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1996 Polaris xlt 600. 1992 arctic cat ext 550
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Discussion Starter #1
I’m new here but I’ve been around sleds along time. I’ve got 2 sleds that have me stumped and would like some ideas or maybe things I over looked before I tear into them, so sorry but this might be a book!
1996 Polaris xlt 600 triple, I traded a blown up 440 for it and when I checked it out, it had 120 psi in all cyl. The choke was broke so he would spray alittle gas into the cyl. And it ran great. Got it home ordered the new choke lever, topped off oil and just a basic service. Got some snow and it ran great for 5min and fell on its face. So I took it to a guy that adjusted the carbs and cleaned them. Said the middle carb had a sticky float and that the choke cables were basically always engaged and the throttle was backed all the way out so he fixed that. Rode it again for about 10min without issues but was hard to start after it was warm. This past weekend we went to Michigan to ride for the last time this year and it ran great for about 15miles and my temp light came on. My left radiator was cold the right was hot and the front was hot, I figured an air bubble so I found a snow bank and let it idle and kept adding fluid for about 15min everything seemed good, started heading for the truck and 5miles it did it again now a ton of air again, towed it back to the trailer and went to the hotel. I let it run for 45min in the trailer with it tilted up and adding coolant as needed (maybe a quart in all) no air moving under the sled and also no temp light. I thought i just didn’t get all the air out on the trails. Went back and damn in 5miles I was back at it over heating. It seems as if the cooling system is being pressurized? Headgasket maybe? No signs of coolant in the exhaust, no leaking hoses, water pump belt is tight and there is a noticeable flow. Got home today and checked the compression I have 110psi across the board. I don’t have much in this sled but I wanted to long track it and we’ll if it needs a motor rebuild it’s not worth it to me lol. After riding a rental I want a newer sled if I can afford it.

Next issue is my arctic cat 550 it’s been a beast for 2 years. I have the carbs cleaned in the fall every year no issues. My buddy put 68 miles on it this weekend and then it acted like it has no power to even move itself. New plugs didn’t help. It has 119 clutch side and 118 in the other side for psi. Smokes heavily but it’s a grayish black smoke. Thinking carb related?
 

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First thing I would look at on the XLT would be the water pump/water pump belt, just to rule out a bad pump or broken belt. If you start it cold and let it run for a minute or so and have already got a lot of pressure in the coolant system, it is probably a leak on one of the head O rings or maybe a base gasket leak. You can replace those O rings without removing the engine and that won't be too expensive. You should also buy the three O rings that go around the spark plugs and the water jacket O ring as well... reusing O rings has not been very successful in my experience.

On the 550, are both cylinders getting hot? Do you have spark on both plugs? If not, sometimes unscrewing the plug boot from the wire and snipping off a bit of the wire and reattaching the boot will help that. Make sure the screw in the boot is clean and bright. If one cylinder is cold, and you have spark in both plugs, try moving the carbs side to side. Does the problem follow the carb? If so, you may have to re-clean that carb (or both, just to rule that out.) If it doesn't follow the carb, look in the intake and pull the exhaust Y pipe and look in the exhaust for damage to the piston skirts and cylinder walls.

Welcome to the forum!
 

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1996 Polaris xlt 600. 1992 arctic cat ext 550
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Discussion Starter #3
Yea the water pump and belt are good it seems I removed the cover belt was tight and everything was spinning. I then removed the belt and spun the pump by hand and didn’t notice any bearing noises. It has 110psi so instead of just doing headgaskets I was thinking of rebuilding it also ? Is it worth it ? Also has one messed with removing the running board coolers and adding a tunnel cooler? I’m going to install slp extensions for a 121 to a 136 and figured I would have room to add a tunnel cooler since it’s mainly groomed trail ridden.

the arctic cat has spark on both cylinders and both get to temp. But the plugs are excessively wet after shutting it down.
 

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When you added coolant, did you elevate the front to get any air to come to the highest point in the system? I have seen the nut that goes on water pump impeller loosen. As BC Dan mentioned you might have a head gasket problem. The 96 should have a head gasket rather than o-rings on the head. Leaking water jacket o-rings around spark plugs should be evident with coolant leaking around the plugs.
Are you seeing any coolant showing up on the snow, shop floor, trailer deck or white smoke from exhaust with anti-freeze smell?
Concerning removing running board coolers and installing the tunnel coolers: The machines that used the 2 tunnel coolers had a channel for the hoses in the seat bottom. I'm not sure if your 96 seat bottom would have that. There are some inside full length tunnel coolers but they may cause a clearance issue with the track, particularly if you extend the suspension and add a more aggressive track.
 

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1996 Polaris xlt 600. 1992 arctic cat ext 550
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Discussion Starter #5
Yea when it happened on the trail I found a bank to add coolant and bleed the air then after about 10min I headed back to the trailer, went to the hotel and then tilted the trailer and added coolant and let it idle for 45min on the tilted up trailer. It seemed as tho the higher the rpms the more air was in the system so I’m going with a headgasket now, but since the snow is done here in Indiana I won’t mess with it until mid summer. Personal preference ik but with 110psi in all cylinders would you spend the time and money rebuilding it or wait?

as far as the coolers I have the xtra 12 under it and just going with rain extensions and will be running a 1inch track, I was thinking as long as I keep up on rebuilding the fox shocks I should be fine if it installed a radiator in the tunnel extension. I’m not worried about if the tunnel is grooved for the lines or not because I wanna do a seat swap also but I’m not sure what will fit and still look decent vs a hack job.
 

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With 110 psi on all cylinders, that would indicate to me that there is some wear but it isn't excessive. However, if you recently tested it and it was 120, that would indicate accelerated wear. That would concern me. An engine shouldn't drop 10psi in a short season under normal wear conditions.

Once you have drained the coolant and removed the head, it wouldn't take that much more effort to pull the monoblock to check for damage and out of round cylinders. If I had it that far apart, I would replace the pistons/rings. If you go that route, you should de-glaze the cylinders as well.
 
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