rv furnace pilot light and thermocuople.

[48Rob]

Likely the thermocouple is bad.
Could be a bad gas valve too...
If you don't have a buddy to check the thermocouple, just replace it.
It won't cost much, and then you will know.
If the thermocouple checks out okay, or you install a new one and it still won't stay lit, then the gas valve is probably bad.

Rob

[Mojave Bob]

One of the most dependable mechanical devices on the planet is the simple appliance gas valve. They very seldom go bad. But, an old RV furnace that has sat for umpti-eight years could get sticky. My first guess, though, is spiders. For some reason, spiders seem to love the smell of propane residue, and they will build nests and lay egg sacks in the burner and orifice area. That blocks the flow of gas. Try removing the burner, and blowing out the cavities.

[48Rob]

Bob,

Good advice!

I've cleaned many spider nests out of main burner tubes.
Inexpensive fix for what appears to be a bad valve (poor main burner flame)

However, if the pilot can be lit by depressing the button, and it has a good flame that engulfs the top third of the thermocouple, then the flow of gas to the pilot is not restricted, ruling out a spider nest as the cause.

Rob

[48Rob]

No, you do not want to "blow" anything through or at the gas valve, you can easily damage it, and it won't help anyway.
You can clean and blow out the burner tube, and the pilot assembly, once they have been removed.

What color is the flame on the thermocouple, yellow or blue?

Do you have any pictures of the flame?

[48Rob]

How about yellow?

If it is totally blue, without yellow, and looks like a mini blowtorch engulfing the last third of the thermocouple, then that rules out a bad regulator, and a dirty or misaligned pilot flame on the thermocouple.
You mentioned;

"I just got back from ace got a new thermocouple and going to see if I can get it to stay in one position over the flame I have already disassembled the hole furnace and found the thermocouple was floating around in its socket on the side of the burner box. I am going to try to get it fixed in one position securely and get it adjusted right with the tip just in the flame

If all is installed correctly and looks as described above, without being there to see it, I'd have to guess the control valve is bad.
Is the thermocouple installed gently into the gas valve?
It should be tightened until just snug, then another 1/4 turn.
No kinks or damage to the new thermocouple?

Maybe the last owner knew it didn't work, and thus threw it out?
Any time you are dealing with an old furnace it is a real gamble. Besides thermocouples and gas valves, you have the heat exchanger to be concerned with, as well as motors and on the newer ones, control boards.

A couple days ago I looked at a hanging heater in a public laundromat. The heater looked brand new, very pretty...except for a small rusty spot in the top corner of the heat exchanger. A closer look showed a finger sized hole all the way through.
The heater has been in continuous use every winter for years, and for quite a few has been pumping CO into the room where the patrons patiently waited for their laundry to finish.

Point is, sometimes saving a couple dollars isn't worth the risk.
If you have the knowledge and skills and equipment/tools to test and verify something is safe, great! Recycling is good.
But if you don't, it is in some cases like pulling the trigger without knowing how to check first to see if the gun is loaded.

Rob

[doug hodder]

Not sure this applies here, but in the past I've had a spider get into a propane heater type stove that I had in my house. It died in the line. The pilot would run just fine, when the thermostat kicked on, the spider carcass would flip up and block off the fuel and the stove wouldn't run. That only took me about 2 hours to figure out. Still not sure how the bugger got in there...Doug

[warnmar10]

The thermocouple produces a millivolt current and clean contact surfaces are imperative. Presumably the new thermocouple has a clean contact surface and the threads can get a good connection when tightened to the valve body. Before throwing the valve away I'd try cleaning the thermocouple contact surface on the valve. Use a sharpened pencil eraser or something similar to gently clean off the contact surface. If it still doesn't work I'd go looking for a new valve.