What does the additional water pump do????

[Kibokojoe]

Pulled the auxillary waterpump and valve tonight and cleaned it. Found out that the pump had a broken magnet and the cup that encloses the impeller is chipped. Looks like I will need a new pump. Servos/valves work great. I have noticed I don't have any power to the two wires that service this pump. What controls this power and what does this pump do anyway??? Does it increase the flow of antifreeze to the heater cores?

Please let me know

Thanks
Ken

[John in CT]

Yes, it's called auxilliary pump and as near as I can figure it is there so that when you are idling at a light or whathaveyou the heater core gets some nice warm coolant circulating so the cabin is constant temp. Mine started leaking lasy week and I took it out of the circuit, very east to do BTW and my heat works fine, go figure,

John
1995 525i 5 speed

[yaofeng]

With the popularity of BMW and the money it makes, the engineers in BMW can afford to get carried away. Does this electric pump make me feel warmer faster in the cabin during the heating season? I can't feel the difference. There are a few more items I think BMW also over engineered. The intermittent wiper stopping at a trafic light is one of them. I am lost to the point of this. Are they trying to save energy? I want my wiper to be moving all the time whetehr the car is moving or not. Why make the wiper stop when the car is not moving? Sometimes I think these guys in BMW have too much time on their hands with the money it rakes in from world wide sales.

[winfred]

some cars (e34s) the heat doesn't work worth a damn without the aux pump and others don't notice a difference.

The intermittent wiper stopping at a trafic light is one of them. I am lost to the point of this. Are they trying to save energy? I want my wiper to be moving all the time whetehr the car is moving or not. Why make the wiper stop when the car is not moving? Sometimes I think these guys in BMW have too much time on their hands with the money it rakes in from world wide sales

i liked the stopped moving wiper delay on my e34, i also liked the adjustable interville for the intermittent wipers, i am one of those *******s that doesn't want the wipers going anymore then they need to as they annoy me, people in other cars with their wipers on warp 9 when it's barely misting bug me

[Michael999]

Aux water pump helps with the heat when the car is just started.
Without this pump and the heater on full blast on a cold day, it will take about 3-4 minutes to get heat into the cabin.
No other car ive ever seen has it, and they seem to "flow" the heat into the car just fine, my e34 needs to heat up for the heat to reach the cabin without the pump.

The connector for the pump will only get power when the climate control is trying to heat, so set your fan on, set heat to the max, and the power for the pump should come on. (move the dials once the car is running to 'jog' the cars cc into activating)

Its on the same fuse as the horn btw.

[winfred]

mercedes has had them since the late 70s

No other car ive ever seen has it, and they seem to "flow" the heat into the car just fine, my e34 needs to heat up for the heat to reach the cabin without the pump.

[shogun]

Based on my file for training of service technicians IHKA automatic climate control system.

Purpose: an electric operated auxiliary water pump is installed to maintain the necessary heating water throughput at low engine speeds.

The aux pump is switched on when the outlet temperature on one heat exchanger has exceeded the value of 30 degree celsius after a new start and the control variable Yl OR Yr is above 30%. The water pump is connected when the nominal value potentiometer on the driver's side is set to the end position.

The aux water pump is switched off when the control variables Yl AND Yr drop below the value of 25%.

[E34-520iSE]

The aux pump is switched on when the outlet temperature on one heat exchanger has exceeded the value of 30 degree celsius after a new start and the control variable Yl OR Yr is above 30%. The water pump is connected when the nominal value potentiometer on the driver's side is set to the end position.

Sadly for UK spec owners like myself, there was no aux water pump fitted on cars with engines below M30B30. So you have to rev it to get the coolant/heat circulating - bizarre but true!

Cheers,

Shaun M

[DaveVoorhis]

Sadly for UK spec owners like myself, there was no aux water pump fitted on cars with engines below M30B30.

My M50B25 is fitted with the aux water pump. My M20B25 was not.

[E34-520iSE]

My M50B25 is fitted with the aux water pump. My M20B25 was not.

That's interesting - I wonder if it was a post '92 addition on uk M50'd cars? I saw a 1989 535 at a local breakers with the pump installed. Maybe it's time to mosie over there and remove it. I could really have benefitted with a quick heat blast when I was staying in North Wales earlier this week.

Cheers,

Shaun M