7.3 lazy lifter fix
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5th Wheeling
Joined: Aug 2022
Posts: 36
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7.3 lazy lifter fix
Recently my truck has been making a very noticeable *thump thump thump* sound at idle, especially when cold. Driving for longer than 15 or so minutes seems to clear it up, but it returns next time I cold start it. Pulled the valve covers and found that #7 exhaust lifter (farthest one back on the passenger side) is soft. All the other lifters are solid when I try to actuate the rocker, but that one has a fair bit of spring to it. Cranking the truck with the IDM fuse pulled I can see that its not pushing the valve down as much as it should be. I know my LPOP is weak, and I have a Melling replacement on the way, so I'm hoping the increased oil pressure will help, but does anyone know if there is a way I can alleviate the problem without pulling the head to replace the lifter?
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5th Wheeling
Joined: Aug 2022
Posts: 36
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I did pull the pushrod and check, it's straight. I can grab the rocker and rock it back, pushing the pushrod down, but when I let go it springs back. I'm hoping that this is just an issue being caused by stiction, since it just seems like the lifter isnt getting pumped up by oil it could just be a clogged oil passage. Im going to try a big dose of hot shots secret and hope that that helps it.
Lead Driver
Joined: Apr 2016
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From: Bahstun
Is oil coming up the push rod like the others?
If you dont have the oil, then maybe a passage is blocked.
if you have oil coming out like others, Lilfter might have a failed check valve
oil additives have never worked for me and stiction on a 7.3 is usually related to cold starts on the injectors as the clearance is only .004 on the solenoid
If you dont have the oil, then maybe a passage is blocked.
if you have oil coming out like others, Lilfter might have a failed check valve
oil additives have never worked for me and stiction on a 7.3 is usually related to cold starts on the injectors as the clearance is only .004 on the solenoid
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5th Wheeling
Joined: Aug 2022
Posts: 36
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Ok, I'll check for oil out the pushrod when I do the oil pump. There was oil pooled around the injector when I was investigating it the other day, and the pushrod didn't look worn at all so im assuming it has oil. I suspect it is a stuck check valve, hence my comment about stiction. If it is, is there anything I can try to fix it, or will I have to replace the lifter?
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