cooling fluid blowing off after a few hours of driving?!?!?

[imacwalker]

iv got the 2001, allroad 2.5tdi, its been doing great, although after a drive to the south of france, the engine coolant warning light came on , after having a look at the level it would apear that it has dropped, so we filled it up, took it out for a drive for a few hours, no A/C on and again in the following morning we were greated by the coolant warning level, again the level had dropped. we have had the car checked out, and the garage have said that the cap for the resivaour may be faulty, so that has been replaced, to no avail, the level is still going down, in france we had it checked by a audi garage they suggested that it might be a blockage in the radiator its self as, there is a blow off valve at the back of the resivaour, which is showing evidance of blowing off steam ,
whether or not the blockage is in the radiator we could not tell, and audi uk have not been able to find a fault, just that the car is boiling off its coolant, we reckon that there is a blockage in the radiator somewhere,


if anyone has had the same problem could you please let me know asap!. as it is increasingly worying

[04A4]

I haven't owned my Audi for long and i am still learning the system but in the previous cars that i have owned i have had a lot of cooling system/ overheating problems and the like.
I noticed that the Audis seem to have a sort of blow off valve on the bottom of the resivoir (sp?) and when it gets hot the hole expands releasing the excess pressure and steam.
Being that the tank is plastic, it's possible that it has expanded too far and it is no longer able to fully contract to normal shape...
You might try replacing the resovoir.

[cms_45]

I have read that there is a known issue with the reservoirs separating after stress/time. Usually with the timing belt, the reservoir swap is recommended by Audi I believe.