I purchased what im told was a rebuilt engine, with 1 season on it. I installed it, but it never ran right, wont idle, kept stalling, runs rough, wont restart. Compression was the last thing I checked, one cylinder is 120psi. I opened it up, and there is a lot of pitting on the piston and head. What would cause this. Seller said it was fine. I had used it for 30 min tops. He said I may have flushed it incorrectly, I've had like 10 seadoos and boats, I know how to flush it, but perhaps water did get in as he says. Thoughts? Other piston is fine except the head has some pitting view pictures.
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Piston pitting
- Thread starter danzr1
- Start date
That is so big/sharp marks, so nothing else than "mechanical", it is probably from a piston ring or a circlip that holds the piston-pin.
If everything now is ok ( except the "visible" marks) then that top and piston was already in that condition when engine was assembled last time...
My Guess is that a circlip have gone and messed this up, and seller have "rebuilt" it with new circlip and piston rings, and maybe "fixed" the piston-ring grooves a bit, and that have now failed so piston rings cant move freely and thats the reason to bad comp.
It should not run bad because top is a bit "spotted".
, it is just "Cosmetic issue"
But not to blame anyone, ofcourse there can be that way something have "entered" the cylinder, but it is not a "easy way" Through the carbs ( or part from carbs) but then it have to go through the reads down to the crankshaft housing, and later flushed through the "transfer ports", and finally end at the top of piston..
But readvalves or the cage ( readvalve cage/holder) can be broken.. and these parts have entered the cylinder. ( same way as just explained)
Check these, and lift out piston or try to check the pistonrings through exhaust or intake port, if You dont want to open up the engine yet. try to push on them with a small screwdriver or something and see that they "moves" in the grooves.....
If everything now is ok ( except the "visible" marks) then that top and piston was already in that condition when engine was assembled last time...
My Guess is that a circlip have gone and messed this up, and seller have "rebuilt" it with new circlip and piston rings, and maybe "fixed" the piston-ring grooves a bit, and that have now failed so piston rings cant move freely and thats the reason to bad comp.
It should not run bad because top is a bit "spotted".
, it is just "Cosmetic issue"But not to blame anyone, ofcourse there can be that way something have "entered" the cylinder, but it is not a "easy way" Through the carbs ( or part from carbs) but then it have to go through the reads down to the crankshaft housing, and later flushed through the "transfer ports", and finally end at the top of piston..
But readvalves or the cage ( readvalve cage/holder) can be broken.. and these parts have entered the cylinder. ( same way as just explained)
Check these, and lift out piston or try to check the pistonrings through exhaust or intake port, if You dont want to open up the engine yet. try to push on them with a small screwdriver or something and see that they "moves" in the grooves.....
The piston does move freely, i think the reason for the compression loss is the missing bits at the top of the piston, the ring at the top isn't sealing well anymore. Hard to see in those pics, but the pitting is down to the top ring, so more than cosmetic.
I have a new piston/ ring. I just want to know what may may have caused it, before Installing new parts.
The only time water may have gotten in was after installing the engine, it stalled when running on water for the first time. I stopped water, and started it back up. Basically this wouldn't run right, I had to turn the idle up to keep it running. This wasn't as noticeable until there was a load, ie in water. Which makes sense. I guess if I did get water in it, could this have caused this much damage? I find that hard to believe.
I have a new piston/ ring. I just want to know what may may have caused it, before Installing new parts.
The only time water may have gotten in was after installing the engine, it stalled when running on water for the first time. I stopped water, and started it back up. Basically this wouldn't run right, I had to turn the idle up to keep it running. This wasn't as noticeable until there was a load, ie in water. Which makes sense. I guess if I did get water in it, could this have caused this much damage? I find that hard to believe.
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I just took the cylinder off, it gets worse. The lower piston ring is gone. Piston gouged up one side. No way I did this. He sent the engine with carbs on premix too. I ran it.on water to check for leaks, then first timenin the water it died as soon as I left the trailer, couldn't start it after that, once warm. Now what. I paid $1850 cdn for this engine. Plus shipping. Also the mag cover was cracked during shipping, I had to buy a new one. $2500 in and it appears to be garbage.
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snozeberriestastelike
New Member
Those are what my heads looked like after the previous owner broke a piston ring and ran it until it didn't run no more. As a matter of fact I replaced everything but the chewed up head and I get close to 150 psi on both cylinders.
Sorry but you were sold a junk engine.
The lower ring let go and that is what all the damage is from.
Nothing you did caused this.
He sold you this engine knowing it was garbage because the lower ring was completely gone so he took it out. Even if it let go there would still be pieces of it in the ring groove, head and piston top.
Even worse is those are 1.00 mm over pistons so the engine has been rebuilt before and grenaded again. With the bores already being 1.00 mm over you are going to have to sleeve them or get new cylinders as you can't go bigger than 1.00 mm.
Hopefully you can get a charge back on your credit card.
The lower ring let go and that is what all the damage is from.
Nothing you did caused this.
He sold you this engine knowing it was garbage because the lower ring was completely gone so he took it out. Even if it let go there would still be pieces of it in the ring groove, head and piston top.
Even worse is those are 1.00 mm over pistons so the engine has been rebuilt before and grenaded again. With the bores already being 1.00 mm over you are going to have to sleeve them or get new cylinders as you can't go bigger than 1.00 mm.
Hopefully you can get a charge back on your credit card.
Ya, i don't think he was trying to screw me, but blaming it on water is a sign. He's not answering my calls, hasn't read my messages. Anyway, im moving on with what I got.
My plan: fill bottom end with oil or something, rotate crank, suck out and inspect for any metal shards. If clean, change piston and rings, I have a new head I can use. I have a new gasket kit. Run it ans cross my fingers! Ill also be using newly rebuilt carbs by me using Gen mikuni parts. Im worried if it did break on me, where the ring is! Also, ill lightly hone the cylinder small grooves down low, wont affect rings i dont think.
My plan: fill bottom end with oil or something, rotate crank, suck out and inspect for any metal shards. If clean, change piston and rings, I have a new head I can use. I have a new gasket kit. Run it ans cross my fingers! Ill also be using newly rebuilt carbs by me using Gen mikuni parts. Im worried if it did break on me, where the ring is! Also, ill lightly hone the cylinder small grooves down low, wont affect rings i dont think.
Well, you need to split the cases and check the crank and replace the crank seals. No way all that junk is out.
There is really no point in installing new pistons and rings of the same size, cylinders are already damaged and a quick "hone" is just going to make them more sloppy. Compression is going to be low.
Do it once and do it correctly.
There is really no point in installing new pistons and rings of the same size, cylinders are already damaged and a quick "hone" is just going to make them more sloppy. Compression is going to be low.
Do it once and do it correctly.
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