well I let my buddy drivemy car (02 A4 1.8t) and what was a small coolant leak turned bad and the car heated up a bit. He clames about 3/4 of the way to the red mark. So I fixed the leak and am working on flushing out all the green coolant that was in there. I have filled the system with water and when I run the car to let the water cycle throughthe car gets up to temp and stays there but I cant get the lower cooloant hose to get warm at all. So I am thinking the thermstat wont open. Sound like it might be the problem or does the radiator do an amazing job of cooling down the water running through it???

 

sounds to me like a thermostat problem.....

 

Thermostat possible good chance the water pump

 

i've never seen an audi w/ green coolant.

we use the pink stuff.... and when the pink and green mix it creates a gel which is known to clog coolant systems.

 

yeah itll work but on every audi that ive seen that had it in there it eventually turned brown and looked like someone took a dump in your coolant tank.

 

SAudi is right, don't mix the green stuff with the pink coolant that our audis need.
But I'm a little confused... After fixing the leak, " the car gets up to temp and stays there ", this sounds like the thermostat is workikng. When t/s fails (usually due to over-heating) they normally stay in the open position, so the engine won't over-heat, but the coolant won't get up to operating temp.
IF the temp gauge goes up to the half-way point then the t/s is working, an open t/s means the gauge won't climb much past the " C " .

What are the symptoms, do you get heat from the heat registers ?