M1000 piston failure!!!!

[THINairJUNKIE]

Its on a 07 m1000. Pto side piston. Ring gland is broke or worn off on top ring. Ring walked around and broke off in exhaust port. Mag side wouldnt have made it but a few more rides. Gland is also gone in it. Top rings only no problems with bottom ones. Sled only has 1500 mi on it. Anybody else had this problem? Think cat will stand behind it?

 

[THINairJUNKIE]

Nobody else had problems?

 

[CATSLEDMAN1]

ring land

upper ring lands most often fail from two issues, intermittented detonation that weakens the aluminum and aneals the piston crown, then upper ring trying to weld itself to the cyl ........and on each down stroke that top ring land is pulling the ring down and when the ring sticks harder to the cyl wall than the weakened strength of the softening aluminum above the ring, out pops some aluminum above the ring and each stoke thereafter is a downhill disaster. As the piston aneals the ring land clearance increases making it harder and harder for the ring to transfer the heat into the cylinder wall leaving the piston hotter and hotter........case of everthing going to heck in a hurry.

starts with too much heat for your piston to handle, and ends with piston /ring/locating pin... one or all givingup the ghost. Was the case 40 years ago and nothing has changed. Gotta figure out why your 1000 was to hot to start with ??? Or failure to cure the problem will result in same engine failure over and over and over.

 

[THINairJUNKIE]

When it went the sled had been under half throttle for probably 20 min or better coming down a creek. I had just burpted the throttle over a hole when i felt it go i shut it down imediatly egts were at 800. Piston wash and plugs have been dead on for some time now. Could this be a prolonged symtom from several rides before? How do i find the intermittented detonation? The piston never stuck. Theres no definate sign of heat any were in the break on the piston, rings or cylinder.

 

[smoothdawg]

Could it have something to do with running nitrous with too low of an octane?

 

[THINairJUNKIE]

Been runing the nitrous since it was a couple months old. Also run 30% 110.

 

[CATSLEDMAN1]

More late model engines over heat and have lean spots in low mid range than top end, bad fuel maps, wondering timing right in the low mid transition area, poor clutching which will give you a throttle postion sensor signals that are out of whack.
When reading piston wash good and no lean spots means a bright clear aluminum piston where its washing, you almost will never see that with current fuel injection sleds because they all seem to have lean spots in their fuel maps......and that lean spot lays down a brown coating over the washed piston area and then you wash it again when the sled is running rich mode and you get the funky indistinct not really what you want piston wash. Keep in mind piston wash is a check that was developed with gas leaking carbs, and pressure atomizing fuel injection won't give the same wash.

Low egt's 800 degrees? 800 degrees can be too hot for low mid fast ground speed low throttle opening? Any way, piston got too hot. A post mentions nitrous? Who knows what that 20 seconds of nitrous is doing. Instant cold on a white hot piston could be destructive.

Signs of heat: underside of piston crown with brown on it or black carbon? wrist pin discolor, streaking marks on cyl of not blown up jug, no brown soot in y pipe / whiteish color.......or have piston checked for hardness at truck engine lab, you'll find it soft.

 

[M Turbo]

Poor fuel !!!!!!! Ring gland only falls out when detination occurs!!!!

 

[THINairJUNKIE]

I have checked for all the signs of heat you list and none of them match. After looking at the lands closure they look like they have rubbed off. The ring has rub marks on the corners were it contacts land. I had some other guys look and they cant find any signs of heat either. Talking to some turbo guys and they have had alot of them do them same and have changed to wiseco and had no more problems. As for nitrous the sled has never had more then 5 to 6 sec at a time.

 

[Killerk]

Think cat will stand behind it?

After reading your sig and other posts I hope you are joking!^^^

 

[dogtownbutcher]

i had a piston skirt break of on the mag side, which lead to a hole in the case! A buddy of mine said it looked like it detonated on the top of the piston!

 

[mrquick68]

i had a piston skirt break of on the mag side, which lead to a hole in the case! A buddy of mine said it looked like it detonated on the top of the piston!

here's just a guess. if you had an aggressive port job or at least one with the top of your exhaust port too squared off, that in conjunction with NOS and running that motor hard, you will start to over stress the rings, especially the top ring where it can start catching on the port.

just a thought.

 

[CATSLEDMAN1]

hot motor

good fuel, rich fuel conditions, lazy running and insufficient cooling will still cause piston failure, that's why all the engine manufactures have decide that prolonged engine coolant temps above 135 dgrees in a two stroke aluminum snowmobile engine will lead to collapse of the engine....sooner or later.

So.... well.......melted hyfax ? coolant leak? charred head o rings ? disconnected oil cable ? temp light on? do you have a real temp gauge on the sled ? lots of hard snow trail riding ?

Just rebuilt a cat engine for a cabin owner that wouldn't keep his sled off the lake, just couldn't get it through his noggin that hard snow, 2.5" track, blue ice with scratchers down, and doing it over a period of years wouldn't finally ruin his motor......and it did.

His head o rings where hard as a rock and broken, his thermostat was stuck wide open, his oil lines had been so hot so many times they were shrunk down to half their carrrying capacity, no hyfax on the back of the rails and some track clips wore through, both carb boots were brittle and toast, sled looked new, water pump seals were rock hard and leaking, had 1500 miles on it, and only ridden at 1/3 throttle accross the lake to get the morning paper.....many times.