My brother has a 01 Ruby. The other day he was driving it and after about 4 miles the temp light can on. Never had a prob before. It really doesn't seem that hot. Any ideas as to what it could be? Sounds like a simple fix, and it does run fine, no cutting out. Could it maybe be thermostat?

 

could be thermostat, check the radiator. take out that black plastic screen in front, my radiator was packed solid with mud. it even gets between the oil cooler and the radiator. stick a garden hose in there and flush it out just to be sure there are no blockages. my kept coming on as well, i ended up putting engine ice coolant makes it run like 35 degrees cooler and wont freeze. down to like 30 below. i think. could be something this simple [img]i/expressions/face-icon-small-smile.gif[/img] oh is the fan coming on, could be the fan fuse, i think there is one, never had mine go though.

 

Does he go through a lot of water and mud?[img]i/expressions/face-icon-small-wink.gif[/img]

 

The fan comes on and stays on for quite some time after its shut off(with key on). And no he doesn't do much mudding at all, its mostly up and down the road.

 

My neighbor has an 02 Foreman 450 and his fan comes on and stays on after hes done some riding(when key is on) but goes off after a while.

 

the fan is wired to the ignition somehow, so if you turn the key off it will shut the fan off. but you are probably right, it could be the thermostat. it might be stuck in the closed position and not letting coolant through. has he ever flushed the system at all? it might just need new coolant, possibly a little corrosion in there. try changing the coolant.

 

Nope, never been flushed. I'd say that would be a good place for us to start, flush it and replace the thermostat. He has about 2700 miles on it so it probably needs it.

 

In all honesty, I have never had a thermostat go bad on an ATV. Not to say it can't happen though. When I have been faced with a unit that has had the temp light illuminate, I will first check the coolant level and radiator for restricted air flow, remove the radiator cap and slip my digital thermometer in the filler neck, then start the unit and try to duplicate the problem. When it is cold outside, I will turn the idle up to about 2000 RPM on my lift and let it run like this until the fan cycles, watching for the light to come on. Sometimes this will take 5-10 minutes at this RPM. I also will track the tempurature at the top hose and bottom hose near the radiator as possible with my digital temp laser light, to confirm the cooling system is functioning properly. If you don't have any of these tools, simply remove the radiator cap and watch for the coolant to begin circulating and the fan to cycle, but be careful, if it does get hot, it will spew hot antifreeze everywhere. If the fan cycles and stops and the unit did not over heat, the problem will be a bad sender, wiring, or fan control unit. Honda has a section within the service manual that outlines a quick and efficient proceedure for tracking these problems, but you must pay attention when the light and fan come on, to cut down some of the diagnostic time, and save doing some steps of the proceedures.
Once I found there was a bad wiring, sender, fan controller unit etc.., I will confirm coolant level, set the idle back to spec, turn the unit off and reinitialize the ECM so the throttle position sensosrs calibration is stored in the ECM correctly .

----- Gimpster -----

 

Problems like this can be tricky. If your rad isn't all clogged with mud, and there's enough coolant in the reservoir and pressurized system, and the temp light and\or cooling fan seem to come on somewhat at random when your machine clearly isn't that hot, I've usually found the fan motor control unit to be the culprit. I've replaced at least one on a Rubicon, and a few on Foreman's that I can remember. You can't test the control unit directly, it's solid state. So you're somewhat forced to make an educated guess.