Had a bent push rod, replaced but still misfires - Ford Powerstroke Diesel Forum
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Old 01-29-2012, 07:43 AM
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Had a bent push rod, replaced but still misfires

I just bought this truck. It had a bent push rod, the shop I bought it from said they had been starting it with either because it wouldn't start without it and it bent. I tore it apart and did head gaskets and studs, had the heads machined, new oil cooler, egr delete, one new push rod (exhaust, passenger side rear most cylinder) all new gaskets, seals, o-rings, injector o-rings. Started it up and it still misfires but not like it used to, no huge popping noise anymore. Cranking it sounds like it is low on compression. I looked at the valves but did not pull them, looked at the cylinder and it looked ok, the piston had a little extra carbon, but the truck was driven in and out of the shop on 7. Looked at the lifter and but didn't pull it, didn't look like it had any damage. Smokes white smoke out the exhaust. What did I miss?
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Old 01-29-2012, 11:17 AM
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Did you check the FICM and batteries?

MikeB
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Old 01-29-2012, 02:56 PM
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Is it still missing on cyl #7? since it was an exhaust pushrod that was bent there is a chance there's still a problem with that lifter. You really should have pulled it out and had a look. If the exhaust valves aren't sealing there's your source of white smoke

edit - oh wait, I forgot you can't pull that lifter out because of the branch tube, sorry

Last edited by sinner6.0L; 01-29-2012 at 02:59 PM.
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Old 01-29-2012, 05:11 PM
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I didn't pull the lifter, looks kinda like the engine has to come out of the truck to get that oil tube out of the way. It set a code for cyl 7. I was going to unplug the injector to see if it stopped smoking but it might be a waste of time. I think I am going to pull the valve cover off and have a look inside. Seems like a mechanical problem, not a fuel problem. The batteries are good and I put new FICM connectors on because all 3 were broken. Truck starts right up and seems to run fine on the other 7. I might have a messed up rocker, looked ok but who knows.
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Old 01-31-2012, 05:05 PM
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I pulled the valve cover off and found a broken rocker arm. The push rod was bent too, but not to bad. So what I want to know is if this is a plausible theory: Because the push rod was bent the hydraulic lifter pumped up all the way and hyper-extened, causing to much rocker movement and with no where to go it broke. I don't really want to pull the engine to get at that lifter if I don't have to.
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Old 01-31-2012, 06:27 PM
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I think I have a bent valve, cant move the lover one. Can't be bent drastically, they all looked straight with the springs on.
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Old 01-31-2012, 07:31 PM
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you should be able to push the valve open by hand even if it is hard.. if not you need to pull the head back off and fix what ever is the problem. if it does open, put a new rocker on first and try it out.. the rocker could easily have been broke when the push rod bent.. im not sure if there is hydraulic lifters(98% sure there is) if they are pumped up too much, worst case scenario, the valve would be held open for a minute till it bled down and adjusted it self. it wouldn't cause that damage
it only takes a few thousands of bend and the valve wont fit through the guide.. most likely if its bent, it would of been forced down and stuck open.. you could have other problems under the head in the cylinder blocking the valve. take the rocker off and tap the head of the valve spring with a hammer and see if it moves, don't smash it like it owes you money though, just see if it pops open and closed.. i have seen some videos of starter fluid doing some pretty knarley damage on an engine..
you said you had the head off. what did the cylinder look like? what did the combustion chamber and valves look like under neath?
if you are that far into it, you really should at least get the valves checked.

Last edited by j1mmy; 01-31-2012 at 07:43 PM.
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Old 02-01-2012, 03:53 AM
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Are these engines interference? Is it possible that the valve got held open or stuck open and got wacked by the piston?
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Old 02-01-2012, 07:04 PM
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Ripped the head off again tonight, found 2 bent exhaust valves. Both valves had gummy carbon on the stems and didn't want to come out. Once I cleaned them off they both go in and out just fine, well except near the end where they are exactly straight anymore. The lifter goes in and out with the rotation of the engine. I think I mat just be a victim of my own lack of attention to detail, really should have checked those valves.
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Old 02-01-2012, 07:53 PM
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All it takes is once. I learned the hard way now when i take a head off it goes to the machine shop to get check, i dont care what it is or why its off it allways goes. I had to eat a saturn head once cause it "looked good".
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