By the way, I just bought this car 1994 740i. There was this noise coming out of(what I finally found out what it was) the electric/addition waterpump. I noticed the hose that was supose to be coming out the front of it (the pump) and attaching to the firewall leading into the cabin, was missing so, I contented to spray some wd40 into where the propeller is (which finally stopes the noie): anyway, after attaching the hose there still wasn't any water being pumped into or threw the pump. I know it's suppose to help with the interior heating. Not sure though. Just wanted to know how to fix this problem with water flow etc or ? I heard alot of guys disscunect it all together. Any help is appreciated. Thanks.
Additional/electric waterpump problem on 1994 BMW 740i
There are two tubes running under the intake manifold from the water pump to the rear water jacket which has heater hoses going into the heater coils. What you described maybe some modification. Reconnect the hose add water to the water overflow container and run your heater, this should get water back to the heater coils. and the noise should go away. Good luck