Radiator Cap?

[RonRock]

So my wife's 07 Z4 dumped coolant overnight after the days drive. Significant amount. But a quick look and I can not see any obvious leaks.

I have a Stant pressure tester for cooling systems. As well as a pressure tank that I use for brake systems. Is there a pressure cap that will work on the BMW Z4 that I can use to pressurize the system?

[cbpip]

Best radiator cap for the Z4.
https://germanautosolutions.com/gas-...coolant-cap-2/

[RonRock]

Thank you, but I was looking for a cap that I can use to pressurize the system to help find a leak.

But I must admit that I went into panic mode with this one. Turns out it was simply the windshield washer pump. The pump was leaking out the seep hole, Washer solution was blue, looked same as BMW radiator coolant. Closer inspection proved the issue. What through me off initially was that the radiator was a bit low on first check. I did not top it off until after I found the washer pump was the actual problem. Radiator took a very small amount. The indicator is quite sensitive.

So new pump is ordered, washer tank emptied. Will use a different color washer solvent in future.

The tank is near the area I would expect ti find a thermostat leak. Maybe my report will help someone in the future.


Still would like to find the cap so that I can get one on hand.

[Our03z4]

My guess is the coolant tower, they get pin hole leaks that you won't see until up to temp. I'm 2 for 2 on my Z4s doing this.

[Our03z4]

Sorry didn't read your next reply. If you haven't done the tower yet do it. It WILL go bad.

[cbpip]

Harbor freight sells the kit with it in it.

[RonRock]

Originally Posted by cbpip

Harbor freight sells the kit with it in it.

For the BMW? I didn't even think to check HF. I will.

Thanks