Coolant leak - high pressure in hot weather

[sjosephs]

Hi all.

I had a new radiator fitted to the 1997 Z3 about a month ago. The missus drove the car on Tuesday (extremely hot) and spotted coolant leaking when she parked up on returning home. It was collecting in the pan in front of the radiator and draining through the drilled holes at the bottom.

I topped up the filler with water and let the engine run and after a few minutes the water started leaking again. Saw some liquid around the filler cap.

Tried again today, topping up the filler unit and letting the engine run. The level increased by over an inch in the 30 minutes or so and the temperature gauge got to about 75% (2 o'clock position - getting close to red) before I switched off.

Any immediate ideas?

 

[Duncodin]

I don't know if the filler cap has pressure relief valve built in? I'd be checking that. The seal in the filler cap etc. I don't think it should be relieving itself at the temp you describe.

I'd make sure the system really is full and not got an air lock?

When it starts leaking is the hose into the radiator really hot? If it is not then thermostat needs looking at.

 

[Andyboy]

I daresay the fan isn't working.