Originally Posted by
djb2
How did it jump a tooth?
Empty hydraulic lifters put a lower load on the camshaft.
Hydraulic-assist tensioners (at least on BMWs) have a spring pre-load and are on the slack side.
There is more of a risk with pre-filled lifters, which haven't had a chance to bleed down to the right level.
I didn't worry at all about wear on the first start. I was much more concerned about wear during a zillion incremental checks during assembly, especially when verifying the cam timing. Every bearing surface was assembled with a drop of oil, and I repeatedly drizzled oil over the camshafts during checks.
On a related note, assembly lube is often over-used. Regular oil is preferable if you are building the engine to use in the near future. Assembly lube should be used when the engine might not be used immediately, especially if your projects tend to confuse weeks and decades. Or very sparingly when you need to briefly hold a part in place.
Apparently the cam chains on this Audi V6 (from an A5 Quattro) are relatively loose until the adjuster pumps up. The engine had sat for who knows how long in a warehouse, and I'd replaced all the leaky oil gaskets that reside under the intake. So, I'm sure the oil galleys were pretty empty. On startup there was a lot of cam chain noise for a few seconds until the adjusters pumped up, then it started throwing codes for timing, and running rough. Upon further examination the exhaust cam on the driver side had skipped a tooth.
Current stable:
2002 525i (Daily Driver)
1994 SN95 Mustang 'Vert (The Bumblebee)
2001 325i Convertible (Beach cruiser project)
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