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E34 (1989 - 1995)

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  #1  
Old 10-21-2013, 08:32 AM
Vivien Vivien is offline
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Aux water pump? Is this why my car is over heating?

Friends, fellow bimmer drivers, countrymen....lend me your ears, and knowledge!
This weekend my car began to over heat. I've had a coolant leak for about a month that I could not locate. I've just kept the coolant full.

Saturday on my way to work it started to over heat and steam filled my cab. Upon inspection I could see the coolant rapidly leaking from the under side if the aux water pump, hitting something hot and creating the steam that freaked me out.

I know this must be replaced, but I wonder if this is a root problem or just a symptom of another. As alway I must fix this as cheaply and quickly as possible. My 95 525i is a daily driver.


Please! Help!
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  #2  
Old 10-21-2013, 12:39 PM
Vivien Vivien is offline
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I've pulled the pump off, and there is a square hole that is spewing coolant
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  #3  
Old 10-21-2013, 12:47 PM
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Quote:
Originally Posted by Vivien View Post
I've pulled the pump off, and there is a square hole that is spewing coolant
Between the pump body and the electric motor????
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  #4  
Old 10-21-2013, 12:53 PM
Vivien Vivien is offline
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Yes!?!?! I wish I could just tape it
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  #5  
Old 10-21-2013, 01:21 PM
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Plug it, connect the input on the pump to the input on the heater valves, bypass the pump all together.
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  #6  
Old 10-21-2013, 01:34 PM
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Quote:
Originally Posted by 95-540sport View Post
Plug it, connect the input on the pump to the input on the heater valves, bypass the pump all together.

Yes, the seal is out between the pump and the motor....
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  #7  
Old 10-21-2013, 02:09 PM
Vivien Vivien is offline
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If I by pass, my car won't read hot but the heater inside won't work, correct? This is the first car I've ever wrenched on, so I lack a lot of fundamental knowledge, but I'm learning
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  #8  
Old 10-21-2013, 02:28 PM
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Quote:
Originally Posted by Vivien View Post
If I by pass, my car won't read hot but the heater inside won't work, correct? This is the first car I've ever wrenched on, so I lack a lot of fundamental knowledge, but I'm learning
Depends, if you plug it, no heat. If you do as i said, the inlet hose on the pump, run it to the inlet on the heater valve, you will have heat.
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  #9  
Old 10-21-2013, 02:55 PM
Vivien Vivien is offline
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Thank you! Here goes nothin....quick fix until I can get a part
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  #10  
Old 10-21-2013, 03:21 PM
Vivien Vivien is offline
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Most parts I've priced are 150 to 200, is there a way to fix the pump on the cheap? The little fan thing is cracked
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  #11  
Old 10-21-2013, 05:21 PM
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I have a working pump i can separate from my old heater valve. Or you can go to a pick n pull like LKQ and grab one for cheap
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  #12  
Old 10-21-2013, 08:41 PM
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95-540sport,

not calling you out, i genuinely dont know

why is there an auxilary pump if your method works?
I can see it working in my head, but there must be a reason for the pump being there.
what is the disadvantage?
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  #13  
Old 10-22-2013, 03:58 AM
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I think the pump is there to help the flow of water, i had mine unplugged a while when i got the car, and was figuring out where wires went. I had heat but it took a bit to get warm, you should have heat but it will not really be hot until your car gets to temp and the thermostat opens and begins circulating water.
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  #14  
Old 10-22-2013, 04:11 AM
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Re: Aux water pump? Is this why my car is over heating?

