I just got a BMW 740il. It drives great, but it is overheating.
I first noticed water leaking at the neck of the expansion tank. It turned out the small tube was cracked so I replaced the expansion tank. I figured this was the problem.
The car did the samething. After about a half mile of driving the temp needle goes a little past halfway and water/coolant starts to come out of the expansion tank cap!
I took out the thermostate and put it in boiling water and nothing happend.
Is the termostate on these car electric?...should the thermostate have opend when I put it in the boiling water?
Any ideas? Thank You, Les Marietta GA