no heat on 318i

hey guys... my thermostate has been stuck open for the past few months, therefore, the temp gauge usually was 1/8 the way under normal driving conditions. and my heat wasn't very warm, and took some time to become warm after driving....

I have just installed a thermostat in the car, my car now operates at the normal temp range, which is half-way beteen Cold n Hot... But, my heat is not working well. It make take me driving it for 10 minutes before i can get any heat, yet the engine half way on the temp gauge 2.5 miles/ minutes into the drive.

My heat ususally does begin to work after appx 10 minutes... it works for a while and goes in and out.... i have also noticed that if i stop or come to an idle.. (low rpms) the heat temp goes down significantly, (although the car is still 1/2 between hot/cold)

do you have any ideas what specifically is causing this?


ps... my recirculate/fresh air changer is working, so its not stuck on fresh air

faulty temp gauge?

where should the gauge be at at normal operation temp? mine sits at the edge of the blue square. I'm assuming the needle should be strait up? and that means the thermostat is bad.

it could be your heater matrix. theres a common fault on them clogging up and sticking shut when you dont use bmw fluids.

I'd bet the culprit is air in the system. I had the same problem on my 94' 325i Bled the system and it works perfect now.

The symptoms you described sounds like air trapped in the cooling system. Bleed the air out and see if that works. It could also be a problem with the heater flow control valve or elsewhere, but I would bleed the air out first and go from there.

Originally Posted by 77vetteguy

where should the gauge be at at normal operation temp? mine sits at the edge of the blue square. I'm assuming the needle should be strait up? and that means the thermostat is bad.

At Normal operating temp, the guage should be right in the middle. If it stays at the blue part it could be a stuck open thermostat, but may just be a faulty temp guage or sensor.

Temp sensor in the heater control might be covered in dust. Even if it isnt the problem it is easy to clean.