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Old 11-28-2007, 03:09 PM   #12
Rajaie
Registered User
 
Join Date: Nov 2007
Location: Raleigh, NC
Posts: 1,268
My Ride: 528i 06/00
The BMW TIS (software repair manual) and in mimic the Bentley manual do call for resetting the engine timing when replacing the vanos. But there really is no reason to do so. I don't know a good reason why this is called for. Removing and replacing the vanos on these engines (M52TU, M54, M56) does not disturb the engine timing. Other engines like the M52 do disturb and need to reconfigure the timing when replacing the vanos.
The engine timing is set in the sprokets and chains and that is not disturbed. The splined shafts (helical gear cups) can even be theoretically removed and replaced without disturbing the timing. The splined shafts are keyed. Many owners, and I expect mechanics, have replaced the vanos without resetting the timing. Many have performed the vanos seals repair without resetting the timing.
It's also precarious to reset the timing, even with the special tools. I know two owners that have attempted to reset the timing (for non vanos issues) and have failed and are receiving fault codes. They used the special tools. I have spoken with one mechanic who has had trouble with this.

I understand that since the TIS calls for resetting the timing that owners will be concerned that it's necessary. I need to find a way to speak with some BMW dealership mechanics to see if they have an explanation for this. Maybe BMW felt that while so many components were removed that it's a good opportunity to reset the timing.

There is no reason to disturb and reset the timing when performing the vanos seals repair kit installation.
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