slight valve to piston contact...jumped timing?

[exhaustfumes]

for those of you who recall, my 2.7 seemed seized on initial start-up. then it turned out it just wouldn't make 2 full revs, something was blocking inside. pulled the heads last night (those cam nuts are really awful), and was figuring i would see jimmy hoffa in there, or at least a valve head flying around a cylinder. nope.

#4 cylinder has a clear but slight mark on the piston crown from the exhaust valve, an arc about 18mm long, and #6 looks like something small and hard might have been in there for a few revs, a few light gouges at the very bottom of the piston (i could have dropped a washer in there while pulling the CIS stuff off, and then spun it a few times after removing all of the rockers??), but all valves look OK. lots of carbon, but no massive chunks.

here is what i am thinking....this car has pretty crappy oil pressure, and hyd tensioners. could the one bank have jumped time during cranking? has anyone every experienced a jumped-timing incident during start-up?

thnx for your ideas....joe in NJ

[Eagledriver]

That seems like a likely scenario. Another possibility is an over-rev and bent valve not closing. Sounds like time for a rebuild. If the car has crappy oil pressure you'll need to do the bottom end as well.

-Andy