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E34 (1989 - 1995)

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Old 03-03-2011, 08:14 AM
Dawntreader Dawntreader is offline
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Location: Perth, Australia
Join Date: Feb 2010
Posts: 39
Mein Auto: BMW 323i E90 MY09
Running without an auxiliary water pump

I have removed the auxiliary water pump because it died. I am currently running without it at the moment. Would the lack of this in the system cause havoc with my flap motors in the heater. I refer to any earlier post of mine regarding problems with the aircon and heater giving odd results etc. Just need to know what issues this might cause me.
323i 2009 E90 MY09 Sedan 4dr Steptronic 6sp 2.5i - 67,000 and Red Crimson.
525i 1990 E34 M20 - 400,000 Km's and rockin'
Impossible is what humans do best
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Old 03-03-2011, 09:42 AM
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Bloody Arro Bloody Arro is offline
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Location: Highlands, Tx
Join Date: Aug 2010
Posts: 437
Mein Auto: 94 525i
It'll cause you to overheat. That's what happened to me and I got a replacement one for $75.
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Old 03-03-2011, 01:06 PM
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vixixlxxxix vixixlxxxix is offline
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Location: Torrance,CA
Join Date: Jul 2010
Posts: 333
Mein Auto: 2001 530i
I've been running with out my aux pump but it was bypassed and it hasn't overheated. PO had it bypass but i will have it fixed later on and have it back to its oem state.
BMW E34 540iA Alpine.
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Old 03-03-2011, 08:57 PM
cmgreensr cmgreensr is offline
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Location: wilmington DE
Join Date: Feb 2010
Posts: 53
Mein Auto: 95 540i
No, it's only job is to push coolant into the heater core. Has nothing to do with the flaps. I have mine bypassed and have no issues, actually even the heat works just as good as before. I figure the pump was dead when I bought the car and I didn't notice and didn't have an issue till it started leaking.
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Old 03-29-2015, 08:22 PM
arienfonfria arienfonfria is offline
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Location: Miami
Join Date: Mar 2015
Posts: 3
Mein Auto: BMW
Yesterday i my 1997 bmw 540i ran out of coolant. i checked the car and i realized that was a leak at the bottom of the auxiliary water pump(i think). i believe it might be a seal or something like that. i took off the aux water pump and the heater valve. Is this a common problem with the bmw's??? how can i fix it??
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Old 03-29-2015, 08:32 PM
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MeNoo MeNoo is offline
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Location: Rochester, WA
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Posts: 1,264
Mein Auto: 1990 BMW E34 525i
Thread from the dead FTW.
HELGA-90' 525i
Unnamed-98' 328i
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Old 03-29-2015, 09:28 PM
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TheEinstein TheEinstein is offline
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Location: Denver, CO
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Posts: 2,254
Mein Auto: E34 540i
It's probably safe to say it isn't a thread jack I suppose. As for your pump Arien, if it's leaking I think you're gonna end up replacing it. Pretty much all plastic as you can see, and there's no "stop leak" for that. I desperately tried a few things for mine, ordered new one just recently. If you can call it good news, I believe I found the best deal available when I bought mine. I'll link below, but you can bypass it for about $5 with a "T" or Y-fitting from auto parts store. Note, you will have full heat flow through cores with the y-fitting.

This link is for the valve assembly without pump
1995 E34 540ia
160,000 Miles
VIN# ...GF32404
Hellrot Red


My Basic Repair History (Edited 1/27/2015)

Ongoing comparison between two E34 540ia's

OBC4 Hidden Functions : Link
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Old 03-30-2015, 07:40 AM
Larrick Larrick is offline
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Location: Berkeley California
Join Date: Sep 2009
Posts: 1,140
Mein Auto: 1994 525it
The aux pump had been bypassed when we bought the 525i in 2009.
There has not been any problems.
The heater works fine…..but we are in California….I am not sure if I would
be saying this if I lived in the Adirondack mountains of New York again, where
I had to have a small electric heater plugged in to the engine over night
in order to insure that it started in the morning.

Heat convection in the coolant system will circulate the hot coolant through
the heater coils in the cabin.
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