what could cause this???

[NATEO]

its my 82 GS750e. any ideas what could cause the piston to melt? I have a new top end to put on, but I want to make sure its not just going to melt another piston...

also, provided I use the matching block, can I swap pistons from my parts engine? or is that going to require more work than just swapping parts?

Thanks

[focus frenzy]

dang!! that is bad!!
you are not suppose to ride it till it quits!

that looks like detonation failure, could also be from a fault in the piston.
generally a lean condition failure happens in the center of a piston where they are the thinest.

[first timer]

to much ether? wow that doesn't look good. what do the other three look like? i would be concered that other parts are bad like ol pump getting metal in it, maybe even getting chunks in the bearings to. If it was me i would see about finding a new motor and strip this for parts.

[NATEO]

to much ether? wow that doesn't look good. what do the other three look like? i would be concered that other parts are bad like ol pump getting metal in it, maybe even getting chunks in the bearings to. If it was me i would see about finding a new motor and strip this for parts.

the other 3 look fine, and except for the obvious wear on the cylinder wall, it doesnt look like there are any particles anywhere under the piston... the engine I am getting the head/block/pistons from is pretty much junk... it is missing a bunch of stuff, and while I know I could take parts off the blown engine, this parts one is in really tough shape...


if I were to go against all recommendations (I have been known to do that... see where it got me?) would swapping pistons require rehoning and new rings? or would using the matching block prevent that?

[focus frenzy]

if I were to go against all recommendations (I have been known to do that... see where it got me?) would swapping pistons require rehoning and new rings? or would using the matching block prevent that?

well if the pistons and rings from the "parts" engine are good, then you should be fine. you might want to do a light hone but it is more important to use all 4 pistons and the cylinder block (make sure to put in same order) as the donor pistons will be worn in to that blocks cylinder.

[mark]

Assuming your crankshaft is O.K., swapping pistons is possible in another bock as far as I know. Both pistons and block are easy enough to measure for proper spec. and piston/wall clearance.

You'll need new wrist pins and circlips. Rings as well, make sure to measure for proper gap. Cylinder honing is required.

Take a good look at your connecting rods where the wrist pins go and check for any abnormal wear, that piston took a beating. That can be measured as well.

Sure wonder what happened. That's nasty.

[chef1366]

Holy sh!t Batman! Looks like it got dropped into molten lava!

[smagnusen]

make sure to save that as a nice souvenir - would be interested to know what caused that myself

[salty_monk]

Looks like two I've seen before on cars.....

One was a 4cyl VW Rabbit that had been driven till it stopped with no oil in it.

One was a Blown chevy corvette drag car that had a fuelling problem & ran super lean & bang.....

Could have been either or a bit of both....

Dan

[earlfor]

Usually, a lean mixture or timing too advanced causing preignition will burn a hole in the top center of the piston. My best guess, is no oil flow, or blocked oil supply, oil pump problem.

Earl


[quote=NATEO
any ideas what could cause the piston to melt? I have a new top end to put on, but I want to make sure its not just going to melt another piston...

[first timer]

like earl said, before you put this thing back together, check your entire oil system from screen in oil pan to the passages up into the head and the oil pump too. The PO may have gotten a piece of RTV stuck in i passage somewhere and burned up a piston.

[NATEO]

like earl said, before you put this thing back together, check your entire oil system from screen in oil pan to the passages up into the head and the oil pump too. The PO may have gotten a piece of RTV stuck in i passage somewhere and burned up a piston.

ok, I will check the passages, screen and pump before I put stuff back on...

am I going to see major issues if I just swap parts without honing and new rings? I can still see the pattern from the last time it was honed. of course I will check rings when I get the block off....

[focus frenzy]

if the cylinders on the donor engine check good, (IE: it had a fresh rebuild or was low miles before retirement) then you should be perfectly fine.

you will need to make sure to use all 4 pistons in the same order they came from the donor engine, as well as the cylinder block.

[NATEO]

if the cylinders on the donor engine check good, (IE: it had a fresh rebuild or was low miles before retirement) then you should be perfectly fine.

you will need to make sure to use all 4 pistons in the same order they came from the donor engine, as well as the cylinder block.

ok, thanks... looks like I will be digging into my engine even more tonight!

[SqDancerLynn1]

I would use the matching block, remove the oil pan & check the oil pickup for derbs. While your at it remove the clutch & replace the O rings on the oil pump