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Discussion Starter #1
Well after almost 1000 kilometers on Cody's rebuilt 600HO, it appears he cold seized it.
It was only 1 cylinder. (stator side)
The other 1 is fine.

We ordered a new jug and I'm calling Bill in the morning for another piston, ring and pin.

Here's the pics.

Please let me know what you think.

Jeff
 

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kind of hard to see, but is the top of the piston pitted? might have been running lean if only one side was damaged. I'm no expert though.
 

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Jeff, Can't you acid wash the piston remnants off that jug and reuse it ?. Looks like either ran hard cold or low oil distibution. Blow out that side supply line, observe the oil jet.To be on the safe side, replace the 2 check valves on the oil pump. Spin the pump shaft with a cordless drill and see what the volume is.
 

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I don't think it's a cold seizure. Cold seizure results in a "4-corner" seizure, with seizure marks on either side of the ports, but not usually all across the front like that.

There's a piston failure guide somewhere on the net. I'll look for it and see if I can post a link.
 

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From what I can see from the picture, it looks lean to me.
 

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I don't know about reusing the jug. Nicasil cylinders are a bit funny. Harder to hone. For sure the jug can be reused, but it might need to get replated first.

Looking at those photos again I have to wonder if it's not damage from debris. I wouldn't put it back together without checking out the crank.
 

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Do you have any chipping between the ports of the jug?? If you do, its probably best to have it renicked,,,, if not, a light new cross hatch and your set.
The top of your piston also looks really really clean,,, (from the pics) did you clean it or was it like that when you pulled it?? Mine looked like that and I had blown an o ring after the cooling line in the head came off,,, dumped antifreeze down there and pow,,,, it only hit one side also. Were you low on antifreeze?? was the head or base gasket bad,, leaking???
 

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Good call Puree.
Trailblazer, I wonder can you post a better pic of teh top of the piston? It looks to me like there was damage from debris done to the top of the piston. Certainly there was not enough carbon build up on it, so something other then cold seizure is going on there.
 

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Out of curiousity..is the ring locating pin still there?...I had a similar failure and the only thing we could find was the pin decided it had a case of the insecurities and decided to leave.
 

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Discussion Starter #13
Thanks for the quick replies guys.
Also thanks for that link NB. It was very helpful but you're right, none of it says, "Yea, that's what I found and therefore this was the cause."

The jug is definitely toast. Unless I wanted to bore it out and get it re-plated.
There's some gouges in it that can't be removed without some major boring.

Here's what I hope are better pics. As far as the jug goes, I can't get the light to shine inside the cylinder to get better pics of the inside. Sorry. The piston isn't dished. It was just wiped with a rag. It was clean like that. The other piston did have some carbon buildup but ever so slight. Keep in mind this motor has just a little over 500 miles on it. There was no sparkly star pit marks on top of the piston to indicate a lean condition. There were no marks on the top either to indicate any debris either. There are 2 spots at the bottom of the skirts where some metal has chipped away. I would guess though that it happened after the other damage had been done, I can't see how it would be the cause of all that. There are 2 pics that I cropped and hopefully you'll be able to make it out.
There was some carbon crud or ash buildup on the rave valves. Sorry I don't have any pics.
As far as the head gasket/o-ring seal goes. It was fine. Perfectly seated and nothing to indicate that any coolant got in there. The piston and jug both look like the piston expanded and scraped the aluminum off the sides and the scraped metal then damaged the sides of the piston. Yes the ring locater pin was still there.

As far as what it did at the time of losing the piston.
I wish I could tell you. I wasn't there. It's my son's sled and he was gone with some friends on an Easter Seals Fundraiser. He thinks it must have happened the one morning that it was -26C and he had some difficulty starting it. (Still getting used to the enrichment lever as opposed to the primer plunger.) Once he got it going, his buddies took off full throttle and he ran hard to catch and keep up to them on a cold motor. However, never did the sled not run or seem to have suffered any internal problems or experience a power loss. Again, keep in mind this sled wasn't really broke in yet. (250 miles at that time.At the time we tore it apart, it had only 500+ miles on it.)

For break in, I did a heat soak cycle 3 times. Started it, let it idle for about 4 to 5 minutes. Then shut it down for 4 hours. Repeat twice more. I did dump in 1 litre of Bombi mineral oil in the first tank of gas. This may have caused it to run too lean which in hindsight was too much oil and may have started doing some damage. Once he burned up a half tank of gas, he topped it up with no added oil. He did usually take it easy for a few miles or minutes to get to the trails before he ran it harder. Never letting it sit anywhere near the top end for any length of time. Nor the bottom end. He did this for the first few rides and then started running it with some full throttle pulls. I was running Bombi mineral oil in it.

TD, I will definitely check out the oil pump and follow your advice there. I'm thinking that you're going in the right direction there. Combination of run too hard, too fast with possibly not enough oil.

Here's more pics.

Thanks again guys.

Jeff
 

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the jug definetly needs renicked,,,, honing wont help you there. You also have a little more carbon on the piston than I first thought, so I would rule out the antifreeze issue,,,

If he started it, then took off to catch his buddies, I would lean towards a cold seizure,,, piston expanded faster than the jug,,,

I would also think that if you got liquid (antifreeze or water) in there, (especially water), it would have affected both sides instead of just one.
 

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Hey Jeff, Im not sure what your doing for a cylinder, but Ive delt with these guys a couple times and the service was great, a heck of a lot cheaper than a new cylinder.

They have a exchange service, they send you a new(replated) cylinder and then you send yours back, so no delays, they are worth a call in my books. They advertise $279/cyl., I can look up a bill and see what the end cost is

http://www.atelieradrienbernard.com/contenu/index_ang.cfm


Good Luck, Todd
 

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I guess that $279 is Canadian dollars. Places like Millennium Technologies have re-nic'd cylinders for $199 US with core exchange, $299 CDN. Very good deal for as good as new, IMO.
 

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When we bought our 3 new Polaris snowmobiles from two different dealerships, they all said the same thing, you want to hit various rpms during break-in. I was told never to let it idle while there was extra oil in the tank. Letting it idle, NOT revving it, and then shutting a 2-stroke off is bad news. You have to rev in order for the oil to get "spit out" or it will build up. This is not your case (duh) but I figured I'd let you know. The idea of your burn in period is to give your engine a chance to burn off the coating protecting the cyclinders from factory. Not increasint your rpms during the burn in period means the extreme ends of the cyclinder in use during high rpms doesn't get burned in. So when you finally give it a good shot off gas, problems may occur. The idea during your break in is to hit ALL rpms, but don't hold it bar tight for too long, as until that coating is worn off it might heat up faster than normal, and conk yer engine out.

I dunno, I might be wrong there. But all the Polaris dealerships I ask have all said the same things about burn in, as did two other mechanics I talked to. It's important to hit various rpms during break in, without running the engine hard.
 

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For break-in I run it as hard as I can. Get the thing under load and put some pressure on those rings. Apart from getting the rings to seat properly and giving you the most horsepower, I want to find out if there's an assembly issue in the first few minutes.
 

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Jeff,
something came to mind today when I was diagnosing a high idle on an 03 MXZ (ZX). There was a cap blown off the lower crankcase nipple on this 700 (type 693) which caused fast idle hot and the piston was starting to score.
 

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Looked like some debri damage there to me also, hes right, check for more damage lower if only to be on the safe side. Wouldnt want to starter up the first time with a new jug and klank klank boom.
 
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