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      07-26-2016, 05:10 PM   #1
Alex@Redline360
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Is the real problem crank bearings for the S65?

I was speaking with a BMW tech about the S65 rod bearing issue, and he said that the issue is not with the rod bearings. He says the issue is with the crank bearings. What happens is the crank bearings wear, which wears on the crank and causes the crank to damage the rod bearings.

He says this is why some people put in new rod bearings and then experience failure any way.

He says you can generally see oil seeping through the crank seal as a sign.

So wanted to throw this out there as food for thought as I haven't seen this discussed as a theory (though I could have just missed it).

So the question is, has anyone measured their crank bearings or checked their crank bearings when taking apart a motor for rod bearings? Anyone have any info that could potentially prove or dismiss this as a theory?

Would love to hear any theories or see anyone with data as if this is truly the case, I hope this post can lead to some progress in solving the problem.

Edit: Just added two photos.

Photo 1: This photo shows the play in the seal around the crank bearing where the tech says it starts to leak.

Photo 2: Shows how it heated the crank and rod super hot.. See how it's black? Destroyed the bearing in that as well. If it was just the rod bearing that was bad you wouldn't see the crank in this condition or oil coming out of the seal
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      07-26-2016, 05:26 PM   #2
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This seems like it could possibly make some sense bc people have been blowing the motors even after they have done the replacement bearings.. That's why I wanna wait it out a little before I jump the gun..
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      07-26-2016, 06:06 PM   #3
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Hmmmm interesting.... curious also...

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      07-26-2016, 07:19 PM   #4
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Edit: Just added two photos.

Photo 1: This photo shows the play in the seal around the crank bearing where the tech says it starts to leak.

Photo 2: Shows how it heated the crank and rod super hot.. See how it's black? Destroyed the bearing in that as well. If it was just the rod bearing that was bad you wouldn't see the crank all in this condition or oil coming out of the seal
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      07-26-2016, 07:34 PM   #5
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Or...

The rod bearing became worn, causing the engine to knock, which caused damage to the crank bearings. Not sure how to tell which came first...
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      07-26-2016, 08:28 PM   #6
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Interesting...
The play (wear) in the seal around the crank bearings must cause serious vibrations on the crank .
These vibrations on the crank can lead to our bearing wear and bearing failures.
I saw a lot bearings with the "wave pattern wear" and thought it was caused by SC cars .
But now I think I need to change my theory and think that the "wave pattern wear" on the bearings is probably caused by the increased vibrations on the crank ..run hotter ect..
All we have is only theory and pics ...But this "could be" "one" of the main reasons of our Worldwide S65 and S85 bearing problem !
And "maybe" this can be also the cause of the S65 ticking noises .

And if BMW knows about it..What are they waiting for ?
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      07-26-2016, 11:42 PM   #7
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Very interesting. Having recently suffered failure with aftermarket bearings this gives me some things to look for when dissecting my engine.
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      07-27-2016, 12:31 AM   #8
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This seems like a very unlikely scenario. For starters there have been only a small handful of main bearing failures. The rod bearing failures we're talking about at this site, were not accompanied by main bearing fatigue or failure on the ones our shop has seen. If the main bearing is in failure and it already took out one set of rod bearings without seizing itself, then you won't get another 20000 miles out of another set of rod bearings; you won't even get 200 miles out of another set of rod bearings. Once those mains fail and spew debris inside the crank oil galleys, then the next two rod bearings will be destroyed very shortly.

The front oil seal isn't a load bearing member for the crankshaft. If the oil seal fails, then it won't set the engine out of balance. The oil seal failure also doesn't seem cause to the main bearing failure. But a crankshaft in main bearing failure will superheat as you've seen, and cause the front oil seal to melt and fail. So in this case, it looks more like the front oil seal was another victim of the main bearing failure, not the cause of it.

When a main bearing fails, it's very common to take the successive rod bearings out with it. But a rod bearing failure doesn't take the main bearing with it. When a main bearing seizes, it crankshaft won't rotate. When a rod bearing seizes, it pukes shrapnel out the side of the block. The rod bearing failures we're talking about on this forum are the latter and don't coincide with main bearing failures.

Regarding main bearing failure. First I apologize to all you supercharged guys for having to say this. But your supercharger puts extra load on the #1 main bearing. The main bearing failures I've seen have all been on #1 main except two engines. I'm pretty sure all of the #1 main bearing failures I've seen have all been supercharged cars. Whereas the many many more rod bearing failures I've seen have been a mixture of NA and supercharged cars, probably evenly distributed between them.
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      07-27-2016, 12:54 AM   #9
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Interesting theory. I might add that seeping oil from anywhere cannot help matters, so would be good to further explore the seal as a cause of oil loss/starvation. Also wonder whether those with RB or MB failures have experienced higher than average oil loss (meaning they add more oil than normal between changes).
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      07-27-2016, 08:10 AM   #10
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Quote:
Originally Posted by Doc Oc
Very interesting. Having recently suffered failure with aftermarket bearings this gives me some things to look for when dissecting my engine.
What kind of bearings?
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      07-27-2016, 08:31 AM   #11
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No part of that makes sense...sorry.

The leakage that is shown is from the ends of the passages on the bedplate sealant channels. The sealant is injected prior to sealing the ends of the channels to allow air to escape. When sealant extrudes from the channels on both sides at front and rear main seal holes, primer is applied to put the sealant on. Finally, Drei Bond is applied to seal the two chamfered edges on the front of the main seal radius. The leakage in that first picture appears to be from failure of that sealant at the edges.

