Boiling in overflow bottle

[ejmoan1]

Hey i was riding my quad for about 10 minutes and when i stopped you could hear and feel it boiling in the over flow bottle. i know the quad had coolant and the fan was running. the quad runs good beside that. im also using engine ice. it an 05 450r

[DnB_racing]

sounds like you have a issue with flow, either plugged radiator, bad coolant pump or It could be your radiator cap is allowing to much pressure . but either way I would drain system and check to make sure you get flow throw all components. make sure that your system is full first.

[MR4Engine202]

could b a bad head gasket too

[deathman53]

I was gonna say the headgasket also. When the headgasket is bad, it allows pressure(air and fuel compressed) to go into the coolant, the radiator has big bubbles of air, it eventually opens the radiator cap and the pressure comes out the radiator cap to overflow tank. It looks like the coolant is boiling, but its not.