Okay, here is the story, 94 150, NO Heat. We have read through hours of posting. All great info but we still can not get any heat. Here is where we are at, New heater core, new water pump, radiator has been checked, new cap, 5 different thermostats, blend door has been checked, the controls change the air position (heat, def, vent, a/c). We have blown air through the heater core, intake manifold inlet and pump outlet. Both heater lines are getting hot. Engine temp is at 180F. What is left???

Please Help.

 

Are you sure the heater control board is working where you select heat, defrost, etc?I know it's not a Ford truck, but our 93 Mercury Cougar had the exact same problem and it turned out to be the heater control board. If you've replaced everything else, then that's probably the only thing left. Just a thought...

 

If both heater lines are getting hot..I'd say the heat is reaching your heater core...so it from the core to your vents that something is a muck...Control board or door in the venting system not opening.

 

Try reversing the heater hoses. One should be hot and the other should be a bit cooler once it passes the core. Or there is a blockage at your water pump heater outlet pipe.

kwing

 

The selector for the heat,vent,etc seems to work fine. Goes to vent,heat,etc.. Just luke warm air at best.

I can switch the heater core lines but this should not make a difference, the core is just a flow through, non-directional.

If I pull the water pump outlet and start the truck should I get flow? Or does the system need to be sealed? I would like to know I am getting flow to and through the core first.

 

You could put a garden hose on the heater hose going from the heater to the block and briefly pressurize it to see if water comes out the heater. Also back flush the heater core with the hose disconnected at the water pump. Maybe the hoses are gunked. Try running the engine momentarily with the outlet line from the pump to heater disconnected. You should see pressure. When you put everything back together fill the heater lines with fresh water and then connect the hoses. That way there will be less of a chance of air in the system.

kwing

 

Is your belt routed correctly? The water pump must turn counterclockwise or it will reverse the flow through radiator and all valves. I don't recall whether there is a winter/summer valve on that late a model, but some have had them. I'm having the same problem in my 1988 F250

 

before you start takein things apart and start getting ahead of yourself try adding more antifreeze/coolant to the raidator.

 

Radiator is full likewise with the over flow tank.Removing the hose of the water pump resulted in no water (flow wise) and the same for the manifold hose.

This pump is brand new and the truck has no overheating issues. I doubt the pump is rotating backwards but I will check to be sure.

Any thoughts??

 

Maybe a silly question, but when you replaced all these heater and water pump parts, did you by any chance run the engine with the heater fan on high and the heat on highest temp. with the radiator cap off. If there was an air pocket in the system this should allow the air to come out. Then top off if required. I think I read somewhere that about 15 mins. or so after reaching normal operating temp. should be long enough.
Just a thought.



guzzler96

 

On my 351W in my 88 F250, the fellow that put the belt on for me, had the water pump running the same direction as the engine (clockwise) This resulted in the water flowing into the radiator from the wrong direction. A 302 is a counter-clockwise engine, opposite a 351W small block. The belt should form an "S" around the drive and waterpump pulleys. Make sure the thermostat is hot enough or the heater never will get hot. Check with Ford for the hottest recommended for your application.