BWatson
As was already mentioned, probably air in the system.
when the system has been completely drained this is what I do...Raise front of car, disconnect "head to firewall" heater hose at firewall, wire up the end, Pour coolant into the upper radiator hose (disconnected at the radiator so its going into the eng) till it comes out the heater hose. reconnect everything, Start the car, turn on the heater full blast, when heat comes out your "home free"
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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug
"Lifes too short to drive a boring car"