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Rocker arm failure on track

Old 11-07-2018, 11:39 AM
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Originally Posted by s2000Junky View Post
Right, which makes me think your bottom end let go first. You got a motor that cant turn more then 90 degrees. You have a piston that became separated and wedged up against the head crushing the plug and valves on that cylinder. All your valves are in place, none dropped. But if you have a piston sperate from the wrist pin, now its out of time with the valavtrain and wham! Hits the valve when its in the down/open position forcing the valve back up against the rocker wile its trying to go down, not up.That's my theory. Not sure what else it could more likely be.
Well I should have the head off this weekend, so we shall see!
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Old 11-07-2018, 12:48 PM
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The same thing happened to one of our s2000s on track, we did drop a valve though and motor the was seized afterwards. Pull the header to see if there is any visible damage to the exhaust valves. Either way, time for a new motor
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Old 11-07-2018, 07:18 PM
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Minus the last clip, getting the intake manifold off was further along than expected, so I pulled the head tonight. Here's the carnage. Looks to me like metal shards skipped across the head gasket. Note the coolant on the bench. Still not sure what happened, but safe to say the entire head and block is done for. Going to send pics to inline pro just to be sure, but the scoring on the walls seems deep enough to warrant a straight swap. Donor car lined up whenever it goes to auction:



















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Old 11-07-2018, 07:48 PM
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Metal shards through the intake manifold.

Wow, that looks terrible.
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Old 11-07-2018, 08:00 PM
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That's one of the ugliest failures i've seen, wow! So is that piston still attached to the rod? If so, it looks like the valve would have had to break and cause the havoc, rolling around in the combustion chamber. Its quite embedded in there!
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Old 11-08-2018, 09:43 AM
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I'm devouring this thread with morbid fascination and hoping it never happens to me. RIP F20C. I know nothing about building an engine, but could the block be saved if it was sleeved?
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Old 11-10-2018, 09:31 PM
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Originally Posted by s2000Junky View Post
That's one of the ugliest failures i've seen, wow! So is that piston still attached to the rod? If so, it looks like the valve would have had to break and cause the havoc, rolling around in the combustion chamber. Its quite embedded in there!
That is frequently the damage from a dropped valve. The broken off valve head hammers away at the piston, head, and other valves. Aluminum broken loose flows through the intake to other cylinders. It stops when either the engine is shut off or the piston breaks apart and the rod goes through the side of the block.

What surprises me as that all the aftermarket rockers are solid VTEC-killers yet some more aggressive aftermarket VTEC cams require a rocker arm modification. I would have thought there are enough street driven VTEC engines to create a demand for stronger, lighter aftermarket VTEC rockers.
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Old 11-10-2018, 10:55 PM
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Originally Posted by DavidNJ View Post
That is frequently the damage from a dropped valve. The broken off valve head hammers away at the piston, head, and other valves. Aluminum broken loose flows through the intake to other cylinders. It stops when either the engine is shut off or the piston breaks apart and the rod goes through the side of the block.

What surprises me as that all the aftermarket rockers are solid VTEC-killers yet some more aggressive aftermarket VTEC cams require a rocker arm modification. I would have thought there are enough street driven VTEC engines to create a demand for stronger, lighter aftermarket VTEC rockers.
It cant be a dropped valve because all the stems are still attached to the keepers on the failed cylinder. Now if the valve decided to break in half with the stem remaining i guess that would do it, but is that a reasonable failure? How would that even happen?

Last edited by s2000Junky; 11-10-2018 at 10:58 PM.
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Old 11-11-2018, 09:33 AM
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That would happen if you tag a valve enough to put a slight bend in it, the valve fatigues as the head gets hammered into the seat at an incorrect angle, and eventually the valve head separates from the stem.
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Old 11-11-2018, 11:31 AM
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Originally Posted by Chibo View Post
That would happen if you tag a valve enough to put a slight bend in it, the valve fatigues as the head gets hammered into the seat at an incorrect angle, and eventually the valve head separates from the stem.
That would be valve float. The failure happened at 7500 rpm. Do we even get valve float at stock rpm on this engine? Seems again unlikely. Mechanical over rev one too many times in the engines history, maybe? But I think the OP stated that didn't occur under his watch and motor only has 30k on it.
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