never have had much heat from the heater of my 62 544 took it all apart took out the mouse nest between the blower and the cab and thought that was it, my discovery is the water doesn't circulate to the core from the pump, the heater core hoses never get hot, even after the thermostat opens I assume the pipe running parallel with the block from the pump would feed the core, when I took the core out it had a little anti- freeze in it and I blew thru it seemed fine do you have to bleed the air? I have a inline after mkt valve in 1 line but it is wide open, ant thoughts would be appreciated 2tired

ron thanks for all the great info I have heat now it was just low, but air supply is weak fan is turning fine, just not adequate to keep up with the cold, your 544 heats well with stock system? thanks again

Robert;

I'm no expert on B16s, but pipe running from Wapu to back of B18 engine is the RETURN from Heater Core, by way of HCV...

Hot supply is from stubby pipe at back of Cyl Head, so if you're getting no flow at Heater Core, it's likely the Heater Control Valve is not allowing flow....but first, check Coolant level and assure it is adequate. Next, open" HCV and feel hose temp on either side to confirm flow. HCV and HC are plumbed in series, so any blockage in that path will prevent flow. Check and verify movement action of Temp control cable is really getting to HCV (sheath is not slipping, allowing lost motion).

See also: http://www.sw-em.com/Coolant_Distribution_Pipe_Notes.htm
Sw-Em tech article on Cooling Sys is not yet on-line, but it's coming...(so's Christmas!)

Good Hunting!