A little heater help.

[70RedBlurr]

Have not been able to get heat out of the heater in my truck. Blows air but just not hot, I think one time I got heat out of it but that was it after that. I have played with the control knob with no luck. I have done a search in the forum and read that it maybe wrong heater hose connection and maybe some cable in side maybe out of whack. I figured I would start with the heater hose connections and eliminate that problem first. Here is a picture of what I currently have going on...



I also read that my heater core could be upside down. Starting at the heater core the fittings are 3/4" for the top and 5/8" for the bottom fitting. I have a fitting that comes out of the top of the water pump and the last fitting I have is on the radiator itself, and the sizes for those are 3/4" on the radiator and 5/8" on the water pump fitting. i have read connect the two sizes together and also skip the radiator and go into the manifold, but I have a temp sensor in that location. Any help would or clues would do and hopefully get me toward getting heat to the inside of my truck.

Steve

[john]

Inlet to the heater core should be 5/8 hose from intake manifold. Outlet from core 3/4 to water pump or radiator. your core is correct with 5/8 on the bottom. intake man. is the hot source.

[70RedBlurr]

John thanks for the help, but when I connect from my core to the intake manifold where do I move my thermostat sensor to? You can barely see it in the picture but the port to on the manifold where the sensor is, is right nehind the alternator.

[10pointgmc]

should be a spot on drivers side of block toward the front for temp sensor

[Beachcomber]

I just did my core and I put the big pipe on the bottom.
I used a thermostat housing with the hole for the temprature sensor.

The top hose goes to the intake manifold and bottom goes to the pump.

[hounddogs!]

If you have airflow but no heat, there's no coolant going to the heater core. (assuming that cable and arm controlling the deflector is working) Do you have clear flow from one side of the heater core to the other?
Functionally, the air that you're warming doesn't care which direction the hot coolant is moving.

[swamp rat]

I think you have the long water pump, On my truck with the short water pump I have the temp sensor going to the top port of the water pump, and where your sensor is on the manafold is where the hot water exits and goes to the heater core. From all i have read the inlet hose is 5/8 in and the exit is 3/4 also.

Now heres where i get confused, according to all i have read in these forums and i have searched all over this place, the inlet on the core (5/8) should be on the bottom so the water fills from the bottom to the top then returns to the radiator, on my truck the 5/8 inlet is on the top but i have heat. I have no idea if these heater cores can be flipped end for end.

EDIT: Also get under the dash and follow the cables from the heater control, to make sure everything is functioning properly, move each lever fan, defrost, temp, and watch what is activated, you can see if each lever is moving the proper lever in the heater and that there getting moved all the way or only part way.. i recall when i replaced my control I had all the cables unhooked and had to send in the core to get the new one, then i had to remember what went where, then the clamping had to be done correctly to get full throw on the actuation levers on the heater..

[PanelDeland]

I flipped my heater core.It works fine.I just didn't like the hoses crossing under the hood.Looks neater this way(to me YOMV).While you have it unhooked take a hose and flush water thru the heater core.If you get good flow then the core isn't clogged(it's just a small radiator and could clog.Check unde the dash to see if the diverter cable is hooked up and moving the diverter flap.If all this is happening then you should have heat.Warm the truck up with the hoses on and grab the heater hose to see if it's warm.The only other thing I can think of to check is the box for obstruction(Mice and such like to nest in the boxes but it's doubtful they could blockk heat and not airflow.