I have a 1987 Sierra 1.6 Est. It has a SOHC engine. The Temperature gauge has started to read just below normal. I have been trying to sort out my heating system, changed thermostat, flushed system (several times!), I also had a leaking water pump...as a temporary fix for the leaky pump I put radweld in. I now know my matrix was the problem (I was trying to avoid taking it out if I could!) Havent replaced the matrix yet..All the pipes are hot..there is plenty of coolant (+Antifreeze) but now I am getting the low (sometimes it fluctuates) temp reading! I am wondering is it anything I have done? Or could it be the sender? I have investigated the electrical connections and they seem to be fine..is the temp gauge reading related to the heater matrix problem too? Please help if pos!!!

Martin.