Nearly there with the build and thought it be an idea to fit an expansion tank and was hopeing someone could assist me in fitting it.

I have drawn a diagram below to hopefully help show how i think i should do it.

My car has a ZX12-R engine with a Electric water pump , polo radiator, alloy header tank with a Stant high pressure rad cap.

I was planning on just running my overflow pressure release pipe from my header tank to the expansion tank, is this correct ?

isnt the header tank and expansion tank the same thing ?

Yeah I'm with you Warren.No point in moving the coolant from one tank to another

I just have a header tank fitted on mine. The bypass pipe from the thermostat is also fitted to the header tank, I dont think there is any need to connect it to the radiator as well. It seems to work fine and has only boiled over once and that was when a hose came off.
Dave

Well i dont think its gonna hurt fitting it and i have read on here that its a must for a track car.

I know "Athoirs" has this kinda set up wouldn't mind a chat with him if his about as he has the same engine radiator and header tank.

Has your radiator got a pressure cap? If it hasn't it shouldn't have an overflow should it, possibly just a bleed at the top.

The header tank should have a pressure cap on it so any fluid going into your expansion tank is not going to ever find its way back into the system anyway without you manually pouring it back in, and unless you're planning on boiling it up quite often, you're not going to get much (if any) water coming out past the pressure cap assuming its the right pressure rating, so the expansion tank is pointless IMHO.

If you're worried about the fluid coming out onto the road / track, just put the breather from the header tank into a catch tank rather than out to fresh air, which is effectively what the "expansion" tank is in the above diagram.

cheers

Chris

[Edited on 28/7/07 by ChrisGamlin]

Hmmm sounds like ive just wasted my time on this then.

Is it possible to incorparate an expansion tank into my system ?

My rad has no cap its the polo rad.

My cap is a pressurized "Stant" cap cant remember the pressure rating.

Ive been having problems with trying to bleed my water system, i have ran the engine with the cap off and once temp reaches about 55 all hell breaks lose and after numerous attempts it hasnt yet settled down. I just keep losing loads of water from it spitting ferociously out the header tank. Its seems to blast through from the small hose into the header tank.

Been speaking to someone who recomended to first try blocking off the small hose on the rad as that isnt needed and then maybe try fitting the bottom of the header tank to the bottom hose instead off the top hose.

Ive realised I may have been talking rubbish above, so apologies

It depends on what cap you have as to whether it can allow water it has expelled into a catch / expansion tank to be drawn back in when it cools down, but your expansion tank would need to be either placed higher than the header tank with its feed on the bottom, or have some kind of "drinking straw" (for want of a better description) arrangement so it could pick up fluid from the bottom of the expansion tank, rather than air.

Im not really sure this will resolve your issue though as it shouldnt be blowing the fluid out to start with. It does sound like an air lock or a mis-plumbed hose which is stopping the water circulating which then causes localised boiling that blows out all the water.

Try running your water pump full blast (Im guessing its a Davies Craig?) rather than using its "intelligent" control, as a mate of mine with a busa had similar issues with his and it turned out the DC pump wasnt circulating the water quick enough in auto mode during engine warmup and was causing localised boiling in the head even though the rest of the system was still quite cool. Once he bypassed this and just run the pump full chat, the problem went away.

I would also try plumbing the header tank into the bottom hose though, you're less likely to get air in the system if you're feeding water in from the bottom of the system and allowing the air to escape upwards as you fill it, rather than throwing it in the top hose where it could trap air on its way down.

[Edited on 31/7/07 by ChrisGamlin]

Yes i keep thinking that the bottom hose would be a better option and this is what people keep coming back saying.

We may have sorted the problem though yesterday my brother bought a bit of kit from work home which manually pressurizes the system and it seems to have gotten rid of the air. We then clamped up the top small hose going from the top of rad to the T piece and then ran the engine up. The water level rose when the temp reached 70 odd degrees and spilt out from the header tank but there was none of this violent jetting we had experienced.

Unsure what to do now whether to replace the cap with one that will incorparate my expansion tank ( which is actuallt situated below my header tank but the line from the header tank does go to the bottom of the tank ) OR to just run it as is with my high pressure cap but again unsure how much water i should have in my header tank or how i should gauge how much to fill it up?

Why not split the top hose and run it through the expansion tank, like a swirl pot?

I have only got 1 big inlet at the bottom of the tank and a small inlet at the top which goes to the top of the thermostat.