Thread: Head gasket and rocker arm failure - Cause?

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This engine was rebuilt using Holley Systemax components about 3000 miles ago. I removed the engine from my friends Jeep (was running well), externally refreshed it, and installed it in my Jeep. So there is a history of it running good with no problems. Same internal, dist, carb. Only changes were re-setting timing, new fuel lines, valve covers.

Initial startup of a few minutes had misconnected vacuum lines, and timing was off. Ever since then (10 minutes total run time until now), the engine runs very poor with excessive valvetrain noise, and coolant leaking excessively into cylinder number 8. Upon disassembly, I found a head gasket failure in the 4 corner cylinder outer walls (see picture closeup). I also found 3 rocker arms with flattened roller tips. No other damage was found to the pushrods, hydraulic lifters, valves, springs, heads, or piston heads.

Felpro says this kind of head gasket failure is caused by excessively high combustion chamber temps (detonation, lean, etc).

The damaged rocker arm roller tips are at valve 1Exhaust, 5Exhaust, and 7Intake. Maybe the flat spot was over time, and not one incident? It has also been suggested a lack of proper lubrication cause failure (oil press never seemed unusual). I want to prent this from happening again on new components. If I just had the timing too far off and that did it, ok. If it is something mechanical, I want to solve it and not ruin more parts or the whole engine.

I have replaced head gaskets and rocker arms. I want opinions from anyone who has ideas of what might have caused this so I don’t just put it together and have the problem occur again. Has anyone seen this kind of failure before? Any ideas of other damage I may not have found that exists? Guesses, questions, and ideas are welcome. Thanks.

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Rocker looks like it was to tight. Motor looks kind of dirty for 3k miles??Is the dot on the back piston facing the rear of the motor??never took a 3K mile motor back apart but the cyl walls look shinny also, seems like it should still have some signs of the honing if only 3k miles??

Maybe 3k was too little. It was driven rarely over 3 years by a freind of mine. Driven hard too.

dots go to the front they are on the rods right.

dots go to the front they are on the rods right. the rocker look like they were running off the valve stems they should be in the center line of the valve look at your push rod guildes move them to get the valve in the center of the valve stem if you can not do it then use isky adj guide plates is will keep it from side loading the rocker and check the push rods make sure they are the right size not to long or to short . on them rockers i do not care much for them if you want roller i would get a set of crane or any thing but proforms or a stock shoe type with no roller tip oh by the way you do know them valve stem will have to be cut on the stems? to get them flat . and i would get both heads cut flat them holley head some times have crapy finsh on them out of the box . and it looks like the rocker were running on the valve retainers to lucky out did not blow it to hell .do them heads have any push rod guide plates? if not you need some

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Originally Posted by DennyW

I was looking your pictures over, and I got to tell ya, this this has been run hard. I see a ridge at the top, cylinder wall scratches, and lots of carbon type grit. And yes, the rockers do not look centered, and they are side loading.

ummm maybe i am looking at it wrong but are those pistons in the 1st pix even the same? and for a rebuild why would you even mess with cast pistons and it looks like the valve hit the gasket the gasket bore size is too small but ummm hey just wow never seen a rocker tip to that

I appreciate all the responses. After much analysis and talking to engine building experts, here is what I have found:

The head gasket and rocker arm failures are 2 different failures.

The head gasket was most likely damaged during installation by a moron. If you look close, the location of the gasket damage in the front to back direction is inline with the dowels (which were probably in the head during install). My best guess is that theey were damaged, but did not leak until I started the engine and stared fiddling with timing, etc. I have replaced the gaskets with the correct ones, so I'm crossing my fingers.

The 3 failed rocker arms were probably out of adjustment and had little or no preload (as opposed to 1/4 turn tight to the hydraulic lifters). ALSO the guide plates were never moved to align the rocker tips on the valve stem center properly. Therefore the offcenter rockers rode on the outer edge riding up and down the edge instead of across the flat valve stem tip. This may have caused them to loosen. In any case, they were loose, which caused them to start banging even harder. I am replacing the rockers with full roller rockers, and I will align the guide plates properly before, and then after pre-loading the lifters.


Short answer is that the person who built the engine up originally did a poor job at best, and that is what caused these failures. I have decided not to tear the engine apart to look for other mistakes.

Thanks again. Thought you would all like to know what happened.

Hmm... You know, what you really want to do is tear the whole thing to pieces and rebuild it again. It has different types of pistons, even some with dishes and some without. That thing is never going to run nicely, no matter what you do to the heads. The chap who built it didn't know really what he was doing (putting different pistons in an engine ) Maybe your heads weren't torqued up properly and lifting the engine (if you lifted it by some head screw holes) just dislodged it by a couple of thousandths, thus breaking the seal of the gasket. The compression and burning proces then did the rest. Maybe the dowels arent far enough in the block, then the heads wouldn't rest properly and your 4 corner cylinders could spring a leak
I don't think the valves hit the gasket, the gasket seems to go round outside the bore, and a valve can't really hit the bore, unless there's something really wierd wrong.
I would tear it down, get some hyper pistons, pop them in, have the block cleaned, honed (maybe rebored, measure it first) and surfaced, a bent head might have bent your block. Resurface the heads, too. But check, that you don't run into clearance probs.
If you need more help, here's where to get it.
But as always, that's just my way of thinking.

If you chose to just set up the heads again and pop them on, then be prepared to tear it down again soon. It might run nicely for 50k miles, but on the other hand, it probably won't.

That's all from me,
Max

Originally Posted by MadMax

Hmm... a bent head might have bent your block. Max

lmfao yeah dude take it to the professional engine straightner hell you know take it to the engine stretcher and make yourself a big block

Top of that valve in the pic will eat anything installed on it!!!!Need new valves where ever the rockers ate into it.

i dont see this multiple type of pistons maybe i'm just retarded, but i only see three different pistons from the entire engine, and they're both the same piston design...

The three pistons visible are all the same. It's just different light reflections making them look that way. I also think the engine should be torn down. Someone didn't know what they were doing when they put it together and unless you go through it now, while youve got it already partially broken down, you're going to have to do it real soon. I hate doing the same job twice. The cylinder walls do appear scratched and those pistons look really bad for such a new engine.

I used to have one of those engine stretchers, but it broke when I tried to stretch a flathead into a 392 hemi.

Art

I may be old, but. What?

Yeah, I'd disassemble and start over too. Could be the next thing that will happen is to wrap a rod around the crank

yep no# 2 could be well on it way. i have one of the hard to find block shirker yes this is the tech word for it. not stretcher that is for something totally different