e92 335i coupe suffered from battery drain, can anybody help?

[michaelscoff]

On March.6 when I start the car the engine fan started to spin right away, since there were no warning lights I proceed to drive home. After about 15 minutes drive the "engine too hot" warning light appears on the dashboard and I reduced speed and kept driving for about 3 minutes, the warning sign became red and I got a power loss. I pulled over for 30 minutes and start the car again with the fan still on and drove for another 5 minutes home. The very next day I towed the vehicle to my mechanic and he said the coolant pump was down.


The vehicle was parking at the shop for about a week waiting for a new coolant pump and bolt to arrive. When my mechanic was about to start the car he found that the battery failed on the car and it is completely dead, the voltage was around 3V. He proceed to replace the coolant pump and also replaced the battery.


After replacing these parts, I picked up the car after that and drove home with no problems, I did not hear the engine fan spin again. After a couple hours I started the car again and after 15 minutes drive the "engine too hot" warning light came back, I pulled over to a parking lot and took a uber to work. After work I drove the car home with no problem. The very next morning when I was about to start the car the battery failed again. Not even let me open the door.


Since the problem happened twice I have to get the car towed to the dealership and let you guys have a diagnosis what caused a battery drain with a newly replaced coolant pump.

The problem happened even before I had the new coolant pump replaced. So the cause is still an unknown. What I am thinking is the DME or some sensor does not let the car go to sleep after shutting the car so the coolant pump continue working cause the battery drain.

Dealer gave me a report and asked me to replace a whole bunch of parts which cost more that 3k. I dont know what should I do now, can anybody help me?

[Pelican Parts]

Has the alternator been checked? What codes did the car throw? Check out the link below to one of our site's DIY tech articles, hopefully it'll give you a good place to start troubleshooting. Best of luck!

http://www.pelicanparts.com/BMW/tech...eplacement.htm


-Dmitry