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ive got a coolant leak. the coolant is coming out of the overflow bottle, which is about half full. but the rad is empty.. whats going on?

Does this happen when the bike is running/hot? Usually a sign that its over heating when coolant pisses out of the expansion tank.

are the pipes the right way round on the coolant tank some clown put them the wrong way round on mine

ok i think i may have sorted it, air lock in the rad, update tomorrow,,

nope not soted... im trying to test teh thermostat, but it doesnt open until the water starts to boil... is taht ok? can i run the biek with no thermo?

you can run the bike with no thermostat it will just take longer to get warm which wont be soo bad in this heat, drop the thermostat in boiling water to test it.

ye i put it in boiling water, but the thermo should open at 80, but it only opens when the water is really boiling... is taht ok?

tbh for the price of a new thermostat i would put one in anyway while you have got the bike apart.

too late lol, anyway i will se if it continues to leak, if not il get a new thermo.. cheers,

right this is wahts happening... all the coolant is being blown into the overflow bottle from the rad, and then out of the overeflow. what could be causing this?

ok, is the bike overheating? have you checked under the rad cap to see if there any tiny bubbles present? take the cap off and run the engine to let any air gaps through, you can let it get pretty hot with the cap off to allow the thermostat to open and the coolant to flow round the system, when it gets warm squeeze the coolant pipes to help any air through the system, bear in mind they are gonna get hot so don't scald yaself!! you know the thermostat is working so there's no problem with that and the water is running around the system, is the coolant mixture ok? in this weather if you only have water in your system the bike will get hot quicker and boil, you need antifreeze to keep the bike cool in the summer as well as stop it freezing in the winter.keep the bike running, the coolant wil rise as it gets hotter, keep an eye on your temp gauge and also make sure the fan kicks in when it should, if the temp gauge is getting too high or the water is boiling and overflowing then stop the engine, if it gets to this point all air should have escaped, let the bike cool and refill as neccessary.run the bike as normal,If the expansion tank is still overflowing i would suggest taking the rad off and flushing it through with a hosepipe to make sure the coolant is flowing through and there are no blockages in the rad. If your tank is overflowing then there is a blockage somewhere, normally the thermostat sticks, this can be to poor coolant mixture and it rusts up and seizes, otherwise you can get blockages in the rad? failing that i would start looking at the head gasket.

right.. ive checked most things...it all flows freely, and when i top the rad up it dont leak, it will also ride fine for half a day or so.. then it will start pissing out, then start to overheat, also the fan dont work when the fluid comes out, obv cos it cant sense the temp....im feeling head gasket... is this hard?

if the fan is not working when it is overflowing i would check again for air gaps, it can take several attempts to remove airblocks in the system.how many miles has the bike done?

bikes done 18,000 miles. and had no engine work donw, not even sure about services....
i dont think its an airlock, ive tried many times to remove air.
the fan only comes on when u tilt the bike over to teh left, but i know why taht is happening.. because the rad has no fluid in it.

someone said to me taht the head gasket has gone and it is pressureizing the system... boiling it and causing it to overflow... sounds about right.

what i think i may do is put the bike in a shop, get the head gasket done, valve, cam chain etc etc.. but im not sure how much this will cost.. anybody got an idea?

i was going to say check your water pump is working and not seized, quite how you check it i'm not sure? but the head gaskets are prone to go on the zxr400 around 16-20,000 miles so good chance it has gone.