Hello
My Father has a 1985 244GL and the heater blows hot air for a bit and then the more he drives it, it goes cold. If he stops in traffic the heater blows hot again and then goes cold again when driven. We replaced the thermostat and it was still the same. The temperature qauge is normal. A few weeks later the water pump went so we replaced it. Still no improvement. The pipes to the firewall get hot and there is no air in the system. Could it be the heater matrix even though it does work sometimes? Or could the new thermostat have gone as the water pump died and drained out all coolant. No damage was done to the head.
The engine is a B230A carbed. Any ideas? Many thanks KYLE123.