Engine knock S54

B

Beemingallover

Member
The engine on my E85 Z4MR, 95k mls, recently developed an intermittent rhythmical knock. It's not a rattle, a definite solid knock. The shells and bolts were replaced with ACLs at 75k mls, the Vanos seemingly runs smoothly, cam and rockers seem innocent. As I mention the knocking is intermittent, with the knocking not in evidence on every running. But as fear of destroying the engine, the engine has only been run two or three times since.
The knocking occurred on idle and at higher rpm. The engine runs cleanly and normally during knocking. Last oil change at 93k mls.
No trace of debris in oil.
Any suggestions pls?
 
Worth doing a vanos test using ISTA, I heard of a similar issue and it was the vanos solenoid block failing.
 
if your local to West Midlands, I can run the test for you, although the engine needs to be a running temperature for accurate results.
 


Sound like that?

That was mine when the lifters flattened and scored the camlobes on my first trackday after purchasing it.....
 
Soun
Ed Doe said:


Sound like that?

That was mine when the lifters flattened and scored the camlobes on my first trackday after purchasing it.....
Click to expand...

Sounds similar without the rattling, just knocking.
But the knocking is not all the time, other times normal. Weird. Engine runs well apart, even when knocking.
Only occasionally running engine for fear of terminal damage.
 
Whip off the cam cover and give everything a visual check/ check lifters and valve clearences as a first point of call. Also chain for excessive slack on the chain at the front of the engine. Could be the front chain guide has broken and is rattling around occasionally, or possible the vanos tabs have sheared off.

You'll be able to see what's going on that way and can check everything is in order.
 
0l0dom0l0 said:
Whip off the cam cover and give everything a visual check/ check lifters and valve clearences as a first point of call. Also chain for excessive slack on the chain at the front of the engine. Could be the front chain guide has broken and is rattling around occasionally, or possible the vanos tabs have sheared off.

You'll be able to see what's going on that way and can check everything is in order.
Click to expand...
Thanks. Seems the best area, but nothing showing on the cam. Weird, the engine runs normally apart from knock. Bearing in the water pump?
 
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