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Tejijohal 12-27-2012 12:14 AM

Heater blow cold air and car overheat
Hi all. My z3 1.9 1999 heater blow cold air and also engine overheat when drive slow or in traffic. There is no coolent leak and i bled the system already.

Droptop85 12-27-2012 02:02 AM

Either you have no coolant or your thermostat is stuck shut

Tejijohal 12-27-2012 02:58 AM

Thanks for reply. Coolent is full I have checked few times. If there is thermostat problem how do i fix that ? I am wondering if the water pump is working or not

Droptop85 12-27-2012 03:07 AM

It's hard to say. I would replace te thermastate and thermastate housing before replacing the water pump. Reason being it's cheaper. While the vehicle is running and at operating temp try squeezing your radiator hoses. If they they are super stiff you have built up psi. They should be squeezable while the vehicle is running and at normal operating temp. If not. Thermastate is stuck closed.

Tejijohal 12-27-2012 09:14 AM

Thanks for help. I will try that

morrieschoice 12-29-2012 06:10 PM

2 Attachment(s)
If you decide to replace the thermostat, strongly consider replacing the water pump. Make sure you get one with a metal impeller....(see photo of 'new" pump with composite impeller). This is what caused my car to overheat after replacing the entire cooling system.

dougmcintyre 12-30-2012 09:00 AM

Does the car have the original cooling system? If yes or unknown, I'd replace every component of that 12+ year old cooling system. The component quality of our cooling systems are, ahh, sketchy.


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