Two Stroke Motocross

Two Stroke Motocross Forum => General Two Stroke Talk => Topic started by: madmangil on May 14, 2019, 04:49:45 PM

Title: cr250 losing coolant
Post by: madmangil on May 14, 2019, 04:49:45 PM
2000 cr250
coolant comes out of the overflow hose. I might lose 10-15 ounces in a half hour ride.
I tried another cap and the same thing. I bought a new cap at the autoparts store (15psi) and the same thing. I made another seal from an innertube so that there were 2 seals (the seal that keeps coolant from getting to the overflow) and the same thing. The coolant is new, the waterpump impeller looks good and turns with the kickstarter.
It doesn't idle high as if it were overheating. It will start leaking in about 5 minutes after starting cold and letting it idle in the garage. The radiator seems clean and the rim where the seal sits appears smooth and undamaged.
What could it be?
Title: Re: cr250 losing coolant
Post by: rsmith on May 14, 2019, 06:28:00 PM
First, welcome!

You probably have a leaking head gasket, that is over-pressurizing the cooling system.

--Ron.
Title: Re: cr250 losing coolant
Post by: eprovenzano on May 16, 2019, 08:25:21 AM
I agree with Ron... you're getting pressure into the system from somewhere...  I'd replace the head gasket.
Title: Re: cr250 losing coolant
Post by: madmangil on May 16, 2019, 04:13:21 PM
Thanks for the advice, I will give that a try.
If that is the case, should I see any sign of a leak on the gasket when I remove the old one?
Title: Re: cr250 losing coolant
Post by: rsmith on May 16, 2019, 05:08:52 PM
Yes, in most cases you will be able to see where the issue was.

--Ron.
Title: Re: cr250 losing coolant
Post by: madmangil on May 20, 2019, 05:21:52 PM
cylinder head gasket was replaced. The old one looked like it lost some of the rubber coating from the inside edge to one of the coolant channels. It didn't leak after a 10 minute idle. It will be at least another week before I can get a ride in. I will post the results.
Title: Re: cr250 losing coolant
Post by: eprovenzano on May 22, 2019, 09:10:51 AM
It seems as though you found the problem...  keep an eye on it and keep up informed.