Hey there, have not been on a while, actually forgot my old username....could use some help:
2002 Yamaha Kodiak 400 4x4
-heat light came on 15 miles back in bush on moose hunt
-limped bike out hitting water here and there and unhooked trailer
-got it home, hot wired fan - works (never kicked in though)
-pulled wire off bottom left of rad (thermo switch assembly) - ran wire across and fan kicked in.
-bought the assy - 80 bucks Canadian!
-replaced, filled rad back up, fixed hose....took bike out...
Now it is very cold here, but I ran the bike through the snow in 2 wheel drive to make it work....gave it a good run. brought it back in heated garage to idle, checked - fan is not on....but heat light is not either....
-felt the motor, hot, spit on it SIZZLE
-rad hoses are hot.
-shut bike off, turned switch on and fan not kicking in.....
-I don't trust the red dummy light, but it did come on when I was heated in the bush....
-Anyways...guess what I am asking in, is how do I know how hot bike is and when fan should kick in.....how do I know if dummy light is working now... (rad was empty when I tested the thermo switch assy..hope it was gone and did not waste money...
-Thought I had this one solved - assy, fix hose (which I did not know was cut in bush when bike heated, found out when I removed thermo assy and there was no rad fluid in rad, yet rad resovoir was full - quite decieving...
-Any ideas and help would be most appreciated!
Randy

 

Couple of other things to check, Randy. Is your the water pump circulating coolant? How about a new thermostat?

 

HC, thanks for the prompt response...I was just searching for both those items...was wondering about them....questions:
1) how do I know if water pump is working???? What do they cost (yikes!)
2) what does the thermostat do and how can I tell if it is working - would it make the fan not kick in?
Thank!

 

Randy, the thermostat is rated a certain temperature such as 180, 200, etc. It keeps the water in the engine at that temperature. When temperature exceeds that rated temp then the thermostat opens to circulate the coolant through the radiator. I don't know about ATVs but in cars, you can remove the radiator cap when the engine temp is below the operating range and watch the coolant in the radiator. It won't be moving until the thermostat opens when the coolant reaches operating temp, then you can see the coolant moving through the radiator. That way you know that the thermostat does work as well as the water pump. That would tell you that both the pump and thermostat work, BUT not necessarily as well as designed.

Not sure why the fan is not kicking in unless the radiator has not reached the initiation temp and that could be because the thermostat is not opening.

You can check prices at Rocky Mountain ATV and here's a link to a service manual for the Kodiak:

RM ATV

Srv Manual

 

there should be 2 hoses going from the radiator to the engine. if your thermostat is working, when the engine is warmed you should be able to put your hand on both hoses and they will be pretty warm. if there is an overflow tank you can squeeze the warm hoses and the level of fluid in the tank willgo up and down.

this will only happen if the water pump and thermostat are working.
O, and if you just refilled the radiator make sure to warm up the engine and "burp" the radiator. you do that by takeing the cap off the the overflow, and or radiator, and squeezing the hoses. the fluid level should go down if there is any air in the system. BE CAREFUL TAKEING THE CAP OFF THE RADIATOR!

 

Thanks those are some great tips...still funny the fan would not be kicking in....and not sure how I would drive bike to heat it up a bit then take rad cap off to see if it is circulating....or would idling bring heat up that much???
I am thinking regardless of thermostat and water pump, that darn fan should still kick in.....Water pump is not leaking either.
I am going to look into the thermostat and go through that manual to see if there is an inline fuse somewhere I do not know about.
My bike is an 02 - one time on an atv forum I had found a srvc manual for it..this one is for 05 06 it looks like but I would think it would still have some ideas...
thanks again HC!
Randy

 

Cherokee...great idea on the two hoses and temp...I will check that out tomorrow and see what the scoop is there...does that pump generate a lot of pressure...as in how firm should the hoses be?

 

I can idle my Grizz 450 and the fan will kick in after a little while, but my temps are a lot warmer than yours are now. According the diagram in the manual, Pg 53, the fan sensor is on the radiator. If the thermostat doesn't open, the coolant in the radiator is still cool and the sensor will not initiate the fan. That is one possibility.

 

Hey, look at pg. 358 circuit breaker fan - do you think the fan motor would run if that was gone and I pulled the harness off on step 6 and hotwired it and fan worked????

 

Could be the problem. Also, you might want to warm it up and stick a thermometer in the radiator coolant to check the thermostat.