I have tried a few things to cure this, my set up is a TD04 and a civic rad.
Before I go any further, I had a problem before with the stock rad and ct9, running 1 bar. It pushed out water once or twice in the summer, after a good ragging. Using a rad flush sorted it out.
I replaced my stock civic rad with an "e bay" 55mm one. It ballooned under the pressure in the system after a lengthy test run. I removed it, flushed the system, fitted a speedvision gasket, used new bolts and checked block and previously skimmed head for warping, and replaced the new water pump I fitted (a 4EFE 6 blade impellor) with the old stock water pump and the problem was solved.
Until yesterday when I noticed the temp rising after a hard long run. I have found that the fan comes on about 93 degrees by my guage. But it goes OFF at about 98 degrees, the coolant can then reach 105 degrees. I dont know why the fan does this, but its not a cause of overflow bottle problems as running it all the time just delays it.
I have come to this conclusion.
Increasing the system pressure by the cap only increase the boiling point of the coolant, but once it leaves the cap, it is under less pressure, hence coolant leaving the cap at 105 degrees, is not boiling in the system as it is under pressure, but it boils as soon as it leaves the pressurised system (in the pipe and overfow bottle). This boiling water then heats and aerates the coolant in the bottle, causing it to expand and bubble out.
I think the standard cooling system does struggle to keep higher power engines cool, I am not sure if the smaller rad is the problem. I think the civic rad is more efficient so I dont think it is the cause.
I dont think its the water cooled turbos as I have ran without the water lines on and it made no difference.
I have thought that getting a larger capacity of water through the head might help, Dub 7 has started this in his rebuild, but the diameter of the holes in the head gasket kind of determine how much coolant flows. I am thinking the less time it spends in there the less it gets heated.
A faster turning water pump could also help, this can be achieved with a smaller pulley on the water pump, I have looked for one but had no luck. Maybe one could be made.
Remember the best coolant is pure water. Antifreeze makes water boil quicker, due to reducing its coheision, water wetter returns it to the same properties as pure water only.
It is possible my head gasket has gone again after 3 months, I am running nearly 1.4 bar, I am waiting a while before looking back at that.
Thats enough shite from me, I hope you have not all lost the will to live!!
) there is less and less in the car, which eventually boils over and you overheat. If the car isn't overheating but is still spitting water out, that's the only cause I can think of other than a knackered HG. 