coolant question

[jpinhb]

If there is an airpocket in the system will it boil out the coolant ?
I went riding this past weekend and after riding a few minutes I stopped and I could hear the coolant boiling , I took it back to the truck and added some coolant and rode a few more minutes and it did the same thing . But I was never able to get all of the air out of the system .
I just looked at it tonight and it's low again . There are no hint's of water in the crank case either .

[KXcam22]

I'm not 100% sure, but I think you are correct.  It is the pressure in the system that raises the boiling point. The higher the pressure the higher the boiling point. If there is air in the system the pressure can't increase as much due to the air compressing. Shouldn't be too hard to get all the air out. I tip my bike over when I fill and run it with the cap off for awhile. Also don't forget that little bleed screw on the cylinder head. Hope this helps. Cam.

[jpinhb]

Thanks  cam ,
I'll look at it again tomorrow . I hope the problem is just that it wasn't full to begin with and the air pocket boiled the water . I'll keep ya posted .

[alan]

You need to make a pressure check! Yhe cap could be bad, I would check it first or just replace! NO or Low Pressure It will Boil!

[doordie]

Just a tips after you have fixed your cap and a pressuretest,you can use "Engine Ice" it?s a good coolant which is lowering engine temp 5-10 degrees and makes a litle bit of power too.

//doordie

[2001KX5]

If your head gasket is going then it could be blowing into your coolant. Check your coolant with the bike running for bubbles, and check it for an oily sheen when not. Also make sure there are no pin hole leaks in your rads that could be letting very small amounts of fluid out that yuo woudlen't really see behind all the muddy mess that usually gets on them.  I had that problem on my last KX250.

I used "Water Wetter" in my turbo charged honda civic and its amazing stuff. It will def be going into the kx when I'm ready to refill the system. It also acts as a lubricant and prevent corrosion.

[FuriouSly]

   Boiling radiator fluid means too high a temp.  This is generally caused by running too lean, lugging the engine, riding with the wind, dirty air filter, and water pump impellar damage or failure.  If your bike was fine before the problem, look to the impellar/air filter.  If it is after a rebuild or new part addition, look to the jetting.
   More than likely the fluid loss is from the over temp and dumping fluid out the overflow when riding and you not noticing it. The lower level of fluid is from boiling it out, not neccesarily a leak in the cylinder or rad cap failure.
   As noted before, pin holes in the rads will lower the fluid levels without being very obvious, especially if they have built up dirt on them.  If you don't "keep it clean", it's hard to catch the little stuff before it gets big.  Also look to the radiator tabs that mount to the frame or shrouds.  The heavy vibration of the KX5 and laying down the bike will cause some stress on these areas.  A leak may start there as well.

Sly