This sounds like a circulation problem Len - maybe the water pump is faulty, or the radiator itself is full of sludge? You did a good thing by checking the thermostat though - that would have been the first thing. So, flush the system out with water, refill, check that the heater works and see how it goes after that. The main radiator should get hot throughout its area if alls ok - I wouldn't mind betting that the bottom area remains cold.
John, May 2008
