# Noise from Aux water pump



## david924s (Feb 3, 2016)

I recently had the coolant system pressure tested, coolant drained and replaced, new thermostat, and aux water pump fitted (new from Audi) as well as a new Audi heater matrix and AC drain and refill.

My question is when I first turn on the ignition so car cold ignition lights on but not started I get a weird groaning sound from the front of the engine which sounds like a pump running badly, you can hear the groaning going up and down in cycles.

If I start the car then I can still hear the noise with the engine running if outside the car and bonnet up but it will stop after a few seconds, if I then switch off the engine so car still basically cold I get the same (if slightly quieter) groaning sound from what seems to be the aux pump area (front lower part of the engine under dip stick area.

If I run the car until warm then I get no groaning either on ignition (not running or after running and switched off) just the normal sound of the aux pump cooling the turbo for around 10 mins.

Is this normal, or have they fitted a duff new Audi aux pump or is there some pipework connected badly, I'm presuming there is only two hoses on this pump inlet and outlet with the coolant exit the turbo going back into the circulation system.

Just wondered if anyone had the same issues before I go back to the garage and complain (problem is it does not do it when warmed so I would have to leave the car at the garage to let it go cold to reproduce the noise.


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## poor1 (Dec 28, 2011)

It could be that the pump is touching something and you are hearing the vibration.

The obvious course it to take it back to the garage that fitted it.


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## david924s (Feb 3, 2016)

I agree obvious to take it back just wanted to check if they were generally noisy as standard suspect not so back to the garage


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## David C (Apr 15, 2013)

I thought the aux coolant pump only ran after the ignition is turned OFF.

Runs for 10-minutes after ignition off under control of the fan control module.


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## david924s (Feb 3, 2016)

David C said:


> I thought the aux coolant pump only ran after the ignition is turned OFF.
> 
> Runs for 10-minutes after ignition off under control of the fan control module.


That is something I wondered as mine seems to run as soon as the ignition is turned prior to starting the car, or at least I am assuming it's that certainly not the fans due to AC being on as that is off. Noise is coming from the front of engine under dip stick area, need to take some covers off and have a good look and feel around to check it's the Aux pump.


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## poor1 (Dec 28, 2011)

They are designed to dissipate the heat once the engine is switched off. I would be interested to know whether they do actually run for the whole time the ignition is switched on and the engine running.


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## David C (Apr 15, 2013)

poor1 said:


> I would be interested to know whether they do actually run for the whole time the ignition is switched on and the engine running.


Wouldn't have thought so when there is a perfectly good mechanical pump circulating the coolant far quicker than the tiny electric one.

On my V6 it only runs after ignition off. Very quiet but definitely doesn't run until it is turned off.


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## david924s (Feb 3, 2016)

I will check at the weekend as there is a definite groaning sound like a pump running with only the ignition on but car not running and not having run so cold, like I said no the fans as they are definitely off, if I run the car for a few seconds I get the same noise when turned off and it runs for 10 mins so assumed it was the aux pump both times. May be a fault in the wiring something else to check


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## Hoggy (May 8, 2002)

Hi, After-run pump runs for 10 mins or so when Ign ON & then OFF when engine hot or cold, but very quiet on mine & can't hear it with bonnet closed.
Hoggy.


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## David C (Apr 15, 2013)

Hoggy said:


> Hi, After-run pump runs for 10 mins or so when Ign ON & then OFF when engine hot or cold, but very quiet on mine & can't hear it with bonnet closed.
> Hoggy.


So it should never be running if the ignition has only been turned on.
(not sure what happens if you turn it on, then off, then on again)

I can only just hear mine, most people won't hear it at all if there is any background noise.


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## david924s (Feb 3, 2016)

I will have to check what it is or take It back in as it is definitely making a groaning sort of noise when key just turned in ignition so lights on but not running and engine cold, not ran previously. Only seems to do it when car is cold or not been run and seemed to start right after the run on pump was changed which is why I suspected that.

I can just disconnect the pump wiring and see if it still makes the same noise to rule it out quickly when I get back home.


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## Hoggy (May 8, 2002)

Hi, Just checked & after-run pump does run with cold engine & Ign ON.. Ign Off & pump ran for another 10 minutes, so perhaps it does continue to run when engine on, but so quiet unable to hear it. More bubbly sound with cold engine.
I'm not starting my TT up just to check.
Hoggy.


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## david924s (Feb 3, 2016)

I think on the earlier Quattro's the run on pump only ran after engine reached a certain temp (110c) but the TT runs regardless when the engine is switched off after running regardless of temp.

Mine runs with cold (not run engine) key turned to lights on dash but not started like Hoggy mentioned, as well as when switched off after running, which I do no think is correct, no reason to run pump if engine and turbo has not been on but I will disconnect the pump and see if the noise is still there (then obviously not pump) but does seem to be the run on pump running regardless of whether the engine has run or not i.e. cold morning turn key to pre-ignition position and noise comes on like pump running, start engine and it seems to keep running although hard to tell.

So problem would seem not to be if it runs or not but the noise it makes which if it is the pump is not healthy (for a brand new pump) wonder if the garage kinked the hoses, causing a flow restriction weekend job I think.


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## Hoggy (May 8, 2002)

Hi David, Your thinking is wrong, I've had my TT from new almost 15 years & aux pump runs when Ign On whether engine hot or cold & when Ign turned off it runs for another 10 minutes... Audi systems are rather strange sometimes. :? 
Hoggy.


