The Stovebolt Site Forums The Shop Area General Truck Talk Heater Stupidity

Our 1953 Chevy resto job is progressing well and the old boy "Baxter," runs like a champ. Yesterday, it was cold enough to pull out the heater knob. All fine for the first five minutes, then steam! Came out under the dash. I closed the heater control, and the steam was slowed and then only vented outside a small amount.
Any thoughts on what we may find when we take the heater cover off? I have never messed with one, so I am a probie when it comes to heaters (obviously)!

You probably blew a hole in the radiator in the heater or one of the connections. Are you running a pressure radiator cap? These old heaters were designed to run with a zero pressure radiator cap.

Heaters in those old trucks are pretty simple.. just a coil and an electric fan.

Hot engine coolant runs thru the coil all the time (unless you have a manual shutoff valve under the hood or a cable from the inside of the cab running to such a device) when you hit the switch, the electric fan forces air thru the coil and it heats it.

So if this "knob" you pulled is connected to a cable that goes to a supply cut off valve, then my guess is that your heater core has a leak. When you pushed the knob back in, you shut the supply off to the core.. which seems consistant with what you reported happening.

If the "knob" you pulled is actually the electric switch to the blower motor, then maybe it wasn't steam, but smoke?

From what you described, i'd guess either your heater core had a hole in it to start with, or opening the valve introduced some higher than 0 pressure that popped it.

My geuss is your heater controll valve is leaking.If you look under the dash and follow the rod the nob is conected to you will see the valve on the fire wall.You should see where anti frezze leaked down when the valve was open.If the heater core were leaking you should see anti frezze under the heater on the passengers side.Get a repacked valve from one of the venders and you should be good to go.Itryed several used ones and all leaked.Ron.

Thanks, everyone!
The "knob" was the heater control valve; I did know that. :-( Anyway, when I get back out there to it, I will check the leak.
There is a vendor...www.classicheaters.com - seems he can repair all types of cores. Might be of help to someone.

Any radiator shop can repair a heater core. It is just a smaller and simpler version of a radiator.

Ditto to what has been stated above.If you need a core I have the complete unit for a '53.Let me know.Also,it is a good idea to put a ball valve(shut off)on the heater input(just below the thermostat) so you can shut off all hot water going to the core in the summer.AD cabs are hot unless you are under way.Cowl vent open,both vent windows open and pedal to the metal!!!!

hope you got it fixed.

Funny you should mention it, I had my 72 core checked - complete dog. About 10 holes in it. I got the truck with it NOT connected which made me suspicious. The local radiator shop recored it for $55. Btw...your original post inspired me to haul it out. Especially when I have no engine and the seats are out. My ducting is an absolute mess too. Oh well. Call it 'job security'.