Hi i was just wondering if anybody knows if the water in the expansion tank of my Audi coupe B3 is suppose to be cold when the engine is at the operating temp? The water is flowing through the system fine and warm everywhere else in the system. Everything works as it should but the expansion tank is always cold. There is plenty of pressure. My gut feeling is it should be warm and i think it always has been on other cars ive owned. Could anyone please help? Thanks Ian!!!

Hi, some cooling system designs have a single outlet from the expansion tank and on these the tank takes a while to get warm because there isn't any flow of warm coolant through it.   Other designs have more than one pipe connected to the tank.  For example some have a small pipe from near the top of the radiator that connects to the expansion tank so that any air in the radiator will bleed out automatically.  So just check how many pipes are connected to the tank - if there's only one connection the tank will tend to stay cool, although it will get warm eventually due to conduction.     Regards Clive