Dear Ralph:

I’ve got a 2002 Yamaha SX Viper and I threw the chain on it last winter. It wasn’t pretty, and I was shocked that it happened. Do you think the chain or gears were bad, or was it simply a matter of ignorance (I had tensioned the chain back when it had about 1,000 miles on it, but not since then).

Danny Wussem
Duluth, MN

That’s a bummer when you throw a chain. Usually it takes out the chaincase as well, and you will be getting a tow back to the trailer. I’ve only had it happen a couple of times over the years. One of them was on a Polaris Ultra, about 60-70 miles from the nearest anything, and yes, we had to tow it all the way back. That was on the first day of a week long ride, so I had to rent an Indy 500 to complete the ride that week.

Generally, drive chain failure and gear damage is due to improper chain tension and lack of maintenance. There will be cases with modified sleds where the power being applied exceeds the load capacity of the chain for a given width and design, but in your case it is pretty much a matter of a lack of maintenance. Add to this the loads applied if your track is spinning and then catches something and SNAP, something has to give. Especially on a sled that is studded.

Studies show that over one half of drive chain failures occur after 1,000 miles, so this tells us it is a matter of maintenance and not weak or defective chains. As indicated in most every service and owner’s manual I’ve ever examined, the chaincase oil should be changed at least once per season, ideally at the end of the season. Don’t just drain the oil through the drain plug and pour in the new, you should remove the silencer and chaincase cover to visually and physically inspect the chain and gears. Look for damaged link plates and/or excessive wear on the gear teeth. Each chain also has a wear limit as for stretching, this should also be measured if the chain has high miles on it.

But you and I know it was more a matter of chain tension than anything else. Sure, the chain might stretch more with no lube changes, but flat out ignoring the chain tension and letting it slap around in there is going to catch up with you. Most service and owner’s manuals are going to detail this procedure for you, but the rule of thumb is to finger tighten the tensioner and secure the lock nut. Some riders will even back the adjuster off just ever so slightly after reaching finger-tight so as to not place undue stress on the bearings, which occurs if the chain is too tight. You want a small amount of slack in there, not too tight, but not loose by any means.

Always inspect the cover gasket when putting it all back together, and clean the sealing surfaces of the gasket and the matching surface on the chaincase. Make sure the gasket isn’t pinched or folded, or you will be fighting a leak. Add the specified amount of chaincase oil and do it again next season, or after the next 2,000 miles. I like to check the chain adjuster tension after 1,000 miles of hard riding.

Dear Ralph:

I own a 2009 Ski-Doo MXZ Renegade. I’ve had what seems to be a continuous problem with the antifreeze level and leaking since my first ride. The leaking was due to the hose clamps on the heat exchanger and bottle. This was taken care of by the dealer, but I found that they only replaced some of this style of clamps that was leaking. When confronted, they said that they changed clamps as per Ski-Doo. The dealer also informed me to only fill the antifreeze bottle level to the seam (when machine is cold) because  if you fill to the cold line it will dump out of the over flow when the sled gets warm. The only problem is if you fill to the seam and run the machine and let cool down the bottle shows no coolant. When you burp the cap the coolant level rises to the seam. The dealer asked  the factory and they said this was normal. Any suggestions before my sled goes out of warranty?

Ken Kradle
Eagan, MN

You should be fine, here’s why. Ski-Doo did produce a service bulletin for their dealers last spring explaining how to pressure test the cooling system and about the clamps that might need to be replaced.

Why not replace all of this style of clamp? On the 2009 models Ski-Doo changed suppliers of some of the coolant hoses and they varied on the outside diameter. Because of this variation, the “Oetiker” clamps used on the assembly line (because they are fool/idiot proof) did not always seal correctly. To remedy this, more familiar gear-style hose clamps were used by the dealer to compensate for and seal the slightly smaller hoses.

So, some of these newer hoses that are smaller on the O.D. may leak. The other hoses that were not changed to the new supplier have had no leakage issues. Your dealer was correct in that not all of the Oetiker clamps need to be replaced. On those that were changed, gear-style clamps were used for the dealer fix.

For 2010, the sleds have hoses with very specific specifications for both the inside diameter and outside diameter. Problem solved.
As for how far to fill the coolant bottle; if you fill it too much it will purge itself to it’s own level.  It is an expansion/ overflow bottle.  If you choose to fill it to the seam or the cold line is really your prerogative. The seam will be fine, and when there is
pressure in the system you might not see the coolant.

Remember, as the system cools down the pressure drops and the coolant comes back up.  This is an indication there is a small amount of air in the cooling system.  It won’t hurt anything. As long as the coolant isn’t leaking anymore, drive the sled, have fun and stop worrying. I am confident your problems are resolved.