I had the identical problem. In my case, the fault was in the pump. The pump motor couples to its impeller through a magnetic clutch. With age, heat or whatever, the plastic impeller began to stick on it's shaft, the added load in turn increasing current draw on the motor. Then, whenever anything else on the same circuit came on it would overload the fuse. In my case, the solution was simple and free. I just disassembled the pump (easy) and reamed out the hole in the impeller until it spun freely. Problem solved. Of course, your mileage may vary. The pump is below the two solenoid valves on the firewall in line with a clutch pedal location. If your pump buzzes or vibrates noticeably in operation, then you may have the same problem.

Best regards,
Bob Hazelwood
'93 525i 5-sp.
Sharked, BL/ss'd, H&R + Bilsteins
BMW CCA (Boston)

> Subject: E34 Auxiliary water pump
>
> Hi all,
> I have a question regarding the auxiliary water pump. My auxiliar=
> y
> water =
>
> pump fuse (15 amp) keeps blowing after about a week running. I'm not sure=
> =
>
> of the exact function of this waterpump, however, I tried putting a 20 am=
> p =
>
> fuse and that one blows after about a week as well. Is it safe to run =
>
> without an auxiliary waterpump and how can I check to see what the proble=
> m =
>
> is?
> Right now I'm running the pump with a 30 amp fuse and it hasn't
> blown yet. =
>
> Is this safe?
> Any info would be appreciated
>
> Mario
>
> 1990 BMW 525I<
>
>