BMW 316 1988 Overheating/Cooling Problem

[jp2609]

Hi there, Please can anyone help me???
I have a BMW 316 Carb 1988 3-Series.
Slowely but surely the Temp Gauge Keeps moving to the Hot Position - i dont think the gauge is at fault though because it takes a while to get hot and it hets hotter faster when i am on the motorway. If it goes into the red and i dip my clutch on tickover and let the car glide for a few momwnts the temp drops and then when i let my clutch back out it eventually goes into the red again??? I have completely flushed out the cooling ststem and found no problems. I have by-passed the heater matrix as i thought it may have been blocked but was ok. I have changed the thermostat and even changed the temp sender and the problem is still the same so it seems obvious that the coolant is not flowing as it should. my model does not have an auxilliary electric fan fitted so i ruled that one out too. I dont think i have a problem with the head gasket as it seems not to get as hot when i use the car around town due to constant stoppi ng and slowing down. I reallt am in need to of some help. I read somewhere that the waterpump may be at fault due to having plastic fans but the coolant does still seem to be flowing. Can anyone help or suggest what it could be??? Cheers - John, UK.