kevinruswick

I have a 2000 A6 Avant Quattro with the 2.8L engine. There was front end damage prior to my recent purchase that was not even close to correctly repaired. I am trying to put back together correctly, including re-connecting several cut electrical wires. Here is the current one I am working on. I believe this may be an after-Run Coolant pump, but wasn't sure if this model actually had one. I think I had seen that some in warmer clients did have the after-run coolant pump. Anyways, the picture is from underneath the front right/passenger side engine. I believe alternator on left and secondary air injection pump on right. You can see connector and cut wires on the part I am asking about. If it is the after-run coolant pump, is this a critical part to keep operational? I had seen some info on the web that the after-run coolant pump on a non-turbo A6 2.8 isn't really needed and can be unplugged if so desired? So, I am just trying to figure out if I should get this re-connected. The main issue I have been having is with the auxiliary coolant fan running when it shouldn't be. I am going to be changing the engine coolant fan switch tomorrow, but was also curious if the AfterRun Coolant Pump connection may be part of the problem. Thanks for the help!

2.7Lturbo

i can tell you that not the coolant after-run pump... but what it is.... dunno let me break out the book!

kevinruswick

Thanks for looking into this. Just to make sure, it is the 2.8L not the 2.7L turbo engine. I have the Bentley Service Manual and the Electrical Wiring Diagram shows an AfterRun Coolant pump for the 2.8L ATQ engine code. the part in the picture shows the cut wires. I also have an un-connected 2-Pin Green connector in the cluster under the plastic cover near the power steering reservoir. Wire colors appear to be the same, so I was assuming this was the missing connection...

A6Gary

In checking ETKA 7, there is an additional water pump for fuel cooling for the non–turbo 6 cylinder ATQ and AHA engines. This pump appears to mount on the passenger side, so I'm guessing that is what you're looking at.

SloopJohnB@mac.com

So why don't you put 12v to it and see what happens?

AS for how it operates, if it's an afterrun coolant pump, it was probably set up for running after the engine was shut down (ignition off relay), temperature was above such and such, and a timer relay activated. At least that's how Saab turbos were set up to run the radiator fans...interesting that audi just runs the coolant pump. A positive coolant circulation rather than a thermoconvection setup.

Saab had a recurring problem with timer relays failing so IIRC by the 1988 model year the timer relay was eliminated and the afterrun coolant fans were just wired directly to the radiator thermostat...the fans would run until the radiator cooled down below the set point; Thermoconvection would move coolant through the system, especially the watercooled turbo lines.

FWIW, my old 900T fans would run for no longer than 10-15 minutes after shutdown on a 100F day. So the relay elimination never killed a battery w/o the timer.

My thinking was that wiring the afterrun coolant pump on your audi directly to the radiator thermostat wouldn't hurt, but the more I think about it I recall reading that these afterrun coolant pumps REVERSE the normal coolant flow with respect to when the engine is running. Therefore if the coolant pump were to run while the engine is running it would try to reverse the engine pump....one would win or would stall coolant flow and probably overheat the engine. This wouldn't be a problem with an ignition off relay.

OTOH, you'd probably be best off restoring the OEM wiring. Hope the coolant pump is still operable.

4Driver4

The wires to that afterrun pump are part of the harness that goes over the air filter box and down to the secondary air pump. Look at the lower radiator hose - there should be a sensor on it and the wires should continue to the aux water pump.