it made me feel that the issue is a way the OEM bolts are torqued down more than a clearance issue. Its probably a combination of factors like a airline crash. Its not just one factor.

Dave

[JEllis]

Originally Posted by Dave07997S

I find it extremely interesting. In fact it made me feel that the issue is a way the OEM bolts are torqued down more than a clearance issue. Its probably a combination of factors like a airline crash. Its not just one factor.

Dave

Interesting you mentioned airline crash. I was thinking the same thing. In the aviator world we use the analogy of swiss cheese. Normally the holes don't all line up. Something like an out of spec torque wrench, for example, is caught at the QA level. But sometimes a few seemingly simple mistakes/holes line up to provide a catastrophic failure.

In this case, if we were to speculate, you could say that BMWs use of tight tolerances, combined with something as simple as an out of calibration torque wrench or a bad batch of bolts, add in less than stellar quality assurance and you have a failure.

Of course, this is just fun speculation and should not be taken as anything more.