Hey guys! my brother just got a 95 polaris scrambler, two stroke 400. The coolant overflow jug is blowing coolant out the small vent in the cap when it get hot. It was doing this for a while througout the day but running fine, then it eventually blew off the radiator hose off the top of the head of the motor and it was really hot.
i pulled the spark plug off and it looks fine.

the counter balancer oil looks good, the antifreeze does not smell like gas??? Im confused, does it need a water impeller? head gasket ?

I guess Im just trying to figure out why the overflow is so pressurized if anyone could extend a helping hand that would be great. thanks!

 

I say it was leaking compression into the coolant. Did it blow coolant after the first wide open blast when it shouldn't have been hot yet.

 

Was the cooling fan running?

 

fan was running all day pretty much, the temp light never cam on im assuming it just doesnt work because the motor got so hot that I think it expanded the coolant fitting on the top and it actually came out, then when it cooled I cuold not get it back in I had to tap it back in with a mallet

Seems like when revving hard it would spout out of the overflow reservior and when not revving it out the coolant overflow seemed empty??? very confused, thanks for the help guys

 

Mrtwostroke, Ive got it home now and was messing with it a little. I seems now that yet, actually the overflow is empty right now, but immediately upon even cranking the motor over ( before were even fired) is it hissing pressure out of the vent hole in the overflow bottle? Does that mean head gasket is gone?

where might i find a guide to help me replace the head gasket.

also wondering what the cause of this was, maybe theres another problem and the gasket is not gone due to overheating caused by the original problem? do these have water pumps and impellers like a car?

 

I havea 95 400 scrambler, my overflow is "pissing" coolant out too upon warm up. Didnt really lose much coolat though? rode it for a while like that and it eventually popped off the coolant hose on top of the motor how do i tell if the coolant is circulating or not?

I have just heard of the bleed screw... what is its purpose, does it need to be bled periodically or just when the motor is apart or what?

does the impeller need to be replaced periodically or is it metal?

 

i believe the impellers on the 400's are aluminum and don't normally need replaced.
The temp.sensor is located at the top of the head and to make the hot light come on,just unplug the wire and touch it to ground,with the key on and the temp. light should come on .
the air bleed screw is located at the top of the head,when you are filling the radiator,you should remove this screw,and fiil the radiator until coolant starts to come out of that hole,then replace screw and finish filling the radiator.start it up and keep an eye on the coolant ,add if neccesary

 

ok how can i tell if it is circulating properly?

also why is it pressurizign the coolant to the point of it blowing out the vent hole in the overflow?

 

If you are building pressure while cranking that is a problem. New to tear it down and inspect. Could be gasket or head. Mine gets hot when not moving but my fan is not running.

 

before you start it,or right after,take the radiator cap and look inside,you should see the water moving around. If it starts belching water out soon,then you have some internal problems(bad head gasket,warped head,etc.).