rut-roh, compression low on fo
 

got a buddy that just rebuilt his 3.0 and ran it for a day or two, called me and said " it runs but rough" so first thing i do is grab my compression tester and head off, well #4 is at 30 psi and the rest are at 150 or close..... wth? i put oil in the cylinder and tried again, no movement at all on the test. what now?????:think:

find out where "compression" is goin, if you have acces to a leakdown tester hook it up, add air, listen @ the "710" cap, the exhaust, the intake, an check radiator for air leaking...
Sounds like something didnt happen during the rebuild, how indepth was the rebuild, jus a top end or lower aswell?

full rebuild, pistons and all. dont have a leak-down tester, where would i get one?

ok whats a 710 cap? :hillbill:

"OIL" upside down:hillbill:

check your local harbor freight, not sure if autozone has them in their loan-a-tool program...

he just said if it has anything to do with the head he'll buy a new one, so should i tell him, just get a head?:think:

wow, friend must be loaded. but what if its the rings are not staggered correctly? what if the valves are not seating correctly? what if the HG damaged during the install? what if one of the bolts wasnt torqued down properly? get the tool, youll gain knowledge, youll pinpoint the leak, an save your bud some money...hopefully.

no change in compression with oil in the cylinder indicates either real bad ring sealing or mis-adjusted valves, or other physical problem with the cam such as worn cam lobe(s) or problem with either bent stem or burned valve face or seat.

as mentioned a leak-down test should be done.

since the reading didn't change with oil in the cyl, my bet would be that the valve job was not done correctly on that cyl or the valve clearance is too tight

ahhhh heck with it, im buying a leak down test tool, i always need new tools:hillbill: . i'll check it out and see whats up...

Im willing to bet you have a mis adjusted valve. Its easy enough to pull the v/c on that side to check clearances

should i check those real quick just in case? dont i need speacial tools for a valve adjustment?:think:

Well I would check it, then depending on the outcome, worry about finding the right tool to do the adj. Worst case is you take off the tbelt and remove the cam to gain access to the valve shims