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Cooling systems

Y

Yupper

New Member
Messages
2
Age
60
Location
Marquette
Country
USA
Years Snowmobiling
30
Snowmobile
Looking to buy
A friend of mine has a 17 Pro RMK 600. He keeps having overheat issues riding in the U.P. The outdoor temps have obviously been warmer than normal but even with adequate soft off trail snow up in the tunnel he is having heat issues. When we stopped for a break today there was substantial steam rolling out from under the tunnel. The over temp light did not come on this time but has in the past where we have to stop and let it cool. It becomes quite annoying.
Is this typical of a Polaris mountain sled and how it’s cooling system functions? No one else’s sled (trail types) was having issues.
Are trail sleds cooling systems designed differently?
 
Yes, very much so.
Its called a Rocky Mountain King and not a UPer Special for a reason, because thats where it belongs, especially a PRO. It needs a ton of powder blowing around to cool off that tunnel.
Most RMK's, including his PRO, only have heat exchangers running the length of the tunnel to save weight. All the trail & crossover sleds also have a heat exchanger across the front of the tunnel that the track dumps snow onto which does a majority of the cooling. That thing will rarely be happy in the snow conditions you get where you are trying to use it.
He should've bought a SKS if he really needed a mountain chassis since that has the additional cooling.
 
Thanks for the informed reply, I appreciate it.
 
Tell him to blow that thing out before he cooks the motor continually running it that hot.
Get into a SKS or Assault, the only real difference is the front suspension. The SKS has the narrower mountain setup and the Assault has the standard trail setup.
 
Took my new 2023 RMK 850 Matryx/Slash 165 out for the first time a couple days ago. In tahoe started at 6200’ 25 deg, left our cabin for a 1 mile ride on a patchy snow covered road to the snow. Had the scratcher up till we hit the snow, then put them down. There began a climb through the trees on and off other tracks with good fluff to go in and out of. 10 min in the overheat light came on and then shortly it shut down. Cooled it down and continued for 1hr 1/2 with some breaks with out the light coming on. Then on a pretty steep long hill climb 3/4 of the way up it shut down again. Let cool, off we go. Mostly flat or downhill riding from there for another 1Hr 1/2 back to the road home. At the road light came on and shut down again. Now oat 33 deg, The one mile road back took me 30mins as each time I let it cool then fire it up I could only go about 100 yards before cooling it down again. I then was in a rush to get home in Sacramento and sled stays in Tahoe. My thoughts…. Burp coolant tank and confirm cap is securely tight, add an aftermarket larger rear snow flap.
 
The Matryx chassis RMK sleds have a completely redesigned cooling system from the AXYS sleds with the coolers more centrally located towards the front of the tunnel & the front bulkhead cooler now so they could do the 'slash' tunnel cut. Its going to act completely different from the sled he is talking about which has much less cooling capacity.
 
850Switchback said:
The Matryx chassis RMK sleds have a completely redesigned cooling system from the AXYS sleds with the coolers more centrally located towards the front of the tunnel & the front bulkhead cooler now so they could do the 'slash' tunnel cut. Its going to act completely different from the sled he is talking about which has much less cooling capacity.
Click to expand...
So what’s the fix?……talked to dealer today who says they’ve been having some issues with the thermostats which now is part of the coolant bottle. Ordered me a new one so we’ll see if that ends up fixing the problem. I also think the very short snow flap is a factor.
 
Sorry, read that quickly earlier and thought you were responding to the OPs situation.
What was the coolest engine temp you saw during the day once you hit snow?
I hate to say it but I think the shorter slash tunnel & flap may not have been a good choice considering you have to travel a mile of very marginal conditions to get to snow. Scratchers are not going to help much in that situation either since you don't have much flap there to catch it & help throw it up into the tunnel. The shorter tunnel just augments that problem too.
Even trail sleds with long flaps take a while to cool down after that much roading.
I have heard of possible t'stat issues with some of the newest Matryx sleds, but I have my doubts thats the actual problem.
 
850Switchback said:
Sorry, read that quickly earlier and thought you were responding to the OPs situation.
What was the coolest engine temp you saw during the day once you hit snow?
I hate to say it but I think the shorter slash tunnel & flap may not have been a good choice considering you have to travel a mile of very marginal conditions to get to snow. Scratchers are not going to help much in that situation either since you don't have much flap there to catch it & help throw it up into the tunnel. The shorter tunnel just augments that problem too.
Even trail sleds with long flaps take a while to cool down after that much roading.
I have heard of possible t'stat issues with some of the newest Matryx sleds, but I have my doubts thats the actual problem.
Click to expand...
Honestly, being the first time on the new sled I never switched over the display to eng temp I have talked to the dealer and they are pretty sure it’s a bad thermostat. They ordered the part (thermostat is now built into the coolant reservoir) and will install next week. I can’t imagine this is a bad design by polaris with all their on snow testing. Hope I’m right!
 
Rscherms said:
Honestly, being the first time on the new sled I never switched over the display to eng temp I have talked to the dealer and they are pretty sure it’s a bad thermostat. They ordered the part (thermostat is now built into the coolant reservoir) and will install next week. I can’t imagine this is a bad design by polaris with all their on snow testing. Hope I’m right!
Click to expand...

Hey, not sure how this worked out, but I found they make a full length snowflap for your machine in the accessory catalog. See the link.

K-SNOW FLAP W/PLATE [INCL. SNOWFLAP,10,11,20], Part 2208364 | Polaris Snowmobiles

K-SNOW FLAP W/PLATE [INCL. SNOWFLAP,10,11,20] is a snow flap kit that includes all parts needed to assemble the snow flap to the vehicle. Designed and tested by Pola.
www.polaris.com www.polaris.com
 
On second look it may only be for the RMK Khaos, not the slash tunnel.
 
850Switchback said:
Hey, not sure how this worked out, but I found they make a full length snowflap for your machine in the accessory catalog. See the link.

K-SNOW FLAP W/PLATE [INCL. SNOWFLAP,10,11,20], Part 2208364 | Polaris Snowmobiles

K-SNOW FLAP W/PLATE [INCL. SNOWFLAP,10,11,20] is a snow flap kit that includes all parts needed to assemble the snow flap to the vehicle. Designed and tested by Pola.
www.polaris.com www.polaris.com
Click to expand...
Thanks for the reply! After getting the sled back from dealer who swapped out the thermostat the next ride was uneventful as far as no overheating. I did purchase an aftermarket snow flap…just incase. Plan to install before next ride. I bought on eBay, simple install. It’s made for the matryx slash…. So it mounts under the tunnel and you can deploy it my pulling it out from underneath the tunnel for packed snow, and push back in when your in pow.
FYI, The link you sent me is not compatible with a 23 matryx 850 pro slash. But thanks much appreciated!,
 
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