The Stovebolt Site Forums The Shop Area General Truck Talk Installed a heater, not working well though.....

I put a heater in my 48 1/2 ton Chevy. Believe the heater is from a 51 Chevy. The fan works well, but the blowing air is not too warm. I put a thermostat in the truck and took the top hose of and filled the core with water. Does it matter which hose goes to the top and bottom plug on the water pump? Any suggestions?

No, but if you remove the top one, which I believe is the return from the heated core, with the engine running, you can pull it off, and make sure there is not an air lock in the heater. My trucks heater was luke warm until I back flushed it with the garden hose gently several times. I could not believe the crud that came out. Now, it works like a champ. After hooking it back up, I flushed the block, and rad, then filled with warm water and a cup and a half of calgon. Ran it for a half hour with no thermo, flushed it out, put in the green stuff.
Christopher.

Calgon!, take me away!

was the heater core used? if the tube diameter for the heater hose is 5/8 lets say, the total number of tubes in the heater that are not plugged that eaqualed the same amount of area of the inlet tube, both hoses would be hot to touch and still no heat from the heater, make sense?

Sounds like you have a blockage of some sort. It's easy to check. When the engine is warm grab both heater hoses. If both aren't hot you have a blockage issue.

Normally your heater core acts as a trap for all kinds of dirt and sludge.Disconnect your heater hoses and flush it out good with your garden hose.First one way,then the other.I have got many heaters to working good with this method.

If there is a water shut off valve at the pump,make sure it is open.

There is no shut off valve at the pump, there is hot water in the top hose, not the bottom. I ran water through the core in the deep sink, it looked clear. Maybe it is air bound?

Bring it down here (Texas) and you won't need - no stinkin' heater.

Hehehe

Here is a tip an old mechanic gave me. Remove the heater, fill with radiator flush/cleaner mixed to spec. Let it set. flush and back flush, repeat as needed. This will do two things give you a clean core, and show any leaks. This works only if your heater lines are clear. (don't ask how I know!!)I hope this helps, Jim.

So, I messed with the heater for a bit today. The top hose from the core is 3 inches below the top of the radiator inlet hose. I switched the hoses and still no luck. Could the water pump be bad? It does cool the motor though.....

Depending on which type heater you have, you may have a bad heater valve. I installed a refurbed valve when I installed my Deluxe fresh air heater and learned that when it is in the "off" position (cooler rather than warmer direction) the hoses will not fill with water/coolant and therefore the core will not fill and become hot.

Check out your heater valve or turn your valve to the open position.

Spot

What type of heater did you install ?

Air flow heater which installs against the passenger kick panel and pulls fresh air in the cab.

Recirculating heater: recirculates the air in the cab.

See the link for 1951 heater installation.

1951 heater installation

Thanks for the info bowtietim, The heater recircs the cab air. I have both hoses coming off of the water pump. Should one come off of the thermostat housing? Having trouble getting that plug loose. The pipes on the heater are on top of each other about 6 inches apart. Not sure from what year truck.....Might replace the water pump next?

Yes,as you can see in the installation manual page 40.
You might have to put a little heat on the plug.A hand held propane torch should heat it enough.

sounds like it might be air locked, run the truck to operating temp with the cap off, you should see the water circulate in the top tank and should feel hot to your finger, bring the rpm's up for a while and both hoses should hot to the touch, one a little cooler should indicate the heater is working...

"I have both hoses coming off of the water pump. Should one come off of the thermostat housing? "

Bingo. There's the problem. To have heat you need flow. With both hoses sucking you won't get any. Yes, you need one hooked to the thermostat housing to supply heated water.

Now I'm confused, where in the world did you find a water pump with two outlets??? There's one tapped hole in the stat housing and one tapped outlet hole in the pump housing just above the lower radiator hose. Did someone put a tee in the pump housing????
Why don't you put a pucture up and we could actually see what you're talking about. To late now, but a picture is worth a thousand words!
Denny Graham

I get the gut feeling that it's an misunderstanding of how the loop works & what is what on the front of the engine. I'd wager one is on the thermostat housing & a plugged core is the culprit.

I have a large-truck water pump that had more than one outlet on it (1960, 261 engine).

I'm bankin' with you Tiny. "Picture is worth a thousand words"
Denny G

The 261 pumps have two threaded outlets. The last replacement "235" pump I bought had two also. I assume all replacements are built to work on either.