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      12-02-2010, 10:50 AM   #13
onebluemcm
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Having had an '04 M3 and spent lots of time on M3 Forum reading about this issue, I will say a few things to add to rclem05 has said so far.

BTW, rclem05 - please post mileage, just to add more data to the growing picture of this problem.

What I have gathered is that if there is any suspicion that these cam gear bolts are loose, they should be pulled and replaced, not re-torqued. It's somewhat unclear as to the exact cause of the problem, but the leading theory is that it's due to the bolts being incorrectly torqued at initial assembly.

Also, it seems as though BMW has recognized that there is a problem because the original bolts have already bee superseded with a new bolt that appears to have a form of loctite pre-placed on the bolts. It also kind of bugs me that they are being called VANOS bolts - these are specifically the cam gear bolts holding the cam gear to the cam shaft. You lose these bolts and you will have major valve and piston damage.

Because the S54 is normally a rather noisy engine, for lack of a better term, it seems like this rattle that comes from loose cam gear bolts might be hard to discern however, as rclem05 noticed, others have notices a new, lower pitch rattle that persists across rpm bands. From what I've gathered, the most important thing is to be in tune with the way your engine sounds as this is the best way to notice a change. If you notice a change in the way it sounds, time to get it looked at.

It seems that engines with a wide range of mileage on them are being affected. I've seen reports of cars with less than 20k miles being affected, and one guy with an M3 had this problem with over 90k miles.

It seems like a random problem that is not occurring with any particular cause or time frame - aggravating to say the least.
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