I've got a 93 400SEL that's running hot. I've replaced the radiator, fan clutch, thermostat, verified that the cooling fans are working along with the aux. pump. The engine runs great and has no water in oil or any back pressure in tank, so I'm pretty sure there is no head gasket problems. The next thing I'm looking at is the water pump. Even though it has no leaks or bearing problems, I'm concerned about the impellor slipping or not turning at all. I'm wondering if any body has heard of this problem before, and if you think this is possible. Thanks for any help on this matter. J.C.