Overheating issues

[crash n burn]

I have a 2005 450r and this past weekend i noticed when i went trail riding after riding for a while on the longer faster sections when i stopped to wait for the other riders to catch up after i shut my quad off i could hear coolant bubbling which it never used to do. I rode for another 2 hrs. took about a 2hr break then about 15 min into another ride the coolant boiled over but the overheating light never came on. It wasnt dusty or muddy my radiator wasnt dirty it was warm outside about 90, what could my problem be.

[pro-rider46]

do you run a fan or ride through slow tight trails?

[crash n burn]

the fan was running and these trails were fast i was wfo more than just leasure riding

thermostat?

[crash n burn]

thats what im thinking but im not sure. I dont have a service manual so im not exactly sure where to start.

I would take the thermostat out and see what happens.

[450R_lover]

My started doing the same thing. I tested the thermostat and it was working fine. I then cheacked to see if the water impellar was turning smoothly and it wasnt. I took the side case off and checked the bearing for the water pump and it's bad. I'm replacing the bearing, seal, and mechanical seal to see if that fixes the problem.

[JessetheKid]

how did you check your waterpump???

[450R_lover]

well.. i just took the cover off the water pump.. then turned the impellar and it seemed like it was turning rough. Like it wanted to catch and stuff... so i took the sidecase off and checked the bearing that is in there and it was bad. You just put your finger on the inside of the bearing and see if it rolls really smoothly or if it seems like it has grit in it.

[hendershot106]

my 450r was warm enough last year during indoors when it was a little low on coolant to warp the thermostat shut---- check your thermostat- its def worth the time-------- thermostat cheaper than rebuild completely.