The aux pump has nothing to do with cooling the engine. Like 95 said its just there to help get water moving through the core faster on cold mornings. Remember these cars are European and it gets pretty cold in Europe. My ford 5.0l truck takes forever to warm up but the bimmers ready in 10 min.
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  #15  
Old 10-22-2013, 09:23 AM
Vivien Vivien is offline
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If it only effects the heat in the car, why does it read that my engine is hot. Is that just a precaution?
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  #16  
Old 10-22-2013, 01:59 PM
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Bleed the air out of your system.
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  #17  
Old 10-22-2013, 02:18 PM
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Quote:
Originally Posted by M540FELLA View Post
Bleed the air out of your system.
He can't its spewing coolant out a hole in the aux pump, that is why i suggest bypassing it, and then he would need to bleed. Or if it is the gasket in the pump pull it off, separate the halves, and put gasket sealer on it to fix it.
I dont understand why the 540 self bleed and others do not, just a strange tid-bit
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  #18  
Old 10-22-2013, 02:21 PM
Vivien Vivien is offline
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Um. She. That's why I ask questions like a dip****
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  #19  
Old 10-22-2013, 02:27 PM
Vivien Vivien is offline
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Quote:
Originally Posted by 95-540sport View Post
He can't its spewing coolant out a hole in the aux pump, that is why i suggest bypassing it, and then he would need to bleed. Or if it is the gasket in the pump pull it off, separate the halves, and put gasket sealer on it to fix it.
I dont understand why the 540 self bleed and others do not, just a strange tid-bit
I pulled the pump apart and the fan thingy is cracked down the middle as well, I don't know that I can fix the pump but I tried
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  #20  
Old 10-22-2013, 02:33 PM
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Well if you cant keep it from leaking, and leave it unplugged b/c of the broken fan, your only option is to replace or bypass it temporarily.
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  #21  
Old 10-22-2013, 02:44 PM
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Here is a little walk through to solve the issue until you can replace the pump.

You can see the overview of the lines here.


You will be bypassing the water pump, in my pics it is the old dry looking line in the center(yes now that i look at it it needs to be replaced)

Remove this line that comes into the center of the pump from the intake


And put it in place of this line that goes into the heater valves from the pump.(the old looking line at the bottom of the pic)


You are taking the line in the lower left of this image and replacing the line above it just to the right(the center line in the three line diagonal)


I hope this helps
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Last edited by E34ZombieHunter; 10-22-2013 at 02:46 PM.
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  #22  
Old 10-22-2013, 06:44 PM
Vivien Vivien is offline
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That's a wealth of help. Thank you. I'm starting to really worry my over heating problems are more than just this pump
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  #23  
Old 10-22-2013, 07:44 PM
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As said before when you get the leak stopped bleed the system. If any air is in it you will overheat. It you are worried begin to check other components after. Check the fan clutch(take a newspaper or magazine and try to stop the fan when the car is running, if it stops replace the fan clutch, if it shreds the paper, it is fine), check the thermostat, when is the last time the water pump(primary) has been replaced? They wear out quickly as the blades are plastic. First thing first get the leak fixed. And go from there.
You said it overheated b/c of the leak, why? B/c air got into the system and air has a lower specific heat(it heats faster than water),and it got hot quicker than the water would.
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  #24  
Old 10-23-2013, 12:06 AM
Vivien Vivien is offline
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Ugh! thank you! That was a very easily understood explanation And exactly what I was lookin for
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  #25  
Old 10-23-2013, 02:31 AM
Mamij Mamij is offline
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She just might be overheating due to a loss of coolant .

A coolant leak is perilous not because it introduces air, but because it vents coolant. And it takes a real barrel of air to cause the m50 to overheat. Air pockets are naturally moved out to the radiator and accumulate under the bleed screw without being circulated back, and is replaced in the engine by coolant drawn from the expansion tank which is why you often see it going down in gulps after draining and refilling the radiator or engine, which is normally when a *relatively* large amount of air is introduced into the system. Even that is never a problem if your cooling system components are in fine shape.

OP please check if you are short of coolant. Secondly. recommend you buy a new aux pump or put in a low mileage used unit. Winter is approaching and you really do not want to be without reliable heat. You seem smart enough and if you can't obviously see how the pump can be fixed once you're looking at it and if you don't get a solid reply about a good pump repair within 24 hours, buy another unit.

Bypassing is an idea but bmw would not have put in the aux pump there without good reason. Why split hairs over a $35 used replacement unit when winter looms? Cheap fix, one that you are clearly able to execute competently.

OP you should have the rest of your cooling system checked out as others have advised, if you have not already done so (do include your 2speed aux electric fan and its temp sensor, that is frequently overlooked). It's an old car, so nothing important should be taken for granted. That said, if you are methodical and determined to learn enough to be efficient, you will not tax your time and wallet unreasonably.

Welcome to the fest. A warm welcome.

Last edited by Mamij; 10-23-2013 at 08:36 AM.
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