'01 530i Overheating PLEASE HELP!

[slate530i]

Hi, my 2001 530i seems to overheat once every 3-4 months, I open the hood and there is no coolant. I filled it with water and its been ok. My mechanic tells me that he doesn't see a leak. What else could be eating my coolant?

[Trevize]

bad filler cap.

The spring gets weak and lets it leak when hot/under pressure.

[cnn]

Cooling system consists of many many parts that work together.

If you have more then 80-90K, consider doing the whole cooling system. On the long run, it costs less. Here is my write-up:

ENTIRE COOLING SYSTEM REPLACEMENT Tips and Tricks (Very Long, Enjoy!)

HTH...

[kurtdaniel]

One possible reason a car for overheating is that antifreeze is not circulating through the engine as it should. Antifreeze serves two purposes. It not only keeps the engine temperature level during the winter ( preventing the engine from freezing) , it also keeps cars from overheating during the warmer months..try changing radiator.

[d3ity]

Replace the resivour cap and the coolant expansion tank bleed screw, shouldn't cost you more than 25 bucks for everything shipped to your door.

Also make sure your current bleed screw is tight!

[H8.2.B3.U]

i had the same problem in my 01 530i sport turns out the water pump was on its way out n would play up every now and then replacing it with a steel one is best option especaily if you drive your car hard as i do , it is one of the weakpoints on the car , hope u get it fixed up =]

[tony moss]

check waterpump bypass pipes at rear of waterpump & engine.slow leaks are hard to detect. also change bottle cap.