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2007 Kawasaki kx250f coolant leak from overflow tube

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I've got a 2007 kx250f that keeps leaking coolant from the overflow tube. I've replaced the radiator cap thinking it was just that because the old one was so weak, but it didn't solve my problem. I put the coolant just above the fins inside the radiator to allow for expansion like it recommends but it still leaks quite a bit, I didn't know if you had to purge the system somehow to get all the air out or if this could somehow be a head gasket problem. Thanks

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Are you talking about the tube that in the neck under the filler cap? Pressure raises that. Heat causes that. A new cap nor a higher pressure cap doesn't change the fact the motors hot. 

If there isnt silicone in the motor plugging up a hole AF goes through, then you have to cool down.

Is your impeller bolted fine and rotating?

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By nature the system bleeds out air automatically when the engine is running. When is it leaking? Is it excessive idling or not riding fast enough to get air moving through the radiators? If its not user error then check the water pump for issues as stated above.

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Thanks for the responses, I'll look into it as soon as I can, I just rode all day with no noticeable heat issues, but it seams to leak when it just gets warmed up then periodically after that, it's only like 2 or 3 tablespoons everytime, but after awhile, like 3 or 4 hours of riding it gets pretty significant.

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As GasMixer44 mentioned, letting the bike idle too long is bound to make this happen. Similarly, if you putt around the trails or track too slowly, you'll see this start to spill out (this has happened to me a couple of times). Getting on the gas to get the air moving should really help. In general, if it's only leaking while it's on I would most likely suspect something is making your engine run too hot and you're just not getting enough air to cool it off.

Fwiw, I notice on my 2t that I can let the thing idle and have almost no heating issues; I never had coolant overflow on it. On my 4t though, I never let it sit more than a minute before getting a move on. If on the trail and we stop, the bike gets shut off until we're ready to move again.

Also, even with a little bit of overflow, I wouldn't expect it to cause a problem. If you have to add coolant every 3-4 riding hours, then something is most definitely up.

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I was riding slower trails all day and around the house is usually slow, I'll check to make sure the radiators sent all gummed up then go from there. Thanks

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I have much experience with your problem... I found adding water wetter to the coolant helped a little adding a 1.6 bar cap helped a lot, and keeping the move on helped a lot. 

 

TO check the head gasket, pull radiator cap, start bike, and look for bubbles in coolant. I doubt this is your problem because a blown HG typically creates a chronic overheating problem, ESPECIALLY IN THESE BIKES.

Also, for the record, running less EG, and more water in the coolant mix, I prefer 70% water/30% EG, creates a more efficient system. This is where the water wetter really comes in handy. It really makes the water work better at removing heat from the engine and putting it into the radiators. In the place where I live, Las Vegas, I could probably run 100% water and see great results, but I do go to places where it gets cold at night.

Anyway, these are my experiences and what I know. Hopefully they help!

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I ran 100% water in Arizona. I now run Water Wetter and water in Southern California.

I also have a DC powered 5" radiator fan on a switch for when Im going too slow to move air through the rads.

I have aftermarket rads too which are like twice as thick.

I also have a TTO gauge.

Edited by notoriousE-R-I-C

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Anytime I bring up the whole water thing, usually the backlash is huge and people just go off. It works though. And I don't see the advantage of using 50 50 coolant unless you live in Alaska and ride in the winter. Water simply cools better, when water wetter is used...

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Thanks for the answers, it's difficult for me to run pure water, as I live in the northern part of Indiana and the bike stays in the garage all winter, but I am running engine ice. 

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