I just got a 2000 A6 for my wife today but it has some issues I need to try and get corrected for her. I got a A6 2.8 Quattro, it seems to have a cooling system problem where it starts to overheat after about 20 mins of running. I has had a recent flush and the recovery tank was replaced by the PO. I just went through a complete cooling system overhaul on my BMW so it is not anything that scares me I am just looking for some info on common things I can look at first.
Is this a common issue with these cars and if so what would your guys suggest as far as replacement parts. The PO said a "mechanic told him it could be the thermostat or worst case a water pump but I am not convinced his mechanic was familiar with Audi products. I had a similar run in on my BMW from a guy who told me my car had blown head gaskets but it turned out to be a valley pan leak. Any tips and info would be most helpful. I do my own work and have no problem getting my hands into most projects. Thanks in advance

 

Pressure test the cooling system to see if there are any leaks that could be allowing air in, thus impeding flow of coolant or allowing the coolant to boil in the engine and evaporate and escape through the overflow port on the bottom of the expansion tank.

Verify whether or not the top and bottom radiator hoses are similar temperatures after moderate driving. If the bottom is much cooler than the top, this might point to a lack of coolant flow/thermostat stuck closed.

Also check to see what color the coolant is. It should be the pink-ish G12/G13 coolant and not the yellow/green stuff. When you mix the yellow/green stuff with the G12/G13 coolant it begins to turn into a tacky like substance and will really wreak havoc on the cooling system. If that's the case, set aside 2 hours or so to perform several coolant flushes using distilled water.

If none of the above turn up anything suspicious then you can start looking towards things like a head gasket allowing coolant to be burned in a combustion chamber.

The good news is that nearly the same amount of work is involved in doing either the thermostat or the water pump.

 

Thanks will check that out, I can say the coolant is blue/green in color so I know a flush is in order.

 

I am also in need of good sites for parts and information. I need to get a service manual for my car and would like to search the VIN and see what the equipment installed from the factory is. I know with BMW you can do a VIN check and it will give you everything about where it was build and dates.

 

Check this out for decoding your VIN:
VIN Decoder - AudiWorld Forums

I've never used it before, but I've heard many people having decent luck with it.

For parts I would recommend either ECS Tuning or FCP Euro. ECS seems to be pretty good for the more obscure parts, where as FCP is better for suspension components. I will say FCP's support and customer service is pretty damn good. I've had to ask them to identify a part for me via a picture and special order me said part. They were able to identify it and order the part for me in about 10 hours. Amazing.

As far as a service manual, it's difficult obtaining one. You might be able to buy a knock off one on Ebay for about $20 USD.

To be honest, I have a service manual for The C5 and B6 platforms and I've maybe used it once to determine torque specs. They're good to have as reference materials, but the bulk of my knowledge has come from hands on experience as well as through these forums.

 

I think I am going to take up the task of replacing the water pump and thermostat. Doe anyone have a list and/or suggestions on what all I should replace while I have the front end apart? I found a Timing kit at rockauto that included a water pump but not sure if I need anything else. Thanks

 

Ok can update hat I have found out about my overheating issue. I hooked up my OBD2 scanner toady and ran the car down the street, less then 3 miles round trip, the car reached a temp of 245f and the aux fan never came on. when I got back to me house I checked the upper and lower radiator hoses the top hose was much hotter then the bottom. The gauge on the dash did not go all the way to the hot line and the car did not give any other warning. I am trying to come up with a list of possible solutions. Any experiences you may have to help will be most appreciated

 

This sounds like the water pump is not circulating coolant through the engine because either a stuck thermostat, the incorrect coolant has gummed up the coolant passages and has halted the flow of coolant, or perhaps the water pump itself is failing and beginning to free wheel.

 

Ok, I also discovered that the Aux fan does not come on at all even with the AC running.

 

Is this the fan in front of the condenser? (IE Is it the fan closest to the front of the car?)

If that is the case, then the next thing I would go is apply 12v directly to the fan itself to determine if it runs or not. If it does work with 12v supplied right to the fan, then you need to start looking at the fan control module as they are known to go bad.

The fact that this fan is not working doesn't necessarily mean that it's the cause of the overheating condition, however it will eventually need to be addressed.