Now, as for the gap, that looks to me as if the retention bolt for the "intermediate piece" is missing and it's canted down at an angle. I could be wrong, but see the assembly drawing for the here:
http://www.realoem.com/bmw/enUS/show...diagId=11_4118

If bolt (8) is not installed, piece (6) will have play.


Having removed the crank for weld repair and fully rebuilt several S85s, I have never seen any significant amount of bearing wear on main bearings. And yes, all the journals were measured both with and without main bearings installed to verify replacement main bearing sizes as I won't blindly follow the bearing color coding on the bedplate and crank. From the engines I've rebuilt (all from spun rod bearings) , I've never seen any main bearing measure beyond the specifications given in TIS and interpolated color codes.

The most wear I have seen is on the #6 main / thrust bearing only on SMG engines, oddly never on 6MTs. This has me wondering if it's due to bolt-up stresses of the SMG being so long as the engine transmission are supported on opposing ends (nearly) as a single unit. The SMG being longer would mean greater distance between supporting points with higher longitudinal compressive stress on the top of the block and higher longitudinal tensile stress at the bottom of the block. Supposition though, no means or desire to chase it as I've not seen a main fail as a result.

As for the discoloration, the portion which sees the greatest discoloration is the source of the heat. In this case, the rod cap is the darkest, so it seems the rod itself was the source. Given, the crank is larger so it has a higher specific heat capacity, so the smaller rod being darker is a good indication the rod/crank/bearing interface heated the crank, not the other way around.

Finally, agreed with the above, statement of SC vehicles. You are applying a continuous lateral load on a bearing in order to maintain belt tension and prevent belt slippage. It's not surprising to see the bearing taking the brunt of that load wearing.
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      07-27-2016, 09:45 AM   #12
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Sweet! another way for indies to screw ignorant owners. $$$$$$$$$$$$
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      07-27-2016, 10:31 AM   #13
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Quote:
Originally Posted by nyfg56 View Post
What kind of bearings?
VAC. However, I don't believe at this time it was the bearing manufacturer's fault. Will know much more in the next couple weeks but my engine lasted 13k miles after the bearing swap. I'll be putting up a thread on the whole situation soon, but need to know more before I do.
      07-27-2016, 10:42 AM   #14
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Quote:
Originally Posted by Doc Oc
Quote:
Originally Posted by nyfg56 View Post
What kind of bearings?
VAC. However, I don't believe at this time it was the bearing manufacturer's fault. Will know much more in the next couple weeks but my engine lasted 13k miles after the bearing swap. I'll be putting up a thread on the whole situation soon, but need to know more before I do.
I've heard of this happening to a few VAC users now. Been thinking about doing mine and going with BE but am skeptical it will prevent anything now with these replacement bearing failures
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      07-27-2016, 11:00 AM   #15
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We have seen main bearing failures, but I'm going to have see a lot more evidence to believe that load.

I have had BMW techs tell me through the SA that my car needed a walnut blast because it's direct injected. I have had to show techs the diag procedure for battery testing to get them to come to the right result. Think about that for a minute. Your friend may be a genius master mechanic extraordinaire, but I don't find "a BMW tech said so" to be all that persuasive a source without more info.
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      07-27-2016, 11:02 AM   #16
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Quote:
Originally Posted by nyfg56 View Post
I've heard of this happening to a few VAC users now. Been thinking about doing mine and going with BE but am skeptical it will prevent anything now with these replacement bearing failures
I haven't heard of any others....can you point me in the right direction?
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      07-27-2016, 11:02 AM   #17
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Quote:
Originally Posted by Doc Oc
Quote:
Originally Posted by nyfg56 View Post
I've heard of this happening to a few VAC users now. Been thinking about doing mine and going with BE but am skeptical it will prevent anything now with these replacement bearing failures
I haven't heard of any others....can you point me in the right direction?
On this forum I believe in the s65 blown engine thread
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      07-27-2016, 11:07 AM   #18
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Thanks I'll look. My engine was brought up in that thread too I think....didn't want my name mentioned at the time though....
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      07-27-2016, 11:41 AM   #19
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Also note in the second photo that the only portion of the crank which is discolored is the outer edge by the rod journals. Not further down the web. I would guess this is due to the thinner material on the end being easier to heat as a result of less cooling from the oil passages leading from the main journals down through the web to the rod journal. Another clear indication the heat was generated at the rod journal and not conducted from the non-discolored portion closer to the main journal.

Concur with BMW techs. Saw a car in for engine replacement in MI that had been previously attempted by a dealership. Every single part had a number written on it paint pen in the order it was taken off so they could assemble by numbers on the way back in. Highly proficient. Also, they installed the two longer transmission bolts which are supposed to be at the top of the engine block into the two lowest holes...the ones in the oil pan. Oddly, the oil pan was punctured in two places and leaking out of the transmission bolt holes. Solution? Add crush washers to seal it...
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      07-27-2016, 01:47 PM   #20
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Quote:
Originally Posted by nyfg56 View Post
On this forum I believe in the s65 blown engine thread
My 2nd set of WPC bearings spun at 27k on them, so very possible its not just the VAC bearings but simply that swapping bearings does not buy as much time as we had hoped.
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      07-27-2016, 02:24 PM   #21
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Quote:
Originally Posted by squartus
Quote:
Originally Posted by nyfg56 View Post
On this forum I believe in the s65 blown engine thread
My 2nd set of WPC bearings spun at 27k on them, so very possible its not just the VAC bearings but simply that swapping bearings does not buy as much time as we had hoped.
Thank you^ this is what worries me about spending $2,500 to swap them lol
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      07-27-2016, 11:35 PM   #22
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Thank you^ this is what worries me about spending $2,500 to swap them lol
That guy is supercharged. There's a difference but that is still alarming.
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