08 Rod bearing pics

[mambodave]

08, e93, 99000 miles exactly. Just picked the car up and did a preventative replacement all dealer records and no record of it being done. 1 to 8 in order top and bottom.

[Bubbles]

Unbelievable!

An E93 about to break the 100k barrier!



Bearings have seen better days, good call on the swap.

[WAKman]

Good call. Those look kind of unhappy. I did mine when I bought the car and they looked way better than those. I think it's just a must-do on these cars.

[Mpow-wow]

My 08’ just broke 100k! 😱😬😅🤞🏻

[brettcp]

106k on my '12 E93 now. Had bearings done at 94k @ MRF

[Helmsman]

Looks brand. Tad wear on 4th top. Replaced all?

[OldenburgerM3]

What does a failure look like? Worn through?

[pbonsalb]

Failure is bearing that has spun and/or become welded to crank. Many of the picture of removed bearings show some heavily worn bearings or bearings that are failing.

[jiggz]

Originally Posted by OldenburgerM3

What does a failure look like? Worn through?

These are some of the worst I've seen - at least the ones that have chipping. I saw these in person, I had my car at the same shop/same time for RB replacement.

https://www.m3post.com/forums/showthread.php?t=1352151

[akkando]

Originally Posted by pbonsalb

Failure is bearing that has spun and/or become welded to crank. Many of the picture of removed bearings show some heavily worn bearings or bearings that are failing.

My understand is the structural integrity changes as the bearing is worn down. Then it warps enough where the end of one half of the shell gets under the other and spins.

[tdott]

Originally Posted by OldenburgerM3

What does a failure look like? Worn through?

Do you mean sound like?

[Scharbag]

Originally Posted by akkando

My understand is the structural integrity changes as the bearing is worn down. Then it warps enough where the end of one half of the shell gets under the other and spins.

Pretty sure that bearings spin once the hydrodynamic wedge is so badly compromised that mechanical contact occurs. Once that happens, friction makes heat, heat causes galling and blamo, the crank grabs the shell and spins it. The locating tang then ruins the big end of the rod, as well as the crank and, if the rod breaks, then it also ruins the block as it allows the sunshine in...

All of this happens without much warning over a very short period of time.

Good times...

[CSBM5]

Originally Posted by Scharbag

Pretty sure that bearings spin once the hydrodynamic wedge is so badly compromised that mechanical contact occurs. Once that happens, friction makes heat, heat causes galling and blamo, the crank grabs the shell and spins it. The locating tang then ruins the big end of the rod, as well as the crank and, if the rod breaks, then it also ruins the block as it allows the sunshine in...

All of this happens without much warning over a very short period of time.

Good times...

Exactly. The description in the video is totally out in left field with no basis in reality.

[akkando]

Originally Posted by CSBM5

Exactly. The description in the video is totally out in left field with no basis in reality.

Wouldn't the wear marks be from contact on the journal?

[Scharbag]

Originally Posted by akkando

Wouldn't the wear marks be from contact on the journal?

Yes, when the hard crank physically touches the soft Babbitt, wear occurs. Hydrodynamic bearings should not allow metal to metal contact when designed properly. There will be some contact on startup until there is adequate pressure and flow. But the engine is not usually loaded at startup and the rpm is low.

When a bearing is too tight, the hydrodynamic wedge does not properly protect against physical contact when loaded. This damages the Babbitt over time. If it gets bad enough, then there will be too much metal to metal contact and this will cause a bearing to spin due to excess friction. The wear we are talking about is measured in thousandths of inches. And, unfortunately, bearings do not wear evenly and self-clearance.

Hydrodynamic bearings should outlast the chassis of the car. They should not need to be replaced in the normal service life of the vehicle if properly designed. The S65 is a nice engine, but it uses the same rotating assembly fundamentals as everyone else. It is not special. And at ~103 HP/L, it is not pushing the specific output envelope. Yes, it revs pretty high. But so do a lot of other cars.

Cheers,