i have a 2002 f150 with the 4.6. It would only get like warm heat but temp was normal. I put new water pump thermostat and flushed out the heater core. Put it all together ran it for thirty mins with reservoir cap off to get air out. Still no heat. Temp stays in normal range. Heater hoses don’t get hot upper radiator hose gets hot

 

"heater hoses don't get hot".......... that's the problem. Need to figure out why...


could be the heater is plugged, could be heater is full of air, could be there is a shut off valve in the heater hose on the motor end........


Remove heater hose and flush with a garden hose... one thing I did is buy a TEE fitting at the Auto Store to splice into the center of the hose ( two hose clamps) and the third leg connects to the garden hose... has a cap and you can leave it there permanent...... or get temp fittings and clamp and blow thru... then get nipples to put the hoses back together.


with the TEE I can remove the garden hose cap and use it to vent air out of the heater since hose is up above radiator / motor/ and heater.

 

 

I flushed it with hose no gunk came out just antifreeze the heat now is like it was before I did all of this. It ran thirty mins with cap off to get air out

 

if the heater hoses are not hot, then you have no flow or full of air.


Look at the two heater hoses where they connect to the motor... "SOME" trucks had a shut off valve that was vacuum operated to stop water flow in the summer... Notice anything on the end of the hose besides the pipe nipple ?

 

No one hose comes off back of the motor the other comes off the front I take

 

I had this kit and it worked very well ... for awhile. When it got old, the plastic tee failed because the plastic tube cracked. The worm-screw clamps create a bulge which presses into the tubes and cracks them if they are plastic. I recommend replacing the plastic tee portion with metal and replacing the clamps with good ones similar to the type used on fuel injection lines. In theory this is great. Maybe you could find a similar setup at a hardware store in the outside spigot section of the plumbing department. This kit has been around for about 30 years.

 

A tip:
When clamping a hose over a pipe that has a ridge, place the clamp just 'after' the ridge 'not' on it.
The ridge is there to help keep the pipe from blowing off in addition to some seal.
The clamp and it's area can't normally get by the ridge to allow it to blow off.
Good luck.