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## infidel.uk (Feb 21, 2015)

after run pumps are for pussies, lol

the amount of turbo cars ive had in the past, always been fine without one, but then i never use any boost for the last 5 mins driving, and it helps.

flame away guys


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## Hoggy (May 8, 2002)

Hi, Driving with no boost for last 5 minutes is also for pussies. :lol: :lol:  :wink: 
Hoggy.


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## david924s (Feb 3, 2016)

Got back to UK last night so went out this morning, ignition on but car not running, definitely cold not run engine, once key turned and Ign lights on the noise was from the run on pump as I could feel it almost sounds like an empty cavitating pump but the hoses seem to be connected right with no obvious kinks. Took a video of the noise which occurs as soon as the ignition lights are on and also continues when the engine has been run and turned off, but cant upload. Car goes back to garage next week for investigation and hopefully fixing. If I get chance at the weekend I might remove one of the hoses and see if there is any water in the pump or if it is air locked.


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## Hoggy (May 8, 2002)

Hi, Confused me now :? .
Ign is not ON until key turned & dash lights are lit. Pump then runs whether engine hot or cold & runs for 10 minutes once Ign off. Other than the the extra noise, all appears normal to me.
As I stated mine sounds more bubbly when coolant cold than when hot, but still very quiet & can't hear it with bonnet closed.
Hoggy.


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## Madmax199 (Jun 14, 2015)

Hoggy said:


> Hi, Driving with no boost for last 5 minutes is also for pussies. :lol: :lol:  :wink:
> Hoggy.


Well said Hoggy, exactly my thoughts. The after-run pump is a great concept and works very well!


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## Madmax199 (Jun 14, 2015)

David C said:


> poor1 said:
> 
> 
> > I would be interested to know whether they do actually run for the whole time the ignition is switched on and the engine running.
> ...


I wouldn't totally underestimate what the "tiny" after-run pump can do. I have done a few experiments to see what they're capable of. Well, these little suckers pack a punch for their size. They move several gal/min of water (zero head pressure) -- and routed to the block instead of the turbo, they greatly affect the flow through the system. I wouldn't run one in place of the main water pump but also wouldn't say they're insignificant in terms of flow comparison. At one point (before I sorted the TT's high track coolant temperature) I had plans to run a pair of after-run pumps, one to the turbo and one to aid the block flow as a secondary pump. I abandoned the project because I came up with better solutions, but I still have my after-run wired on a toggle and have it pumping continuously when racing. Great little pumps! :wink:

After-run pump going to a 1.5 gal of water in no time (zero head pressure)





Normal coolant return flow





Return flow with after-run re-routed to the block


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## david924s (Feb 3, 2016)

Hoggy said:


> Hi, Confused me now :? .
> Ign is not ON until key turned & dash lights are lit. Pump then runs whether engine hot or cold & runs for 10 minutes once Ign off. Other than the the extra noise, all appears normal to me.
> As I stated mine sounds more bubbly when coolant cold than when hot, but still very quiet & can't hear it with bonnet closed.
> Hoggy.


Key in ignition lights on but engine not running, run on pump is running as I understand it should, makes a dreadful groaning noise like I said as though there is no water in it, run engine until warm and pump is less noisy but still load enough to hear from a distance and runs as it should for around 10 mins. My pump also seems to keep running while the engine is running but more difficult to tell. Problem is the noise it makes like I said maybe an air lock in the lines or a dodgy pump, going back to garage that fitted it next week so let's see what they discover. As a precaution I am letting the car engine run on idle for a while before switching off in case this pump is not actually moving fluid around. It is so load I can actually hear it from inside the house with the car on the drive.


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## david924s (Feb 3, 2016)

Car back from garage today, another new Audi Aux water (run on pump) fitted and no more groaning when the ignition is turned and much quieter when running. Hope this one lasts previous genuine Audi item lasted around 1 week.


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## poor1 (Dec 28, 2011)

david924s said:


> Car back from garage today, another new Audi Aux water (run on pump) fitted and no more groaning when the ignition is turned and much quieter when running. Hope this one lasts previous genuine Audi item lasted around 1 week.


I trust it didn't cost you anything


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## Jez xbx (Oct 24, 2014)

Pretty sure mine runs with ignition on and cold engine?
APX 2000 Quattro 
(Several flattened battery episodes lol!)


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## david924s (Feb 3, 2016)

poor1 said:


> david924s said:
> 
> 
> > Car back from garage today, another new Audi Aux water (run on pump) fitted and no more groaning when the ignition is turned and much quieter when running. Hope this one lasts previous genuine Audi item lasted around 1 week.
> ...


No charge garage were fine about it told them it was making a weird noise and they told me to take it in at next available slot, took it in Wednesday so they could check it out (had to let it cool to test it) then they phoned to let me know they had ordered another Audi run on pump which arrived yesterday morning so got a call saying car ready to collect that same morning. Can't fault either the garage I bought it from or the place they use for work (Falcon Engineering & Development Mbro) Car even cleaned with a mechanic outside waiting to explain what had been done.

Must say I am glad the car came with a warranty when I bought it, to date the cost of work including the second aux pump is over £1000 and that wasn't anything really engine related main costs were replacing the heater matrix and everything that entails with the coolant system.


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