MosTT

My 2001 225hp quattro AMU engine develops high pressure in water hose that runs across in front of engine from upper radiator hose to a type of electronically controlled cylinder shaped device attached on the engine side of the radiator. It has another hose out the bottom of the cylinder device that runs along the passenger side of the engine and then down to the back of the engine to where I dont know. The pressure builds up after driving so that water leaks from the hose at the clamp. I replaced the clamp and later noticed the hose is rock hard after driving. I dont understand how that small hose can have pressure build up when the other hoses indirectly connected to it do not have the pressure build up. Is the problem the cylinder device, thermostat or something else?

MosTT

Found my own solution in the "old FAQ". The part is the after run coolant pump. See
https://www.audiworld.com/forums/sho...php?p=17142139