Coolant Issues

[Rick Austin]

Hello,
My 2006 Z4 3l suddenly pegged the temp gauge. Pulling over, it was down about 2 quarts, coolant on the splash tray beneath the engine.
Ran fine for the next few days, no issues. Suddenly it happened again, topped off all good. Bubbles coming up the system to overflow tank so checked with a chem tester for combustion gas leak and had none, so head gasket should be intact still.
Thinking an intermittently sticking thermostat or elect water pump on the way out but too expensive to guess and through parts, any idea???
Much Appreciated
RA

 

[Mr Tidy]

Firstly welcome to the forum Rick.

To me that sounds like a dying electric water pump. I've had two of them die on me and both times they overheated within a mile.

If you do replace it make sure you get a Pierburg pump which is the OE manufacturer, but don't buy from BMW as they charge about twice as much as other places.

 

[Rick Austin]

Mr Tidy, Thank you for your response. Today I tested for gasses in the coolant there was none. I did pull a bit of what looked like oil into the tube, which was concerning, but the chem did not turn yellow. also drained. the oil and found no coolant in it or anything that looked like anything but oil. Pressure test and it did drop but could not find anything, possibly because the rad was not to the tippy top?
took for a road test after bleeding and all was good. 212 top temp.