batmantech Posted October 5, 2010 Share Posted October 5, 2010 Have 08 124,000 miles 6.4 miss, #1 rocker arms not moving push rod out of position. I read past posts on this people had valve stuck in head so I will be looking at that next. My question for those of you who have experience on the 6.4 is this. Power balance showed only #1 -60 all others ok, relative comp was different, #1 21% #2 12% and #5 7%. Is this somthing I should be concerened about. Is it just an issue with one head or do they generaly both have the problem, Is it the old as long as it is apart go after both heads? Any feedback would be appreciated as I have little experience on the 6.4 Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted October 5, 2010 Share Posted October 5, 2010 I think we have pretty much determined that the relative compression test is big-time unreliable. Only a manual compression test will be of use to you and I can tell you that for warranty purposes it must be performed. I suggest doing a compression test before disassembling ANYTHING. I have had one run-in with seized valves in a 6.4L and If I recall they were the exhaust valves in cylinder #1. One thing I noted was when watching my power balance display the failure in cylinder #1 was affecting performance of cylinder #3 and #5 to a lesser degree. This particular truck had a sharp popping noise out the intake as whatever combustion that was taking place was let out of the intake valves which explains the affects on the other cylinders. The three things that have proven most effective in diagnosing base engine problems on these engines are short term fuel trims, manual compression readings and careful tear down and inspection. The more of these you work on the more you will become familiar with the terms "piston partrusion" and "cylinder washing/glazing." Oh! On that engine with the sized valves the concern was confined to the one cylinder. If the valves can be removed from the head it is repairable. Quote Link to comment Share on other sites More sharing options...
Mikill Posted October 6, 2010 Share Posted October 6, 2010 I have noticed that on valve train concerns that relative compression is off on more than one cylinder. When exhaust rockers arm break or exhaust side has problems there is usually a loud popping out of the intake but when there is a problem with the intake side there is no popping to indicate a valve train concern. Quote Link to comment Share on other sites More sharing options...
Steve Mutter Posted October 6, 2010 Share Posted October 6, 2010 I had a 6.4 that showed signs of wear on the rocker tips and on the push rods. That tip should not be flush in the end of the rocker tip(I wish I had a picture to explain) I think when the clearance gets too the push rods almost falls out. If there is enough wear on the valve train maybe thats why you have funny relative compression readings. In the truck I worked on it had a lack of maintenance problem. Just something to inspect as well Quote Link to comment Share on other sites More sharing options...
mchan68 Posted October 6, 2010 Share Posted October 6, 2010 I don't know about the rest of you guys, but I haven't much success with attempting relative compression tests on these engines because the engine has always ended up either firing up in the middle of the 10...9...8... countdown, and/or the pop-up window appearing, to indicate excessive engine RPM change when doing so. I always assumed that the relative compressions on ALL vehicles did so by disabling fuel (and spark on gassers), so I can only assume the engine is firing up due to ingesting a residual alternative fuel source from SOMEWHERE else. The point being, like Keith already pointed out, attempting this test is as good as useless. Quote Link to comment Share on other sites More sharing options...
Mikill Posted October 6, 2010 Share Posted October 6, 2010 I don't usually have any problems when using relative compression test. It's not always accurate but it has been useful to me many times in pinpointing problem cylinders. Quote Link to comment Share on other sites More sharing options...
batmantech Posted October 20, 2010 Author Share Posted October 20, 2010 update--This truck is under a fleet waranty. We told them the head needs to come off. They wanted to "try" just rocker arm and push rods first....The thing made it 80 miles before throwing a pushrod. The fleet company then decided not to fix the truck, they towed it away. I thought you guys might find that interesting. Quote Link to comment Share on other sites More sharing options...
fordtech03 Posted January 12, 2011 Share Posted January 12, 2011 I came across this thread while researching one that I have in my bay now... #2 pushrod is bent(exhaust valve), rocker is loose, tip is worn but I have no base oil pressure.The Hotline said to replace the valve train components and check for a rotated lifter...but we are thinking just a failed lifter will not cause a 0psi reading on base oil. The vehicle is under warranty so my service manager isn't really wanting to hang any parts on it just yet for fear of the claim getting kicked if it needs some major repairs after replacing these parts. The truck will run, I have 0 psi reading on my gauge coming off the EOT tap, the filter housing eventually fills with oil, but not when just cranking the motor over. Took the pressure regulator out and it seemed to be ok. I'm thinking that maybe the valve train failure sent some junk in to the pump and cracked the gears or something causing the base oil concern...anyone else ran into something like this? Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted January 12, 2011 Share Posted January 12, 2011 The only thing I have seen even close to the problem you have was a failed roller lifter that sent needle bearings into the pan on a 6.0L. That does a number on the pump but I don't recall a moss of oil pressure. Of course, you can simply remove the pump cover and see for yourself what you have... Quote Link to comment Share on other sites More sharing options...
hitechmech Posted January 13, 2011 Share Posted January 13, 2011 I'm currently working on one that had extremely low oil pressure and cyl 4 push rod with the tip broken off, necessary to remove pan to find tip of push rod and found pieces of gears off the rear drive train. Now in the process of removing trans the see why and to what extent the damage on the gears are. Wondering if there still are engines out there with incorrect gear clearances? Quote Link to comment Share on other sites More sharing options...
cbriggs Posted January 17, 2011 Share Posted January 17, 2011 If a lifter is out of its hole (for whatever reason) you will have very low oil psi. Quote Link to comment Share on other sites More sharing options...
fordtech03 Posted February 19, 2011 Share Posted February 19, 2011 Just an update..we replaced the oil pump, the rocker bridges and the push rod as per Ford's recomendation. It had a bit of a "knock" to it but ran fine....released to customer, of course we told them it would be back eventually. It is sitting in my bay again :-) Motor is locked up, got he RH head off, all 4 valves contacted the piston, pulling the other head on Monday in hopes of a longblock instead of one of these "robust" short blocks....so far even after seeing the valve contact marks on the piston there is no obvious damage to the head. Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted February 19, 2011 Share Posted February 19, 2011 I am pretty sure Ford's term for that is metal transfer, and that will require a longblock. Quote Link to comment Share on other sites More sharing options...
Keith Browning Posted February 19, 2011 Share Posted February 19, 2011 How did the piston look besides the valve impressions? I have seen many 6.0L and 6.4L pistons where the crown has begun to melt resulting in what Brad mentioned as metal transfer. It seems like it causes the piston crown to grow which may have been the source of that knock. We know the rods are not going to stretch. Often when I see this the edge of the piston crown is rounded and there is scoring of the cylinder walls as well. Quote Link to comment Share on other sites More sharing options...
fordtech03 Posted March 4, 2011 Share Posted March 4, 2011 The pistons looked fine....went to turn the motor over by hand and realized only #1 and # 2 were moving. Dropped the pan and it was full of metal from the bearings, a few various chunks of piston and crankshaft...It had twisted and snapped the crankshaft in front of the main cap, oil pump was busted of course. Got a "short" block for it with heads seperately because that how Ford warranty wants it now, they are really pushing these "ROBUST" shortblocks now. Quote Link to comment Share on other sites More sharing options...
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