# Coolant leak 2001 A6 2.7T Quattro



## expated (Oct 10, 2007)

I have a 2001 A6 Quattro 2.7T with 85k miles. Over the past 2 two years I've noticed it losing about half an expansion tank of coolant fluid a year. I've looked for the leak but I can't find anything! Needless to say it’s pretty mechanically packed in there.

Today I actually noticed a small puddle of the expensive pink G12 stuff on the floor. Haven't had chance to dig any deeper yet though. *Based the groups expertise is there a common failure or leaking location I should focus on?*

Your support would be greatly appreciated!


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## nuGGet_puFFer (Nov 25, 2011)

I would bet that it's your auxiliary water pump.


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## expated (Oct 10, 2007)

I would bet that too. Performed a pressure test. Applied 15 inch pounds was down to 13 inch pounds after 15 minutes (nothing major in my book). I think it leaking slowly when it goes into after run cool down. At this point in time I'm not going to worry about it. The replacement of the aux pump is a royal pain in the ass.


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## GLS-S4 (Jun 6, 2005)

If it is the After Run Coolant Pump leaking G12 then you should be able to shine a small bright flashlight between the intake runners and see pink and white coolant track marks in the valley of the engine V, especially when looking between the cyl 4 / 5 / 6 intake runners on the Bank 2 side.

Just did mine for this very reason.


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## expated (Oct 10, 2007)

GLS-S4, thanks for the info. Did you actually do your aux pump or someone else. If yes, was it a pain in the ass?


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## GLS-S4 (Jun 6, 2005)

Check for coolant leakage in the V before assuming after run pump needs to be replaced. You have to look into the V as the leak track marks are not obvious without a good inspection and a lot of light.

Yes I replaced my APB engine code coolant after run pump myself as part of a 125K KM complete top end service meaning CAG's, cam seals, injector o-rings, N75 & N249, all vacuum valves, etc. My original pump was still working, but it was increasingly leaking G12 at the pump body o-ring between the wet & dry ends of the pump.

I would suggest before pulling intake to use compressed air to blow out the valley of the V as much as possible, to help prevent debris from falling into the heads during intake removal. You'd be surprised how much sand and dirt is sitting in the V and along the sides of intake to head mating surfaces. Plug the head inlets with rags as soon as intake is removed, be sure to clean all mating surfaces with scrub pad & brake clean spotless, install new intake gaskets in correct orientation and re-install intake following Bentley torque spec. Obviously now is the perfect time to install intake spacers if your interested. If your later 2.7T has the 4 port black plastic vacuum valve at the top left rear of the intake body then you may want a spare valve on hand as it tends to break easily due to brittle aged plastic. I also added a second clamp to each of the OE pump clamps, simply to ensure no hose clamp coolant leaks. I did not remove the intake completely from the engine meaning no need to disconnect all vacuum & fuel hoses if you don't want to, as I simply used two 500ml plastic pop bottles to prop up the bank 2 side of the detached intake body while replacing the after run pump.

Interesting to note late generation B5 S4 2.7T's had the after run coolant pump factory relocated to the right side front face of the engine. IIRC there was an Audiworld link including a relocation kit part number to relocate pump away from underneath intake. It is apparent Audi realized pulling the 2.7T intake to service the after run pump is not the best approach. YMMV and I only mention in case it may work for the C5 2.7T platform.


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## bradnic (Oct 2, 2013)

GLS-S4 said:


> Check for coolant leakage in the V before assuming after run pump needs to be replaced. You have to look into the V as the leak track marks are not obvious without a good inspection and a lot of light.
> 
> Yes I replaced my APB engine code coolant after run pump myself as part of a 125K KM complete top end service meaning CAG's, cam seals, injector o-rings, N75 & N249, all vacuum valves, etc. My original pump was still working, but it was increasingly leaking G12 at the pump body o-ring between the wet & dry ends of the pump.
> 
> ...


Best damn post for this job on the web. Thank you sir.


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