Holed piston! Could this be the cause?

[alanscottj]

Whilst having a ride down the duel carriageway my engine went pop! Anyhow, opened her up and there isn't any other damage than the hole so gonna order a new piston later today. Obviously I want to isolate the cause. Engine (muggy 198) was dynoed and set up proper. What I found was when I took engine out there was a small wrapper/clear bag lodged in the flywheel. Could this have upset air flow enough to cause the holed piston? It was a significant size about the size of bag, like a crisp packet but all scrunched up.

[onthelam]

The only time it happened to me I put it down to the wrong spark plug. If the hole is adjacent to the plug.

[alanscottj]

The only time it happened to me I put it down to the wrong spark plug. If the hole is adjacent to the plug.

The little hole is at the tip of the plug But, I'm thinking the bag in the flywheel is the culprit......

[bristolmod]

if you've got a holed piston then it is very likely you have molten alloy somewhere below the piston- check your crankshaft and bearing very carefully.

Chris

[alanscottj]

if you've got a holed piston then it is very likely you have molten alloy somewhere below the piston- check your crankshaft and bearing very carefully.

Chris

Cheers Chris, I'll be sure to give it a good looking over before putting her back together, have got to order a new piston yet anyway so have time

[alanscottj]

This is what I found in the fly wheel, looks like cling film



I also think I filled up with different fuel to my normal unleaded, I used the 95 octane one, would that run hotter?

[dave411]

Hmm,I have read on here about Pistons being holed after fuel stops.Dont think anyone determined the cause though

[alanscottj]

Hmm,I have read on here about Pistons being holed after fuel stops.Dont think anyone determined the cause though

It was about 5 minutes after filling up, if that

[bristolmod]

I think the cling film or whatever is co-incidental.

I'd be looking for other causes.

Chris

[Donnie]

Certainly likely you were running lean for some reason if it's a holed piston, if you don't remove the crank to check all the bearings and replace your seals your asking for more trouble down the line? also, how many miles since it was built did this happen?