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Water pump running on after ignition off & draining battery - help please

Discussion in 'A3/S3 Forum (8L Chassis)' started by The Doctor, May 18, 2011.

  1. The Doctor
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    The Doctor Well-Known Member

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    Help again please!

    I know that my battery is on its way out, hence my post yesterday evening. However I now think that I have another problem with the water pump running on after the ignition is switched off (the little one above the alternator at the front of the engine bay).

    I know that this should run for a period of time after the ignition is switched off, but the story goes like this:

    1. Yesterday morning the battery was flat (hadn't driven the car for 4 days), so I re-charged it out of the car for 4 hours during the evening & re-installed it before going to bed.
    2. This morning the car started fine and I drove to work (12 miles) without any problems. So the battery clearly held its charge overnight and I thought the problem was just that it had lost charge sitting on the driveway for 4 days.
    3. However, when I went to leave work this evening, the battery was dead again, only just turning the engine once. When I popped the bonnet to jump-start it, I could hear the water pump just about ticking over - but I had not driven the car for 8 hours! Seems to me like the pump is intermittently keeping running rather than cutting out.

    Anyone else had this? Does it make sense to you?

    Until I can get it looked at I'm thinking of just either removing the fuse (I think it's #16 in the handbook?) or removing the electrical connector directly from the pump when I park up and re-connecting before I start it up again. Do you reckon that'll be OK?
    Last edited: May 18, 2011
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  2. Sandip
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    Sandip Well-Known Member

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    Won't be the after run pump causing your main issue, mine runs even if i just turn on the ignition then turn it off, don't have to drive the car.

    It could be that your alternator is not fully charging the battery in the first place, personally though i think your problem will be sorted once you get a new battery :)

    I've had it where my car was ok, no starting issues, went to fill up fuel, walked back to the car, go to start the car and nothing. Batteries are buggers sometimes
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  3. s3dave
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    s3dave TFSI Hybrid

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    Agreed^^ the pump will run if you put the ignition on and off....hot or cold
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  4. The Doctor
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    The Doctor Well-Known Member

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    Ah, good point chaps, that makes sense. I did turn the ignition on to try to start the car when I left work, so that will explain why the pump was running when I opened the bonnet.

    So I'll just replace the battery. Problem is, the Bosch Silver one that's recommended for the S3 8L (which I've bought) is 3cm too wide for the tray! So I guess I'll be borrowing the missus' car again tomorrow and taking the battery back tomorrow evening. What joy.
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  5. Sandip
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    Sandip Well-Known Member

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    Never seen a bosch silver battery but if it's possible could be worth checking if the cells aren't dry
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  6. AndyMac
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    AndyMac Moderator Staff Member Moderator

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    That's Halfords for you
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  7. The Doctor
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    The Doctor Well-Known Member

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    Er, it was just a knackered battery.:blush:

    The HSB096 was the recommended Bosch Silver battery on various online sites, not only Halfords. Having looked at my friend's pre-facelift, I think it would fit because he doesn't have the plastic case around the battery whereas on my 2003 8L it wouldn't fit. In the end I bought a Bosch Silver 027 S5005 which fits perfectly and is the same dimensions as the original.
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