As your V8 has a timing belt and not a chain, I'm confused by references to a chain.
Timing belt VS Camshaft chain in overhead Cylinder head.
00 2000 Audi A6 C5 4 2 Driver Side Engine Cylinder Head | eBay
Picture shows the chain on the right(engine front), where the tensioner in the middle controls the slack in the chain.
The exaust camshaft went out of alignment with the intake camshaft by one tooth of the gear.
Which parts were replaced and which parts were NOT replaced as part of the timing belt job?
Did you buy the parts or did the mechanic source the parts?
The reason I ask is there are a few possible failure points :
1. Engine was not timed properly when belt was reinstalled
2. Loss of tension in the system
3. Broken tooth on belt
Obviously part of putting a new timing belt on involves checking timing, tension, etc.
If you have known the mechanic for 7+ years I think you are entitled to ask some HARD questions.
Timing belt kit with water pump from Gates, Behr thermostat, accessory belt Gates, spark plugs Denso NGK.
All parts sourced and brought in by me.
1.Timing was done correctly I assume, as the tech did check the timing through the computer after completion. In addition the engine worked perfectly fine and noticeably smoother than before (or so it seemed). The skip in timing happened I am guessing on startup the next morning, as it couldn't have happened overnight with the engine off, and it worked great with no CEL the previous day up to being turned off.
2.Loss of tension in the camshaft chain in the cylinder head is obvious, as the plastic guide of the tensioner is gone, but was it that way for a long time before or not no one knows. The issue is why did it decide to disintegrate all of a sudden and did it work fine in the same condition(no plastic guide) all this time prior to the timing belt job.
3.I assume that he had enough experience to check the brand new parts for the possible defects, which are unlikely in themselves.
Please help me find a connection between doing the timing belt job and the camshaft chain skipping a tooth the next day. Why didn't it happen right away or before getting home?
Accessory belt connection?
Where is the cam position sensor's role in all this?