Hi, I have a 2004 Polaris Trail Boss 330 that is working very hot. It has that special smell and after 20 minutes of riding I experiment a power decrease. I do not know where to start to find the problem, could some one help me to find the origen of the porblem?[img]i/expressions/face-icon-small-mad.gif[/img]

 

Are you sure it's running hot? Is it just the smell that makes you think its running hot? I guess I would start by making sure your engine is not low on oil (and that it is clean). Also, make sure the oil cooler has no mud / debris packed inside it and that the fins are in good shape.

 

I´ve been working on it, and I found that when I take the jumper (offset) the fan starts working and the red light of the temperature turnes on. The fan does not turn on after several minutes of use, and then I feel the engine very hot. Also, when I was testing the thermistor, putting it in hot watter did not turn on the fan in a reasonable time, and when it did it, then it was not possible to turn it off, even if the thermistor was in cold water. Something is rare. Do you know what is the reason of the jumper (offset)? Do you know if the fan and the temperature red light have to turn on always at the same tiem or should be separatelly? Do you know what is the temperature that the oil should be in order to turn the fan on? I am driving myself crazy because there is no sence of what is happening, so if someone is specialized on Polaris oil cooling systems or have had an experience like this, please let me know.

 

Unfortunatley, I don't know how that particular fan / cooling system works. I know how my old 425 works (and I think I know how my 700 works). My 425 had a temperature switch on top of the radiator (it's sole job was to turn the fan on and off) and a temperature sensor on the head (this sensor would trigger the over temp light on the dash).

If I understand what you are saying, it sounds to me as if your temp sensor (thermistor?) is not working right. It should turn on at a given temp and shut off at a given temp.

What do tou mean by jumper? Is this where the wires go into the fuse block?

 

Is hard for me to explain since english is not my first language besides the fact that mechanics is not my expertise, but unfortunattely my ATV spent already two months at different shops and seems like no one knows the root of the problem. If you are able to access in internet to the parts manual of this model (2004 Trail Boss 330) you will see the in the page A9 parts 11 and 12 the ones named as thermistor and thermister. To me one is the temperature bulbe and the other is like a resistor. Something crazy is going on, since the oil level is fine and is new, the oil cooler is clean. In the test I did today, after the temperature bulb was in boiled water for 25 minutes the fan started running but, again after 15 minutes the fan did not turned off!!!! even with cold water, so, could it be somethig related to the "main brain" of the ATV? I appreciate your help.

 

I am afraid I don't any more about your problem. Maybe somebody else on this page will be able to help you out. I will see what I can dig up in the mean time.

 

Well, first question is... Did either of these shops change the thermistor?
Sensors can go bad, even if they aren't very old.

Most temperature controlled circuits work in the same manner.
Either power is run to one side of the thermistor and when it reaches a certain temperature, the switch closes the circuit and lets power through to the other side which would turn the fan on.

The other way is that power is run to one side and the output signals a relay to send power to the fan.
Since a trailboss does not have a computer, it cannot be computer controlled. And I am sure they would (at least I hope) have designed the cooling system to be as simple as possible.

My girlfriend has an 04 trailboss 330 also. The fan very very rarely comes on while riding, usually only when we have been riding hard and come to a stop for more than 15 seconds in which it will heat up more.

So I would see if replacing the thermistor fixes your problem.


-Chris

 

The fan is only for the oil cooler. The motor itself is air-cooled. PM me the shops you've been to. If you haven't been to the one I go to I'll give you their info. They all race there, so they know what to look for, also they have a great mechanic.