Hey i bought a 528e one time for $225 cause "noone" could figure out why it overheated turns out the waterpump impeller had come off the shaft.... warmup car with water tank cap off look into tank at small hose leading from raditor is it "peeing"{should be}? also did u have this prob prior to replacing tstat? hope this helps. jeff Just did the thermostat on my 535is and still runnin on the hot side of the gauge.Bled system many times.flow seems to be good.The cluch fan seems a little week. I acadently hit while i was bleeding and IT stopped rite in my hand,is that normal or is it shot?it only seem's to cool down when the aux fan comes on. I have the bently on this car. I am just lookin for some addvise on where to start.