Fordtechnician Posted August 27, 2009 Share Posted August 27, 2009 My tech put one of these together (head gasket repair). He didn't hand turn over the engine first to make sure all push rods, rockers etc stayed in place. It missed when started. #2 and #8 missed. When the vc was removed he found the valve bridge on a pair of valves for each affected cylinder came off. It also destroyed the rocker arm ball that rides on the bridge. Also BOTH keepers came out of one of the valves. Nothing fell out and into the pan. All the pieces were found. Can air be added to that cylinder to hold the valve up so the keepers can be reinstalled? Right now the bridge is wedged against the spring and rocker....I think that is what prevented the valve from dropping. What are the chances the valve(s) bent? Quote Link to comment Share on other sites More sharing options...
GregH Posted August 27, 2009 Share Posted August 27, 2009 I would expect that you could add air to the cylinder to reinstall the keepers... The real question is what caused the bridges to fall off. If the tech is absolutely certain they were installed properly, then the valves most likely stuck and have been struck by the pistons and bent... Off with it's head. Again. Quote Link to comment Share on other sites More sharing options...
Fordtechnician Posted August 27, 2009 Author Share Posted August 27, 2009 I would guess the bridge was installed incorrectly. I guess thats what I am hoping for. Quote Link to comment Share on other sites More sharing options...
Aaron Posted August 27, 2009 Share Posted August 27, 2009 That valve is likely bent. Air up the hole and get the keepers put back on, then do a compression test while you're there. Just my .02 Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted August 27, 2009 Share Posted August 27, 2009 Not sure I'd bother with the comp test... air up the hole and listen for an air leak... a poor mans leakdown test. Remove the EGR vale and listen at the intake... also listen at both the EGR port as well as the tailpipe just to be sure. A 'real' cylinder leak test would have the piston at TDC. Quote Link to comment Share on other sites More sharing options...
Aaron Posted August 27, 2009 Share Posted August 27, 2009 Yeah, good point. I kinda overthought that one. Quote Link to comment Share on other sites More sharing options...
Fordtechnician Posted August 27, 2009 Author Share Posted August 27, 2009 300 psi on #2. Currently taking it on #4. Quote Link to comment Share on other sites More sharing options...
Fordtechnician Posted August 28, 2009 Author Share Posted August 28, 2009 #4 was the same. WONDERFUL!!! It runs fine now. I was sweating. I am the SM at the dealer and it is / was a warranty job. Quote Link to comment Share on other sites More sharing options...
blown99 Posted September 3, 2009 Share Posted September 3, 2009 300 seems low?? How about a relative compression test? Quote Link to comment Share on other sites More sharing options...
Mekanik Posted September 3, 2009 Share Posted September 3, 2009 I have seen a guy screw up valvetrain on a 6.0l headgasket job by not removing the rockerarms from the cylinderhead. He thought he would save time by leaving them installed on the cylheads, and trying to line up the pushrods while installing the heads. It didn't work out too good. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 3, 2009 Share Posted September 3, 2009 300 seems low?? How about a relative compression test? To me, the relative compression test can be a scarey test... If you have an identifiable miss, it *may* direct you to a cylinder if needed (say if MP_Learn is toggled at <NO>) or it can help eliminate an injector as a cause of misfire... As a "real" diagnostic tool, I don't think it holds a lot of value. Quote Link to comment Share on other sites More sharing options...
joshbuys Posted September 4, 2009 Share Posted September 4, 2009 300 IS COMPLETELY ACCEPTABLE, DEPENDING ON ELEVATION. AT HIGHER ELEVATIONS YOU WILL GENERALLY SEE AROUND 300 - 330 PSI. WHEN I USED TO WORK DOWN AT SEA LEVEL, THEN IT WOULD HAVE DEFINITELY BEEN AN ISSUE SINCE WE GENERALLY SAW MUCH CLOSER TO 400 PSI THERE. I'M OVER 5000' ABOVE SEA AND WE SEE A GOOD ENGINE WITH ABOUT 310 PSI. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted September 4, 2009 Share Posted September 4, 2009 400-410 is what I see here near sea level. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted September 4, 2009 Share Posted September 4, 2009 We went through this recently on a 6.4.... we're at about 1900 feet and everyone thought my numbers were way low... even after comparing to a brand new truck. I have, for a long time, used compression testing as a relative measure rather than an absolute measure. I am still a great big fan of the cylinder leakage test. Quote Link to comment Share on other sites More sharing options...
joshbuys Posted September 5, 2009 Share Posted September 5, 2009 Just remember, the 'relative compression test' is just that "relative", I don't trust it much on a 6.4 as I had one that was missing pretty bad, all kinds of smoke, #8 was below -60 on power balance. Relative compression showed 0% varriance on all cylinders. Didn't quite sound right when cranking, so I thought I'd do a manual compression on it and would you believe that cylinder 8 was around 50 psi with all others on that bank around 320! Some 'relative' compression! That was my first experience with a blowed up 6.4, and now it seems like a normal occurence for me! Quote Link to comment Share on other sites More sharing options...
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