Water pump confusuion - Page 3

80stech · #21 06-15-2022, 10:44 PM

OK I just put the pump back up into place and with the wiring harness unclipped it looks like the wiring would work out (even nicer) if the connector went to the housing end like the 4 zone pump has! That being said the u-tube video I watched should the harness tight with the none 4 zone pump exactly like mine was.

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80stech · #22 06-15-2022, 10:49 PM

Thanks for posting that! I did not have that info in my ETK. So it does look like maybe the 996 pump then is the older 4 zone version of the 925 (same housing).

pshovest · #23 06-16-2022, 07:23 AM

You probably know this but if you highlight the line that has the part number, right click and select supercession, you can see all the equivalent PN's with the latest at the top. Post a photo of your pump & cable connectors if you can. I'd like to compare to mine. I'm very curious if pumps are interchangeable. I love the X5, it's likely the last non-turbo Bimmer I'll ever have, but I'm also getting tired of changing water pumps.

80stech · #24 06-16-2022, 09:21 AM

Ok, I have it all back together but still up on the ramps so I'll get you some pics later of the connector and harness when I can (might be later today) . Maybe you could check the connector shell part numbers? It might be just a matter of changing the shell. I think the Mishimoto pump might be the way to go, have you looked at that?

BTW I can't see it taking 5 hours to change especially if you have done it before ?? Are you taking out the cooling fan ?

80stech · #25 06-16-2022, 01:03 PM

Here are a couple of pics. There was lots of wire for the harness once I pulled the clip out of where ever it came from!

pshovest · #26 06-16-2022, 05:03 PM

Yes, I remove the fan and take the pump and thermostat out past the radiator.
I kept the old pump that was replaced under the CPO warranty. Here's a photo of the connector. Looks like the connector is the same at yours. I haven't looked at any other pumps since I'm getting free replacements at FCPEuro. It sure looks like I could use the non-4Zone pump.

80stech · #27 06-16-2022, 06:23 PM

Yes, that does look exactly the same! I don't know why it looked more square in the pictures I saw. Should be no problem with interchanging them then. Good info!

I would still wonder if BMW has done anything to improve either of the pumps.

80stech · #28 06-17-2022, 12:24 AM

Here are some pics of the old pump dissected. As I suspected brushless motor and microprocessor controller but really cool is that the bushings and armature run in the coolant! There was a build-up of silicate on the outside of the armature/bushing coolant housing and I thought that maybe that was an issue but the pump seemed to turn freely and there was little or no wear on the bushings so more than likely a failure with the microprocessor or driver chips. The field and external connector is all spot welded so it makes servicing almost impossible but a person could tap into the field windings with a different controller if motivated. There has been huge improvements with microprocessors and drivers(most likely the problem) since these were built so I can't imagine that it would be hard to make an improved version.

andrewwynn · #29 06-21-2022, 01:33 AM

Enclosing the prime mover into the pumped fluid is the only way to make it leak free. All fluid pumps not made this way need to leak some of the pumped fluid out the prime mover shaft to lubricate the shaft seal. (it's why in old cars when the water pump fails it tends to squeal like a pig). The shaft seal fails and the fluid will get into the bearing and dissolve all the grease.

A sealed bearing inisde the pumped fluid solves this issue. And yes: very cool!

The better pumps will have a torturous path seal between the armature and the pump impeller to slow the fluid exchange between the motor and the pump.

The fuel pump is the same. Completely flooded design. Even though they are usually brushed motors! Seeing all the electrical contacts which tend to spark in open air bare and open to the environment still is freaky to me; that's what brought down flight 800!

andrewwynn · #30 06-21-2022, 01:37 AM

I did a similar tear down on wife's e53 aux coolant pump. It's nearly identical design just much much smaller.

I probed around on the board with my oscope a bit and discovered one phase was not generating the correct waveform. I didn't spend enough time figuring out which component failed but it wouldn't have been that difficult to do so. Very good chance just a blown cap or transistor.

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