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-   -   Horribly noisy auxiliary coolant pump (FL S8)! (https://forum.a8parts.co.uk/showthread.php?t=7247)

HPsauce 25th November 2013 08:47 PM

Horribly noisy auxiliary coolant pump (FL S8)!
 
Sadly today my pump decided to go into noisy mode, with a horrible high-pitched throbbing note that just got louder and louder.
So I thought - I know how to deal with that at journeys end, having done so before. Wrong. :angry2:

The wiring for the facelift D2 is different and the connector next to the pump that can just be quickly disconnected to silence it isn't there! :mad:

On PF there are two similar connectors (different colour coding) one of which is for the pump. On my FL there's only one connector visible, nicely held in a little plastic clip too! But it's not the one for the pump. :tuttut:

I can't believe the unit that the pump is part of is any different between PF and FL, so I'm hoping the connector is squirelled away somewhere not quite as obvious, but accessible. Does anyone know where and how to get at it?

Or is there a relay that controls it (logic says there must be from the way it doesn't kick in immediately on starting) and can that just be pulled? Again, anyone know if/where that is and whether it controls anything else?

The noise did reduce slightly on the return journey, but it's still highly irritating. After about 5 hours of it today I'm climbing walls! :-(

notorious 25th November 2013 09:36 PM

Watching this thread with interest as sooner or later I will need to change this pump.

HPsauce 25th November 2013 09:44 PM

The pump unit or just the electric motor?
I think there's some (not 100% complete) information on changing the motor in another thread - posted by IT IIRC.

notorious 25th November 2013 09:55 PM

pump, or motor or just bearing... whatever is needed to fix the noise.

HPsauce 25th November 2013 10:05 PM

Just disconnecting the power to the motor fixes the noise, with minimal side effects. :cool:
My problem is that I can't find the lead; it was trivially easy on my PF S8. :o
(there are two leads to the unit, it's the one with the dark connector that powers the pump motor, I think the lighter/beige one is for the valves - I've found that easily)

This is what Ian said about replacing the motor:
Quote:

Originally Posted by IT (Post 32455)
Its just the bearings on the motor. We've known people just unplug the motor to stop the noise (quite easy to reach the cables from the engine bay side) and the only thing that seems affected is the resting heater.... The pump runs continously, but the heating doesnt seem harmed by not having it running.

The motor is screwed on using two screws from memory, but these cant be accessed from the engine bay as the blower assembly is in the way.

By removing the glovebox, and then pulling back the carpet and acoustic foam insulation, you reveal the large square plastic cover which is held on by 4 hex nuts. Remove these nuts, remove that cover, and then my memory goes a little hazy, but remove what ever is under there to get reasonable access to the pump. undo the screws, remove it, stick another one in. +++


notorious 25th November 2013 10:36 PM

Thanks, I will do some research. Don't want to solve problem by disconnecting electrical connector though.

ELSA term of the unit is "pump valve unit". It consist of coolant circulation pump V50 and two heat regulation valves N175 and N176.

Coolant ciculation pump V50 will have two 1sq.mm. wires attached to it: red/yellow from battery via fuse and brown/green from HVAC unit with switched earth.

Interestingly, N175 and N176 valves are connected via 3 pin connector T3q (brown/yellow, brown/white and red/yellow) located in plenum chamber on right side where as pump V50 is connected 'directly' without any connector ...

HPsauce 26th November 2013 07:37 AM

Quote:

Originally Posted by notorious (Post 64864)
Coolant ciculation pump V50 will have two 1sq.mm. wires attached to it: red/yellow from battery via fuse and brown/green from HVAC unit with switched earth.

Interestingly, N175 and N176 valves are connected via 3 pin connector T3q (brown/yellow, brown/white and red/yellow) located in plenum chamber on right side where as pump V50 is connected 'directly' without any connector ...

Now that is "interesting" in a number of ways:
1. The 3-pin connector is there, very obvious. Same place as on PF.
2. There was a 2-pin connector in the same location on my PF S8 and ALL pictures of the pump unit show both connectors - each on a short lead!
3. Where is the fuse and is it ONLY for the pump (you know what I'm thinking)?

notorious 26th November 2013 07:52 AM

The fuse is not just for the pump of course.

I would make an assumption that the 2pin electrical connection is on the pump body itself, so it doesn't show as a separate connector in the middle of the loom in ELSA.

Here is picture of D3 unit: http://www.ebay.co.uk/itm/AUDI-A8-D3...item3f2b5ae0d6. On the left hand side of the picture the plastic motor chassis finishes with something that looks like an electrical connector.

I didn't find D2 picture from 2002 model car.

Goran 26th November 2013 12:05 PM

Originally Posted by IT View Post
Its just the bearings on the motor. We've known people just unplug the motor to stop the noise (quite easy to reach the cables from the engine bay side) and the only thing that seems affected is the resting heater.... The pump runs continously, but the heating doesnt seem harmed by not having it running.


This is what I like to hear!
Another useless thing to remove :)
I'm going to replace mine with a piece of coolant hose, when I can get round to it.

HPsauce 26th November 2013 12:13 PM

1 Attachment(s)
Quote:

Originally Posted by notorious (Post 64873)
I would make an assumption that the 2pin electrical connection is on the pump body itself

I've made some progress and indeed it is. +++
Must have been a "late revision" on the D2 as all the units ever pictured look like the attached photo, with 2 fly leads and large connectors.

Managed to follow the loom and find where there's a 2-pin plug directly onto the pump body. But it's a swine to get at and I can't even see how it's latched on, let alone get any fingers or tools anywhere near it. :(

But the 2-wire loom itself is neatly wrapped in Certoplast and quite accessible, so I'll be chopping into that some time in the next few days to break one or both circuits and "possibly" install a connector for "future use" (or maybe not :rolleyes: )


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