1997 Dodge Ram

Heater problem
1997 Dodge Ram V8 Four Wheel Drive Automatic 116000 miles

I have no heat? I changed the t-stat, pulled the hoses off the heater core and put a water hose to the heater core and water comes out, so it is not blocked. There seems to be little flow to the heater core cause every now and then I can here a trickel in the core. There is worm air if I keep the fan on low, but on any other speed it blows cold. I am sure the flap that moves from cold to hot is moving, I checked that too. The truck does not over heat. I am lost on what to do next. Any suggestions?
December 1, 2007.

Dec 25, 2007.
You could remove the hose on the right side of the pump that has the tube going into the pump itself. Put a hose on the tube from the pump and plug it/pinch it, etc. Then run the other to a clean bucket. Start the engine and see just what the flow through the core is? If bad you can flush both ways going through the pump, there maybe build up in the inlet line to the heater core.( The one to the right of the thermostat housing). If no flow or very little could be pump, but I have seen radiators partially clogged cause low heat to but they usely come with overheating issues that you don't have.

Dec 25, 2007.