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What happened to this piston?

Not my engine, but I toor down a 2.7CIS engine because of a bad leak down and found this.
I see all pistons have hit the exhaust valve, but cyl1 has taken some more beating.
What happened to that?



Old 01-02-2018, 12:19 AM
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Looks like the engine already had a previous failure like a broken valve...
There are some grinding marks on the crown of the piston, I would guess a quick rebuild changing one head and smoothing the dents on the piston...
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Old 01-02-2018, 01:37 AM
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Looks like it jumped time after a tensioned collapsed, bending valves and breaking rockers.
Not enough damage for a broken valve, maybe just a chip on the face after bending
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Old 01-02-2018, 02:14 AM
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The engine was running so all valves are intact, same with rockers, but similar marks in the cyl1 head.
Would a over rev make the exhaust valves hit before intakes?

But a broken valve and a quick rebuild sounds plausible
Old 01-02-2018, 02:18 PM
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Have it been rebuilt previously and had the case align bored?
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Old 01-02-2018, 02:34 PM
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Where was the leakage when you did the leakdown? Exhaust? Then the valves were recently bent.

It is also possible that something got down the intake like a nut or washer, who knows when. What does that cylinder wall look like?
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Old 01-02-2018, 04:16 PM
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definitely had some serious hits with the valves... Wouldn't be surprised if a piece of the valve broke off and got chewed on by the piston head.
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Old 01-04-2018, 07:08 AM
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