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Discussion Starter #1
Just had to put a piston & cyl. in my son's 99 ZL 600 with only 3,000 miles on it .This sled has not been beaten on (it was mine till i got my F7) is this common? Iknow in 1998 they had a problem with the 600 blowing pistons& cyl's .My dealer said it looked like (coldseize?) to him we hadrun about 35 miles then stopped on the lake to watch dragraces for about 3hrs .My son started sled and let it run for 3or4 mins. and didn't horse it when he took off. Went about 1/2 mile then died . Is this common (coldseize) ?It's costing about $600. or $700 to fix it with my luck my f7 will be next .Could this be related to the 98 600 motors? and what is coldseize?
 

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Yes Select 99 ZL 600 EFI snowmobiles DID have a piston recall just like the 98 ZR 600s did. Cold seized is when the engine seizes because its not properly warmed.
 

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Blown engines are something to get used to with cats. pistons and rings should be replaced every 3000mi, its not fun to shatter a piston. I've lost count of how many engines I've blown
 

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This certainly is not unique to Cats. All brands will have similar experiences and it is part of what comes from high performance two stoke motors. I had a recent experience that had some appearence of cold seizure damage, but was the result of an air leak. I had to replace the cylinder and repair the crankcase. If you do the repair yourself you may want to take the motor in for a pressure test if you're not sure what the cause of the failure was.
 

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Cold seize is when the motor is hot and the thermostat opens letting cold coolant in cooling the jug faster than the piston.If I'm wrong let me know.
 

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You are correct as that could be one of the causes. My understanding is that a cold seizure would be any time the piston is expanding faster than the cylinder. This could be from not letting the the motor warm up properly before riding, which I believe is the most common cause. A lean burn down can also give some appearance of cold seize if it doesn't happen at wide open. The piston edge may not melt away, but the piston overheats and expands and results in heavy scoring and four corner scoring. This was my recent experience and why the original poster needs to look for water and or debris in the carbs as well as air leaks in the intake and crankcase.
 

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Has anyone heard of blown pistons because of an air lock in the cooling system? I blew the pistons yesterday on my new ZL600 SS 2003; 1600 hundred miles. My dealer said it was caused by an air lock in the cooling system.
Curious to hear if anybody else had the problem.
 

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Air in the cooling system is what Cats says is the problem with the F-7. If the cooling system fails then the piston will expand beyond it's normaly expected limits and mess up the cylinder as well as the piston. It is probably difficult to say for sure that that was what caused your problem, but the other question is how did air get into your cooling system that had been working for so long? If it was air in the system of your new sled, then dealer set up may be to blame. Did you lose both pistons, or just one?
 

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Discussion Starter #9
Got sled back today it ended up costing me $800 . He said it looked like he didn't let it run long anuff and took off running it 1/4 or 1/2 throtel he claims that is when it runs the leanes and cossis it to seize up! he said every thing else looks good lets hope so can't afford this to happen again!!!
 

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Both pistons. I usually travel at a speed of 40 to 60 mph but when the pistons burned I was doing 85 mph on a great groomed trail along a transmission line.
 

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My dad has a 00 zr 600 and it has had 2 pistons warrentied by cat becuase the ring locator pins keep poping out and taking out the piston and cylinder. Because of this, I put new wiseco pistons in my 99 zl600efi at 3500 miles. I have run this sled hard. The orignal pistons were getting wore bad right where the ring locator pin is located. Mine may have begun to work its way out since there was a scratch on the cylinder right where the ring locator pin is on one cylinder but not the other one. I am going to start putting new ringd in it every other year now since rings are a lot cheaper than cylinders and pistons. The best answer to this problem I have herd was from wiseco. They said when the rings become worn and the ring gap gets bigger, the rings rock back and forth putting too much stress on the ring locator pin cause it to break and come out.
 

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I personally dont think weisco are that good...when i had my 96 zrt 600 open mod thats what i had in it, and it seemed like every week i had to put new pistons in when i had weisco...and no there was nothing wrong with it that should have made it do that, since it was built be 3 15 year racing vetrans....so my thoughts are yes replace them but think hard about using weisco.
 

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I have had quite a bit of experience lately with ring locator pins falling out. two different engines I have worked on had the pins rock sideways and rings turn and tear up cylinder. One had only 70 miles twice after replacing pistons. Root cause was another dealer removing badly seized on clutch and knocking crank out of phase. Remachined cases, rephased and straightened crank and problem gone. A poorly maintained or out of balance clutch can also cause vibration to knock ring pins out. As for cold seizure, I had a customer with a 98 ZR 600 that I just put new pistons seize motor 40 miles after. He claimed to have warmed sled up but machine was jetted for 6000 feet and where he unloaded was at 2500 feet. Ok to take it easy until altitude reached. Piston seized 1 mile from truck. Very cold day. Warm up time should be at least 5-10 minutes and then take it easy on trail for another 5-10 minutes. Don't hold sled at midrange for extended periods when warming up or at lower altitudes than jetted for.
 

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I just bought a 94 wildcat 700 efi from a guy who said he dumped his coolant and seized the engine. when a mechanic friend of mine took the heads of and hit the one piston with a hammer gently, it broke lose and would turn over. he put it back together and sled starts and idles fine. if anyone knows what i need to worry about in terms of cylinders and crank, or can recommend what course of action should be taken to prevent further problems and $$$ would be great.
 

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I was told that snow getting in the intake can raise hell with the pistons also. I don't really know what it does but I bet that cold snow in a hot motor could maybe crack a piston skirt? When I replaced the pistons in my 700 last year they were all scored up on the bottom of the skirt right where the intake port is. One guy who looked at the old pistons said it looked like snow got into it. Very well could have been because the sled was really messed up when I got it, it was being driven with 2 busted motor mounts and all the little pins were missing that hold the rubber piece to the air box so it would have been real easy for any thing to get in there.
 
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