Non-standard pilot thermocouple threads?

[Innovate1]

Have replaced a few thermocouples over the years and always thought the thread was the same and just the tube length and size/shape of the tip varied. Have a Suburban RV oven that is giving me trouble. Pilot won't stay lit. I checked the connections were secure and the output measured good but a thermocouple is usually a cheap/easy switch so got one at the local Ace store. It won't screw into the gas valve. Measured the outside of the thread as 0.310" on the original and 0.330" on the new one. And the thread pitch is finer. The hot end is different but fits in the holder so the only real problem is the valve end. What gives? Is this some metric size? How do I get a replacement other than from the stove manufacturer? I figured I could just pick up one locally. If needed I could go to a local distributor like Johnstone - my work has an account.

 

[BrandonV]

Imported? Probably a M8.

 

[Innovate1]

I hadn't paid any real attention to the threads before - just a quick look and they looked about the same. Now that I look closer at the different thermocouples at Ace site I see the thread pitch is noticeably different.

The 39" one is noted as for Procom heaters. Never heard of them before but the thread looks more coarse and the tip looks to be more the same shape as my old one.
https://www.acehardware.com/departm...ts-and-heating-supplies/thermocouples/4000496

Here's the 36" I got since the length matched.
https://www.acehardware.com/departm...ts-and-heating-supplies/thermocouples/4895082

The Eastman ones have fine threads. Here's a 24" one.
https://www.acehardware.com/departm...ts-and-heating-supplies/thermocouples/4894275

Looking at a few others there it looks like the 39" one is the only one with coarse threads. Think I will give that one a try. I tried a few google searches for more on different threads for thermocouples but didn't find anything.

 

[fitter30]

Suburban RV oven thermocouple puts out 14 mv. Standard furnace/ water heater 35 mv. Meter and a extra hand one to hold the pilot down two to measure voltage.

 

[The Cobbler]

there was a thread on here 6ish months ago with non standard thread size . I don't recall the outcome.

 

[The Cobbler]

 

[rlitman]

In theory, anyone can do that with their old thermocouple and a hacksaw.

 

[The Cobbler]

Yup. good old GJ ingenuity at work again

In theory, anyone can do that with their old thermocouple and a hacksaw.

 

[Innovate1]

Suburban RV oven thermocouple puts out 14 mv. Standard furnace/ water heater 35 mv. Meter and a extra hand one to hold the pilot down two to measure voltage.

This one is standard 30-35 mV output. Ended up finding the proper replacement on Amazon. It seems the valve was bad too. Wouldn't work with new thermocouple or new valve but works with both replaced.