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Discussion Starter #1 (Edited)
I'm not sure if it was this forum or not but I saw a thread with someone having the exact same problem as me but he never posted if he found the problem.
Whenever I turn off the bike the coolant starts boiling over and dumps half of the radiator out the overflow tube.
The bike is an 05 zx6r
 

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Sounds like the boiling temp in the coolant is too low which means its not a proper mix of water and coolant or there's insufficient coolant in there/too much air. With it pushing coolant when the bike is off (I don't think ZX6's fan runs when the bike is off, mine doesn't), It means with the increase of temperature from the bike turning off (my bike will usually jump at least 10 degrees when I turn it off) it is hitting its boiling point and causing the radiator to CORRECTLY deal with the problem by shooting the expanding steam and coolant out of the radiator overflow

I would simply just do a full coolant change. When doing the coolant change and filling the coolant back up, squeeze the coolant hoses to push out trapped air and purge the air from the system using the method described below.

Run the bike for a few seconds so the coolant moves around, take the radiator cap off and run the bike again until the coolant reaches the top of the radiator cap, while squeezing the coolant hoses to push air out of them. When coolant reaches the top, seal the radiator. This will push all the air out of the system. Then add coolant to your coolant overflow reservoir between the proper measurement lines.

ALSO, I would double check your radiator cap and hoses. If you have signs of any fluid residue around these points, just replace the radiator cap or reseat and reclamp your hoses (replace if damaged/cracked/ripped). Sometimes this problem starts with a faulty radiator cap or a hose leak that slowly pushes fluid out of the system and lets air into the system. When Air gets into the system, these air pockets can prevent the coolant from moving around the coolant system. This is usually indicated by the bike running hot or overheating and the fluid in the coolant reservoir overflow expands instead of entering the coolant system.
 

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Soooo many things to list with such little info provided...

Potential Issues:
1) Coolant system needs a flush (Cheap and easy to do)
2) Bad radiator cap (Cheap and easy to do)
3) Bad Sensor (Not so cheap....test it)
4) Bad Thermostat (PITA to change IMO...but cheap part)
5) Tubing/piping - Maybe clogged/rotted lines?

Anyways...try some stuff mentioned in above posts and good luck :)

Oh...and please let us know what works so we don't get another post like this stating no solution was posted ;)
 

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Discussion Starter #8
im gonna try to respond to everyones suggestions in one shot...
Radiator is new hoses are new cap is new
thermostat is working properly
pump is also working properly
i Cant tell you what the temps wer cuz i didnt have a gauge cluster on all last season but i just got one a few days ago
It could be the boiling point thats the issue cuz i was running straight distilled water (I didnt want to keep buying coolant until the problem was fixed)
and it could possibly be air in the system but i filled and did everything neccessary to get the air out about 30 times last season.
Im gonna go get some coolant and throw on the gauge cluster before i bother you guys with this bullshit issue anymore
 

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Distilled water boils at 210 Degrees. So if its not happening most of the time when the bikes running, that means your bike isn't reaching the 210 point. Which would indicate to me that if its mostly when the bike turns off, your coolant system is acting like it should. My bike runs on average around 200 degrees on a normal temperature day, so with the expected 10 degree bump from the bike that stop moving and fan that turns off, that would easily push it over its boiling point. Water starts to become steam around 250 degrees and your not pushing steam so its definitely not that high where heat at that temp could crack the block.

Sounds like you just need a coolant change. Coolant raises the boiling point and should stop your problem. If it starts to happen again, then there's a leak, somewhere air is getting in, or something else is fault.
 

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Also make sure your lines to the overflow tank aren't backward. When I bought my first bike it would dump fluid out of the over flow every time I rode. I finally found out that the idiot who owned it before me had hooked the overflow lines to the resevoir backwards.
 

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I had the exact same issue. I flushed the whole system with a mixture of white vinegar and distilled water a few times and flushed it with just distilled water to remove the calcium build up in the system. After all that, I decided to change out the thermostat and radiator cap since they were cheap. Once all done my bike did not go past 190 unless at a light. It's been almost 2 years since I changed the coolant and will running nice and cool.
 

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I had the exact same issue. I flushed the whole system with a mixture of white vinegar and distilled water a few times and flushed it with just distilled water to remove the calcium build up in the system. After all that, I decided to change out the thermostat and radiator cap since they were cheap. Once all done my bike did not go past 190 unless at a light. It's been almost 2 years since I changed the coolant and will running nice and cool.
There you go :bigthumb:

bjaroch...take a leaf out of bsemilla's book there. Do a basic flush and perhaps change thermostat and cap. Unless your sensor is bad I can't imagine why it should overheat. :O
 

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Distilled water boils at 210 Degrees. So if its not happening most of the time when the bikes running, that means your bike isn't reaching the 210 point. Which would indicate to me that if its mostly when the bike turns off, your coolant system is acting like it should. My bike runs on average around 200 degrees on a normal temperature day, so with the expected 10 degree bump from the bike that stop moving and fan that turns off, that would easily push it over its boiling point. Water starts to become steam around 250 degrees and your not pushing steam so its definitely not that high where heat at that temp could crack the block.

Sounds like you just need a coolant change. Coolant raises the boiling point and should stop your problem. If it starts to happen again, then there's a leak, somewhere air is getting in, or something else is fault.
Just an FYI R&B, the boiling point of water is a function of temperature and pressure. If the system is sealed and there is no air in it, then there is no room for expansion and the pressure in the system rises rapidly without the water boiling.

Check out the table in this link:
Pressure and Boiling Points of Water

Of course, there is a point where the temperature will rise faster than the pressure it induces especially when hoses are expanding and effectively retarding the pressure rise, then boiling occurs but this can be well above 210 (your 250 point maybe). If there is air in the system, expansion is allowed to happen and the pressure doesn't rise fast enough to prevent boiling, so it will boil at a much lower temperature.

Adding salts or organics (like glycol) will raise the boiling point further but the system really needs be sealed tight and air free to allow the pressure to build and prevent localized boiling at the hottest point like in the block or head.
 

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Just an FYI R&B, the boiling point of water is a function of temperature and pressure. If the system is sealed and there is no air in it, then there is no room for expansion and the pressure in the system rises rapidly without the water boiling.

Check out the table in this link:
Pressure and Boiling Points of Water

Of course, there is a point where the temperature will rise faster than the pressure it induces especially when hoses are expanding and effectively retarding the pressure rise, then boiling occurs but this can be well above 210 (your 250 point maybe). If there is air in the system, expansion is allowed to happen and the pressure doesn't rise fast enough to prevent boiling, so it will boil at a much lower temperature.

Adding salts or organics (like glycol) will raise the boiling point further but the system really needs be sealed tight and air free to allow the pressure to build and prevent localized boiling at the hottest point like in the block or head.
Thanks for the informative post!!!! Forgot water acts different under pressure! Thanks!

 

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Discussion Starter #17
Between a fresh mixture of coolant and getting my radiator off the exhaust manifold the problem has been fixed. Thanks everyone for the help
 
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