Audi a6 overheating the water pumb was replace a year ago the car is not liking any where the car starts to over heat and when i put the heater on the tempeture neddle stay in the midle but soon *** u turn it off the car start to over heat????? the other problem that it has when u are at a light or a stop or in idole the car vibrates can u please help let me know what would it be >>???? dont have a job so i cant take it to the dealer anymore;( thankyou

The thermostat would not stop the heaters from getting hot . Is flush out the heater matrix make sure water flows nice and free . But I would be looking at the water pump and at the same time flush main radiator and heater matrix at the same time. The thermostat stuck shut will cause it to overheat but not stop the heat out of the blowers.

With the age of your car ... your thermostat could be bad (ie does not open when engine warms up)

You have air trapped in system , change thermostat , bleed air from system , let it run hot while adding coolant with blower full blast on all front and rear heaters .

It could be the thermostat or the water pump. Even if your heater core were plugged, the engine would not overheat from it, you would just have no heat. And if the thermostat were stuck closed, but the heater core was good, you would still get heat from heater while the engine was overheating. So it kind of points toward the water pump, unless neglect had allowed both the heater core to plug and the thermostat to stick closed. I mean neglect from not regularly changing the coolant every two years about.
Overheating can be as simple as a low coolant level, so you should check that, and check for leaks.
Before you go for the cost to replace the water pump, you should first have the system pressure tested, or have a compression test done to check the internal condition of the engine and to make sure you don't have a blown head gasket. Good luck.

I had no heat after replacing the water pump on my 96 Audi A6 quattro. After reading the last post, I found a bleeder on one of the hoses going to the heater core. I just turned it and it allowed the air to escape. Then I had heat.

I would suspect the thermostat has stuck closed. Drain the system, heater on hot, flush the system, replace the thermostat, pour in pure water and see if that cures the problem. If it does then drain the system again and pour in a 50/50 mx of antifreeze and distilled water. You also need to make sure the cooling fan is working and the water pump is circulating coolant in the system.

Most likely the thermostat has failed and is stuck open. It's a lot of work to change, and it's common on the 2.8L. Here's a pic of my car a few weeks ago when I changed mine (yes, you do have to remove the front of the car - no other way to do it):

http://farm3.static.flickr.com/2456/4026320040_32ef32e2d2_m.jpg

Copy and paste that into the browser. If you're near upstate NY, reply here with contact email address - I can do the job for you.

another difficult one to diagnose without car in front of me iam afraid ,could be anything from a head gasket to a partially blocked rad caused by no ANTIFREEZE ,try it again and turn the heater on max heat and fan on max and see if runs hot then if its ok ,let engine cool and put about 200grms of caustic soda in rad and run it for half hour ,let it cool and flush out the system with a hose pipe .then refill with water and try another drive ,if its ok then refill with antifreeze ,if its not try the caustic again .if that doesnt work trade it in quick

The hot water from your engine cooling system is not getting into the heater core. Check out the valve that admits water into it.