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Thread: Does this sound like I need to put in a new water pump?

  1. #1
    Join Date
    Nov 2018
    Location
    Milwaukee, WI USA
    Posts
    5
    My Cars
    2012 F30 335i

    Does this sound like I need to put in a new water pump?

    I believe the answer is yes, but before I drop the money, I thought I'd ask for second opinions. My symptoms match some things I've seen in searches that people said were fixed by replacing the water pump.

    In short, my pump runs with the engine off, when it has no reason to. This causes the battery to die. When I get where I'm going and shut the car down and lock it and walk away, after somewhere around 30-60 seconds the water pump will start running, and not stop. I have verified it is the water pump by opening the catch tank when the car has cooled off and there's a continuous rush of high speed water (enough to churn up the water in the tank).

    I have disconnected the battery at home, waited several hours for the temperature to come down (the outdoor temperature is in the 30s/40s *F right now...single digits *C) . When I reconnect my battery, after some delay (1 minute?) the water pump starts a low volume flow....and after another 30-60 seconds goes in to high flow (churning the catch tank again).

    I have not found/checked the relevant fuse as I can't figure out which it is and if it were a blown fuse, I'm assuming I'd have no pump at all. I similarly have not yet been able to figure out where the relay is to try giving it a thump / swap with another one. (My car, specifically, is a 2012, F30, 335i, no x-drive).

    I have gone into the secret menus and seen that my water temperature runs around 101 *C on the freeway. I don't think my oil is too far off (I know I checked after parking a little while and both were 91 *C)

    I recently changed the battery (registering via NT510) as the original was 7 years old. Last Friday, the battery was completely dead when I left work. I have 132,000 miles on the car and as far as I know it was running the original battery (7 years old) and water pump. I changed the battery when it was going flat knowing I didn't have another winter's life in it. The car ran fine for ~ 5-6 days before today when it was again dead after being left for only 3-4 hours.

    I bought my car as a CPO a bit over 3 years ago. I drive about 30K a year, so the car currently has 132,000 miles on it. Aside from tires, oil and brakes (which I've done) the car has been to an indy shop to deal with a valvecover gasket leak and oil filter assy leak.

    I'm basing my thought that this is likely a dying pump on the fact that other people have talked about similar behavior (pump running loooooong after engine shut off) being the result of water leaking into the pump's electronics. At this particular moment, I don't believe I have codes (Will hook up battery again in the morning and verify...but I didn't see any on the way home after a jump start).

    Thanks!

    T

    Thanks for input!

  2. #2
    Join Date
    Nov 2018
    Location
    Milwaukee, WI USA
    Posts
    5
    My Cars
    2012 F30 335i
    Pulled codes - only have a handful of low voltage / lost connection with module that I'd expect from the dead battery (and me disconnecting it)...CBS, Kombi, etc.

    I left the battery disconnected overnight. Hooked it up again this morning. Did code reading etc. etc....not sure exactly when it started but the water pump is running. Catch can flow is more than a trickle - it's enough to "froth" the catch can.

    Car hasn't been run in 14 hours. Dead cold. Oil/Water temp sensors in the hidden menus read 9C. No interior / exterior / courtesy lights on. Nothing on the dash. Trunk is dark. All doors / hood / trunk closed. Checked for free movement of all electrical items (mirrors, seats).

  3. #3
    Join Date
    Nov 2018
    Location
    Milwaukee, WI USA
    Posts
    5
    My Cars
    2012 F30 335i
    Well, changed out the pump & stat this weekend. The job would've been considerably easier if I had better working conditions. I backed into my garage, dropped the rhino ramps in place and drove up. The result was the nose of my car being about 6" from the door when it was closed (it was ~ 0* C here this weekend). Some of the work would've been much easier with more vertical clearance not to mention being able to use the space in front of the car rather than going in sideways.


    All seemed well when I was finished...will see if I have another sudden dead battery in the next week or so.

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