Pelican Parts Forums

Pelican Parts Forums (http://forums.pelicanparts.com/)
-   911 Engine Rebuilding Forum (http://forums.pelicanparts.com/911-engine-rebuilding-forum/)
-   -   slight valve to piston contact...jumped timing? (http://forums.pelicanparts.com/911-engine-rebuilding-forum/288799-slight-valve-piston-contact-jumped-timing.html)

exhaustfumes 06-16-2006 01:45 PM

slight valve to piston contact...jumped timing?
 
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 06-16-2006 02:24 PM

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


All times are GMT -8. The time now is 07:44 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2025 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website


DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.