[sowbmw]

Is the vanos rattle due to a loose vanos camshaft sprocket adjuster bolt a common issue on the n55 engines (there are multiple threads about the 4 smaller bolts on the back shearing off, but I'm wondering about the long bolt that goes through the sprocket to the camshaft). Is it necessary to replace these as preventative maintenance. I've seen a couple threads about early cars having issues, but not too sure if this is something all n55 owners do proactively.

[CLEAN13BOOSTED]

Are the bolts indicated as one time use only? That's typically only "replace after removed" Torque to yield fasteners. Not sure that I've see where the bolt for the cam sprocket has been replaced proactively as part of maintenance.

[sowbmw]

I will have to check the specs, but it seems like there was a recall on these bolts. I looked at my vanos sprocket and it is wobbling a bit, but this could be because of the 2/4 sheared bolts on the back of the sprocket, which i will replace.

I'm just wondering if I should proactively replace the two long bolts while i'm in there because of the recall years ago.

[CLEAN13BOOSTED]

Since your already in there its always a good idea to replace fasteners(bolts). Cost factor is worth it! My opinion.

[yupetc]

Those bolts are torque-to-yield, one time use only. Has to be replaced or else upon re-using the old bolt will get you the wrong plastic deformation values from bolt stretch properties; you'll likely end up with the bolt backing out and cause you catastrophic failures. Do not skimp on these bolts.

[sowbmw]

I won't be touching the long camshaft bolts, but the general consensus is that I should just by the timing kit and replace the two long bolts mounted on the front of the vanos units (I still need to check if its loose).

Does that sound about right?

[yupetc]

Originally Posted by sowbmw

I won't be touching the long camshaft bolts, but the general consensus is that I should just by the timing kit and replace the two long bolts mounted on the front of the vanos units (I still need to check if its loose).

Does that sound about right?

Sounds about right, but just note that those cam gear bolts can only go on and get tightened once, and it relies on stretching the bolt a certain way to keep the gears in place. So whatever you do, just hand-tight everything up first, keep the gears loose, then set your timing brackets in and make sure all else are tightened and keyed in the right place, then you can go for full tightening of those two bolts. I don't remember the actual spec, but you're supposed to use torque wrench to tighten it up to a certain number, then do an 180-degree beyond that to utilize the TTY properties of that bolt. Once the bolt is TTY'd, if you ever losen it again, you cannot re-use the bolts. (Technically you can, but the risk is high for it to come loose again)