farina43537

My 08, 535Xi has a mind of its own. I’ve noticed that there’s a random motor that keeps tuning on. The car can be sitting in the garage and all of a sudden I hear a motor run. For any where from five seconds to a minute. Now I know what has been running. I am replacing the serpentine belt, pulleys and tensioner. Also the oil filter housing. After removing the oil cooler adapter I was cleaning parts and whatnot. Suddenly water shoots out of the engine where the housing was! Along with the sound of that motor running. So now I’m sure it’s the damn water pump. Now what?
PS: I know that I should have had the battery disconnected. Well it is now!

seanjordan20

And you're not waking up to a battery drain message? If the pump is cutting on that would drain the battery.

farina43537

I am getting the message regularly.

seanjordan20

You need to change the part and make sure the connector is clean

farina43537

Is there anything else that would cause this? I’m not very familiar with BMW’s, it seems more like a relay sticking. Then again with so much computer control there may not be a relay that controls the thing.

seanjordan20

The pump needs to be replaced if the connector/wiring is good. There is no relay for the water pump. It has 2 fuses and ran by the DME. Pumps are a common failure and a clue that it needs to be changed is the battery drain issue. Most search for days trying to find what part is draining the battery at night. Luckily it was an easy find for you.

donpb

Were there no water pump codes or were the DTC codes never read?

farina43537

I don’t have a BMW code reader. I do have access to one and I’ll check it out. Thanks.