Another overheating problem...

[ewald]

Hi everyone. After I installed the 365x38x44 the machine overheat a lot. I can't really say it's because of the track, swapped almost directly after the purchase. I also geared down one tooth on the smallest and that is of course not helping the problem. My riding style is pretty slow, often under 15 km/h with a lot of weight on it and sometimes double passenger sleigh behind. Where I live the trails are going over steep hills, bridges and more, so the machine has to work pretty hard. But with a big family and bumpy trails, crawling uphill is the way to go for us. The engine overheat regardless to snow condition or outside temperature.

I have adjusted the coolant (didn't changed it) and measured the freezing point. Added water wetter and mounted a set of cable scratchers under the engine. Helps a little.

Now to my questions.
It's seems like the rad is covered with too much of the side panel. Wouldn't the airflow increase over the rad if I cut a piece out. I can even mount something to stop the snow spray from filling up the exposed part of the radiator, but lets the air in. Any one tried this?
Just before I went home from my cabin I checked the fan if it was spinning and yes I did. But the fan seemed to run the wrong way, pushing air against the airflow, if you see what I mean. Is it so? Or is the fan sucking the air trough the rad an back?

 

[ewald]

 

[Mooseman]

Cutting out that panel may help a little but the real problem is the speed you're running at. At that speed, only the radiator and fan are mostly cooling the engine. Unless running in deep loose snow, not enough snow will get flung onto the front tunnel heat exchanger. And at that speed, you're not creating a lot of air movement through the radiator. You would need a shroud to help the fan pull air across the entire radiator.

When the light does come one, you're not actually overheating yet. Just stop and let the fan cool it back down.

You're running at the speed where you're making enough heat but not moving enough to cool it.

 

[YukonMP]

I wouldn't worry about snow on the rad until experience showed it was a problem. When I am running in marginal conditions I pack the rad with ice shavings from my fishing holes.

It does sound to me as if your fan is running backwards. To fix that you might just rewire it to a switch and just run it steady after warm up.

I agree with Mooseman in that you likely aren't getting enough snow kicked up on to the heat exchanger. I run those speeds on the trail down to the lake but only for a mile and lightly loaded. When I am on longer runs we usually manage 20 km/hr and I'm OK.

I didn't quite get what you were saying about your track. Did you switch to a higher lug? If you have I would guess that is contributing to your troubles. I should also add that in marginal conditions and riding slow I think boot dragging is very effective.

 

[ewald]

For what I remember the fan ran counterclockwise, looking at the fan from behind - in forward direction.
Yes I swapped the original track to a 44mm (1.75"). The thing is that I can't drive any faster with so many people onboard. At normal speed with only me on it is never a issue. One minute after I but my boot down the lamp goes. So definitely a "drive to slow-not enough snow spray on the tunnel rad" issue. Looking for tips how to solve it.

1 change snowmobile, 2 check with others which way the fan goes, 3 replace the fan with a stronger one, 4 cut the panel more open. 5, replace the rad for a bigger one? What do you think?

 

[YukonMP]

It would really help to know just how hot it is running and if it is just peaking in the yellow zone or if it would shoot right up to red. Mooseman has a thread on here that tells how he installed a temperature gauge. It was reasonably cheap and easy.

Then you would know how big your problem is and whether you need to add a little or a lot. I could see putting a scoop over the oil tank area, opening the front at the rad, adding an outlet at the rear of the panel. Then comes a bigger rad and/or an oil cooler.

I'd like to see the problem fixed for you and a picture of the hordes you move around on the MP. I'm starting to picture the Swedish equivalent of the Thai family of five in a 90cc motorcycle.

 

[Mooseman]

Temp gauge install

I don't know what else you could do to help it cool better. I'd be careful about adding more electrical load with a bigger or second fan as this could lead to other issues.

Here's something I had seen for Nytros which might give you ideas. I think he's also working on a similar setup for Sidewinders.
Dual Fan Setup For Radiator

 

[BACK COUNTRY YAMAHA]

Has this been a problem from day one of ownership, if so might want to bleed the coolant system, possibly dealer didn't do it or didn't do it properly! If it is happening all the time regardless of snow conditions. If it was the track, your slides would be the first indication that you are not getting enough snow! This should be the first thing you should eliminate as air could stop the coolant from cycling and carrying the heat away from the engine! Cheers!