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Discussion Starter #1
So, a couple months ago I was driving from North of Seattle Washington about 3hrs to Portland OR to pickup a 2door Tahoe at a buddy's house that I had purchased. About half way down to Portland while in stop and go traffic my flatbad started making a knocking noise. The noise was loud at first then quited down some. Made the trip Tahoe in toe back home. The noise went away for the majority of the trip back, started back up again about 20 miles from home. I swapped some injectors out with the problem still persisting. Came to the conclusion that it must be valve train noise. Pinpointed the suspected cylinder #4, removed that valve cover and rocker assembly and lifter. Here is what I found.
 

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Ewww, that sucks.

Looks like your barking up the right tree though... maybe a collapsed lifter or bad/failed guide? :confuzeld
 

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Looks more like lack of lubrication to me. I'd be checking the cam for tracks worn in from the rollers on the lifters. Lifters can be removed without pulling the heads.
I bought a truck with "blown head gasket" that had been driven to several shops for quotes in very cold weather. The oil got thicker than grease. The main and rod bearings looked ok for 300K miles, but the top end was starved because the oil was too thick to pump through the smaller passages. All the rocker arms were worn like that and the cam had tracks in it along with spun cam bearings.
 

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What's the oil pressure when you're at temp, sitting at idle in drive? And does anyone know what it "Should" be?

I've seen mine go down to 25-30
 

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Discussion Starter #5
Bk95td, I pulled that lifter and disassembled it, found some noticable Ware on the upper end of the bore. My thought was that was where it hung up allowing excessive lash- pushrod to rocker arm length causing the ware on the valve stem tip ? The roller of the lifter looked smooth / and inspection of the cam on that lobe I see no obvious ware or unusual marring or markings. Wondering if I can just file or grind the valve stem smooth ? I believe they are stellite valves? Is that material hardend thru so if I file or grind it the material is the same thru the whole stem? Also was planning on replacing the rocker arms with new or almost new with less noticable ware. Some posts that I read with similar condition there was recommendations of valve lash caps , any thoughts on using them ?
 

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Discussion Starter #6
I should clarify the ware on the lifter was internal on the piston bore.
 

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Discussion Starter #7
Rambos ride, on the oil pressure I'm not sure what it should be. What I have seen with my trucks is that the pre-oil squirt blocks seem to have overall higher oil pressure but still at temp idle come down to 30 or so psi. The engines I have with piston cooling spray nozzles seem to exhibit a more variable oil pressure at temperature idle 30+ upper rpm 40-60psi more prominent fluctuations. Not sure if that makes sense and may not be the same with all engines depending on age milage and internal condition.
 

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Discussion Starter #8
So, my decision to make now is should I get a set of lifters and replace all of them on that side while it's apart and also get new pushrods as well so everything is fresh ? With having to pull the intake and injection lines ect to get to the valve cover, hoping to successfully get this repaired and have this behind me.
 

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Looks more like lack of lubrication to me
Yea I didn't even think of that.

Bk95td is on it lol. Subbed and just seeing how this one plays out. Curious.

Plugged or restricted oil gallery????
 

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You would be better off changing all of the lifters and rockers. It wouldn't hurt to install a new HV/HP oil pump at the same time..



You could use lash caps but you would need to use them on all places.



And push rods, check them all to see if any are bent..
 

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Discussion Starter #11
sctrailrider, what's your opinion on the roughed up valve stem tip ? File or grind ? Obviously pulling the head and replacing that valve would be the better choice. Or the valve lash caps on all valve stems?
 

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Discussion Starter #12

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sctrailrider, what's your opinion on the roughed up valve stem tip ? File or grind ? Obviously pulling the head and replacing that valve would be the better choice. Or the valve lash caps on all valve stems?

If you are going to go through the heads I would replace that valve, I have a set of standard valves from a P400 that are new if you need them. A standard trip to a head shop for crack checking and a valve job would be what I would advise. If they wind up cracked it wouldn't be wise to spend much on them...
 

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Discussion Starter #14
I am trying to avoid pulling the heads on this truck, as I have the other Teds engine I was going to be going thru it is for my suburban.
 

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Discussion Starter #15
Here is where I am at presently, I have a new set of sealed power lifters, and pushrods. I pulled the remaining rocker assembly pushrods and lifters from that side of the engine. This is what I found I'm concerned about how much scuffing there is on the outside surface of them, this engine is a Navistar casted block that the previous owner built and is supposed to only have about 100k on it. Seems like excessive ware to me? I'm concerned maybe when he did the rebuild that he used a standard output oil pump the truck is a 1995 , he may have not known about the requirement of the HV oil pump for the newer engine.
 

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Discussion Starter #16
I've rolled the engine over and all the cam lobes look good. I think checking the oil pump is next up, to make sure it is the HV version. As far as installing the new lifters I find mixed opinions. Soak in oil, fill with ATF and lube the roller w/ lubriplate 105 ? Any comments on lube for installation of the new lifters ?
 

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Those appear to have a LOT of wear, I would guess if you were to bore gauge the lifter bores they will be over sized..


But if you just want to freshen things up for a while new lifters will work, the 105 will be good on the body & roller, I wouldn't use trans fluid google can show you how to prime them if they aren't already...
 

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Discussion Starter #18
I'm thinking I'm going to need to do the other side as well. After this the block will probably be junk, I haven't heard of them sleeving the lifter bores or making oversized lifters ?
 

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Discussion Starter #19
Made a little more progress on this today, got the new lifters, pushrods and almost new rocker arms installed on the passenger side today. Plan to do the driverside tomorrow.
 

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Discussion Starter #20
Few more pics of the valve stem tip I was able to file it lightly and a finishing touch up with a diamond hone. Rockers bolted up.
 

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