hey ive got a s4 turbo and ive replaced the stock fan with a elec one. ive done a coolnat flush and have managed to fix my coolant leaks. at the recent track day and sometimes on the street when i thrash it it gets really hot like jus bout 3/4 up the temp guage once ive been reving a bit. i only pull bout 7000rpm max, it neva overheats at traffic lights or nething or when its just idling away for ages so im kinda confused?? do i need to underdrive my waterpump?? or could the belt be slippin?? cant hear ne schreeching.

ps my elec fan isnt shrouded yet but i thought that would only affect it at low speed

 

You don't need to underdrive your Water Pump via Pullies. That would make the car run much hotter and, In your case, negate It worse.

I think you answered your own question with the unshrouded efan. I'd check Into getting one.

 

yeah but i thought the shroud would only affect it at low speed. it doesnt overheat at idle or stitting at lights in rush traffic etc. i thought at speed the efan doesnt make much difference as its just airflow that cools the radiator

 

Try throwing on a different fan. Could just be a shitty one you have. Are the fins clear of dirt and debris on the rad?

 

do you still have the front under cover panel on? The plastic panel that runs from the bottom front of the bumper to the back of the front lower cross memeber?

need that on to force the air through the rad and oil cooler.

 

Are you using Redline's Water Wetter in your coolant mix? That will help.

 

check the grounds. my car overheats now same sort of situation. and I was told that it may be bad grounds, my car runs cool at idle and up to about 3000 rpm after that, it will slowly climb the longer I stay above 3000.

 

Make sur the Water pump housing is not pitted and corroded away on the impeller area, "machined portion"

Also:
Mazda OEM thermostat and Rad Cap
Was oiler Cooler flushed during rebuild. (30% of Cooling Capacity)
Are Oil Cooler Fins clean and not bent over, clogged with road debris.
Is the Lower hose in good condition? Does it have a spring installed to prevent collapse at high RPM's?

More to come when you answer the quickies?