///M Rod Bearings, Vanos Bolts & Motor Mounts

[original guvnor]

Apologies I probably wasn't very clear when I was talking about the warranty covering bearing shell wear. I meant if they failed rather than carrying out preventative maintenance.

Interesting thread this

 

[StevenH72]

Very interesting thread. As Tom said, you have to be an S54 geek to maintain properly. This thread is certainly helping

 

[Shipkiller]

This was written around the time the S54 Bearing issue was in full swing. Interesting read:

http://www.shipkiller.com/StoneWalk_s_S54_Failure_History.html

 

[BMWZ4MC]

This was written around the time the S54 Bearing issue was in full swing. Interesting read:

http://www.shipkiller.com/StoneWalk_s_S54_Failure_History.html

Very interesting read. Has anyone heard of bearing shell failure affecting a Z4M or are there just reports of wear when inspected as a proactive maintenance step? Incidentally, mine were inspected at 50,000 miles (mostly enthusiastic road use but also quite a few trackdays) and they weren't worn excessively or showing any evidence of oil starvation, but it seemed sensible to replace them whilst the bottom of the engine was accessible.

 

[BMWZ4MC]

The very short term data (read unreliable) is that if you replace the rod bearings with the upgraded ones from VAC or Bimmerworld, then you are going to triple the bearing life. Common sense says that if you put OEM bearings back in................

Just a thought: if bearing shell wear is caused by occasional lack of oil between the bearing shell and crankshaft surfaces and if you fit bearing shells which last 3x longer, then they must be made from materials which are harder than OEM. Therefore, if harder bearing shells are coming into dry contact with the crankshaft, is this not going to transfer the problem into one of crankshaft wear as well as bearing shell wear? Although having to replace worn bearing shells is an expense and inconvenience, is it not cheaper and easier to do this again rather than have to also do remedial/replacement work on the crankshaft at a later date?

I understand that a proper running in period of <5000rpm for 1200miles (same as a new engine) should be observed when new bearing shells have been fitted.

I was told that it didn't really require running in, but I didn't exceed 5,000rpm for the first few hundred miles after mine were replaced.

 

[XMetal]

This was written around the time the S54 Bearing issue was in full swing. Interesting read:

http://www.shipkiller.com/StoneWalk_s_S54_Failure_History.html

Very interesting read. Has anyone heard of bearing shell failure affecting a Z4M or are there just reports of wear when inspected as a proactive maintenance step? Incidentally, mine were inspected at 50,000 miles (mostly enthusiastic road use but also quite a few trackdays) and they weren't worn excessively or showing any evidence of oil starvation, but it seemed sensible to replace them whilst the bottom of the engine was accessible.

Here's one recent example => http://www.zpost.com/forums/showthread.php?t=860093