couple things to check in the morn...thanks all !!! Will post back tomorrow on the scoop!

 

Freezing cold out today, so did not start fire in garage, so no updated - will try this week again...thanks again guys!
Randy

 

A couple of things about the thermostat and the radiator sensor. The thermostat should open at 150, give or take a couple of degrees. Easiest way to check is to put it in a pot of water, stick a thermometer in the water and turn on the heat. You will know if it opens when you see a few bubbles in the water. The sensor is suppose to turn the fan on at 197, plus or minus five degrees. Stick a thermometer in the radiator and let the temp rise and wait to see when and if it kicks on around that temperature. This is all referenced in the OEM service manual. NOTE! when you reinstall the thermostat, pay close attention to the vent hole alignment. There is a little indicator on the head and the vent hole is to be in line with it. That is to make sure you have proper coolant flow.

 

-35 C and -48 with windchill here today, so I have not played with the bike anymore......sitting low inside the house!
Will update as I proceed. Going to take bike to buddy's to test the other relay by the handlebars with ohm meter first thing.
Cheers

 

Update finally....OK, took the quad out finally, snow was all gone. Took an infrared heat sensor..obvious with it that thermostat worked as we could see the temps differ at different areas (pre water pump, post water pump, rad, etc.) Never got it over 165 on a 13 mile run over fields and some minor mud..but cool day.
This weekend, pulled trailer to and from our cabin in woods....only a 5 mile run, but pure mud all the way and worked the bike...My honda foreman fan is on a bunch, brothers 660 grizz, fan was on, other brother has a 450 kodiak, fan was on, and has the identical 400 as mine and fan kicked in....guess what, mine did not...took the heat gun to the hose, 184, at the radiator 200, but heat light nor the fan kicked in....
I just read that maybe it needs more than 200 to kick in though ( but my recollection was the rad sensor was supposed to be lower than that)....what/when should it kick in, if 200 is too high (never checked head temp...darn) at the rad, what else can I check, or should I just hotwire fan to be on with ignition always....
Thanks and sorry this took so long to test.
Randy

 

Ended up just cutting the wires off the new sensor I bought...crimped them together...liquid black taped them and the fan runs when the key is turned on...
Seemed like the least hassle way to go.....
Guess an fan motor is cheaper than a motor!

 

Hmmm. I see Celltech says 197 for sensor to open...so it could have needed more than 200 ( I checked temp right at sensor) and it was 200....maybe I should have waited for 202 and let it idle a bit...200 just seemed hot especially when the Grizz and the two other Kodiaks and my HOnda all had fan on with the same run..hmmmmmm now I am thinking...maybe always on fan is not needed and not way to go...any thoughts>?

 

Read all posts, the first thing you said was rad was dry. I would suspect leak in radiator, radiator cap, (weak spring), or water pump weep hole leaking. Bottom of radiator may be filled with crud, covering up fan sensor pickup.

 

actually, the hose was cut by a tree or something, so that leaked out the fluid....cap and such are good..but I like you thinking of the sludge...although when I removed old sensor and put in new I remember looking in the rad hole....clear, but did not swipe my finger in it to see if there was any sludge on the bottom....

 

I have an 01 Kodiak that had exactly the same problem. Sensor changed, no change. End result was the water pump shaft had broken. It is really easy to change out, the parts were about $35 ( get a new gasket too). Go to yamaha.com and you can look at parts diagrams online free and get the part number. The pump slides out of the left side of the engine, under the cover that is just below the pull cord. About 4 bolts and it slides straight out. The shaft and rotor are one part, but came out in two on mine. Only takes a few minutes to check, just have some high temp gasket sealer handy.

Good luck, please do let us know what you find!

Jim P