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.

[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%.

[Anton CH.]

I know that in some cars that lack the 2nd water pump increase bump up the idle RPM by about 200-300 when you turn on the heat.

[Paul in NZ]

My E34 has the fastest heat to occupants from cold start than any other car,I have had.I like the wiper thing too.If the rain is fairly light you dont want the wipers goung kerthunk kerthunk kerthunk at the traffic lights.Much better to have it go from slow to intermittent.I never have my wipers on fast

[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.

[leicesterboy15]

There are times when I think 'wow those wipers are a great idea' usually when the rain is fairly light. But when its heavy and you approach a junction or roundabout and your wipers stop i can be annoying, only way to override is to turn them to full?

I didn't realise the e34 had an adjustable intermittent time? Is this standard on all and manually controlled?

I never knew you could get instant heat in the cabin either, I'll try that on my way home tonight!

[Kibokojoe]

There are times when I think 'wow those wipers are a great idea' usually when the rain is fairly light. But when its heavy and you approach a junction or roundabout and your wipers stop i can be annoying, only way to override is to turn them to full?

I didn't realise the e34 had an adjustable intermittent time? Is this standard on all and manually controlled?

I never knew you could get instant heat in the cabin either, I'll try that on my way home tonight!
Sounds like bypass this pump is the ticket. I have to agree that the E34 heats up very quickly. Versus my 88 Honda accord which takes about 15 minutes on a cold day. Thanks for all of the help.

[632 Regal]

you should read the owners manual, there are so many things you will never even discover on these cars...

the wiper is set when you go from intermittant then to off...now go back to intermittant, the time you waited to turn them back on is now set to a different speed ;-)


There are times when I think 'wow those wipers are a great idea' usually when the rain is fairly light. But when its heavy and you approach a junction or roundabout and your wipers stop i can be annoying, only way to override is to turn them to full?

I didn't realise the e34 had an adjustable intermittent time? Is this standard on all and manually controlled?

I never knew you could get instant heat in the cabin either, I'll try that on my way home tonight!

[632 Regal]

power is only applied to shut the valves off and to run the motor itself, I think there is a fuse for it or something too.
I have noticed I don't have any power to the two wires that service this pump.

[Kibokojoe]

What is an owners manual. I was given this car as a gift from a friend. I am not going to complain if it didn't come with a om. I guess I should start looking for one, shouldn't I.

you should read the owners manual, there are so many things you will never even discover on these cars...

the wiper is set when you go from intermittant then to off...now go back to intermittant, the time you waited to turn them back on is now set to a different speed ;-)

[Kibokojoe]

Power to the servos but nothing to the aux pump. I am guessing there is some sort of temperature control on this pump.

[leicesterboy15]

632_Regal - that is great info, thanks. I will try that as well! Maybe I should read the manual!

[AutoXr]

The interval is adjustable, but it's a very dodgy procedure IMO. You need to remember the sequence of things you're supposed to do....I think it's turn them on, let it wipe once, turn it off again at the interval that you want to repeat, then turn it on again. Something like that. I rarely get it on the first try. What is wrong with a simple dial?

Regarding the cabin heat, this is the single biggest disappointment with my E34. I live in Northern Wisconsin where heaters mean something. This is by far the poorest heater in any car I have ever owned. Perhaps there is something wrong with mine. It works, just slowly and it's weak tempurature wise. I supposed I should do some diagnostic work before whining about it, but I've never been impressed with the heater in this thing.

[shogun]

Make a new thread with some more details, then we could recommend something, such as changing the microfilter etc.

[winfred]

not that hard, on then off in one motion and then turn them on when you want them to wipe


The interval is adjustable, but it's a very dodgy procedure IMO. You need to remember the sequence of things you're supposed to do....I think it's turn them on, let it wipe once, turn it off again at the interval that you want to repeat, then turn it on again. Something like that. I rarely get it on the first try. What is wrong with a simple dial?

[clindahl]

I live in NC where the climate is mildly cold for a BMW compaired to the north of the USA and Europe. I noticed that this past winter the heat was pathetic at idle and low speeds in the car and decided to troubleshoot. The Auxilary pump was deader than a doornail. I replaced it, flushed out the heater core and now have heat that is absolutely incredible. I didn't think a car could produce as much heat as this things does now :)

[Kibokojoe]

Most definately check out your heater system. My E34 will burn you out of the cabin in less than 10 minutes reqardless of the outside temp. I have heard the major culprit is the solenoid and pump orfices. I know with my honda it was the heater core. It was plugged big time. I hook a garden hose directly to the heater core and blasted it clean. I was amazed at the amount of mud that flew out the line. I used a connector from a prestone antifreeze flushing kit. This kit comes with a number of different sized fittings and it is designed to screw right on to a garden hose.

[AutoXr]

I don't know why I put up with it....oh yeah, my wife drove it all Winter. :)

It's ready for coolant replacement anyway. I think I will have the thermostat replaced, flush the system, and check the aux pump for proper operation. I'm sure I'll do a forehead slap when done. Oh well, I know the AC works....that's all that matters soon!

[JMI]

not that hard, on then off in one motion and then turn them on when you want them to wipe

The design is a crock of $hit ;). A real pain if the amount of rain fall is constantly changing.

Regards,

Jim

[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

[winfred]

i've yet to see a e34/32 without a aux pump


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