Death of a piston (pics)

biggerred · Jan 17, 2015

The highdrum Super M I'm working on had some real bad blowby. Dang thing ran like a sewing machine otherwise. Broke it down today and discovered why.

87nassaublue · Jan 17, 2015

What is that stuck in the top of the piston, a fence staple?

biggerred · Jan 17, 2015

Kinda screwed up the head too.

gene bender · Jan 17, 2015

Fence staple would not get thru the valve.

biggerred · Jan 17, 2015

Here's the head.

biggerred · Jan 17, 2015

If I knew how thick that area of the head was I'd brazen up that dimple and reuse the head. I'll probably replace it.

biggerred · Jan 17, 2015

I think the dimple in the head answers the question as to what caused the problem. The thing sticking in the hole is a piece of the aluminum piston that must have got drawn in and shoved back through.

David G · Jan 17, 2015

Something got in there.

gab · Jan 17, 2015

A piece of aluminum isn't going to poke a hole in chunk of cast iron is it.

biggerred · Jan 17, 2015

Drawn back into after the fact. The hole in the head (dimple really as it doesn't go all the way through) was caused by whatever popped the head I think.

tractorguy2 · Jan 17, 2015

My guess would be a screw out of the carb. I've seen it happen many times on air cooled engines.

tractorguy2 · Jan 17, 2015

What ever it was could now be in the muffler.

Ron in Can · Jan 17, 2015

I saw one once that a ball bearing got in and did it do a number on the piston and head dimples all over the piston and the head looked like it was peined with a hammer head was saved piston was toast

rustred · Jan 18, 2015

nothing wrong with the head, just have it magnafluxed and resurface it.

87nassaublue · Jan 18, 2015

I agree. I'd also peen down the sharp edges that took hits.

notjustair · Jan 18, 2015

I used to rebuild a lot of VW engines. I was standing behind one tuning it after a carb rebuild. I rapped it out and the brass accel pump jet sucked in the engine and came right out the stinger exhaust into my shin. Apparently they were brass for good reason. Never did do anything other than put in a new jet.

cbice · Jan 18, 2015

I had the same thing happen to mySM, was caused by the tang from the spark plug!

Fatamus · Jan 19, 2015

That piston looks like I feel :shock:

Death of a piston (pics)

biggerred

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87nassaublue

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biggerred

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gene bender

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biggerred

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