3204 pushrod/valve failure

Anonymous-0 · Jun 29, 2011

Anybody got any ideas on a bent pushrod,scored and slightly bent inlet valve on a 3204 eng? The piston and connecting rod appear to have no play, the valves were WAY overdue on adjustment and have ALOT of clearence, Machine is a '89 Cat D4-C---RJ007544

Anonymous-0 · Jun 29, 2011

I've seen and heard alot of stuck valves on cat engines during cold start days. The valve may have been stuck open.

bob plumadore · Jul 1, 2011

Sometime when an engine shuts down it will "roll back" turn in reverse and the piston and valve will touch that will cause a bent valve and pushrod.

Fritz Maurer · Jul 1, 2011

Based on the available information, I would guess that the valve stuck open, the push rod got somewhere it wasn't supposed to be, and the piston came back up and closed the valve, mashing the push rod. The scoring is from something else,probably what got this whole thing started. This head ever been apart before? Can't think of anything that score a valve stem but faulty guide installation, maybe also repeated overheating. Another possibility, someone previously tried to remove a valve without removing any possible burrs, just yanked it through the guide and made a scratch which would reduce the clearance. Even though there could be plenty of oil in that guide, it could never lubricate that pin-point line bearing on the valve stem. Here's yet anther: Inspect the oiling system for reduced or halted oil flow to the rocker arms.Fritz.

Anonymous-0 · Jul 2, 2011

I've heard too much ether can bend push rods.

Mr. lee · Jul 3, 2011

Thanks to everyone who responded. We repaced push rod and valve on # 4 clylinder,adjusted valve clearance, inspected everything else we could think of and still don't know for sure how it happened. I don't use ether, the machine was warmed up and had been working at a fairly easy pace, never have got it hot. Oil pressure is good. Bought it used a couple years ago with no maintenence records but receipts showing a new short block. No receipts showing any head work at all. Engine has apprx. 800hrs. on short block. I'll check oil pump & delivery system before I work it. Thanks again.

tom Spivak · Jul 7, 2011

Can't see how a engine rolling back would cause the valve and the piston to touch, the mechanics just wouldn't let that happen.

d9gdon · Jan 13, 2013

(quoted from post at 21:20:54 06/29/11) Anybody got any ideas on a bent pushrod,scored and slightly bent inlet valve on a 3204 eng? The piston and connecting rod appear to have no play, the valves were WAY overdue on adjustment and have ALOT of clearence, Machine is a '89 Cat D4-C---RJ007544

I know this thread is old, but I ran across it while searching for the valve lash on a 3204 Cat that I'm working on now.

I just repaired a 3406 Cat engine that did this same thing. The end diagnosis was that the head had an old crack in it between the valves and it was determined that coolant would leak into the combustion chamber after a workday and after having sat for a couple of days, it rusted the valve stem causing it to hang up temporarily which let the push rod fall out of position on the stroke causing it to bend when the piston came up and knocked the valve back up. At least it usually doesn't bend the valve since it's positioned in the head vertically instead of angled like some engines.

Maybe this will help someone in the future.

3204 pushrod/valve failure

Anonymous-0

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Anonymous-0

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bob plumadore

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Fritz Maurer

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Anonymous-0

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Mr. lee

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tom Spivak

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d9gdon

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