How to remove thermostat on Atwood water heater

[73gitane]

My water heater heats water just fine but refuses to turn off the flame. If I let it go indefinitely the release valve activates and lets out a billow of steam and hot water.

I assume my thermostat "button" may need testing but it is interesting the other cut off button isn't activating. Anyway I thought I would take the button out for testing. How do you get that sucker out? The retaining washer for the thermostat has just one cutout in it while there are three tabs at the water heater. Even though I rotate the washer to clear one tab, the other two tabs keep the thermostat captive. I could bend them but there must be a better way and thought I better ask.

Thanks,
Steve

[73gitane]

Ok I thought it was a bit ridiculous I couldn't remove the tstat so I went back out and after some fiddling I was able to take it out. And the tstat tested fine when I heated it up away from the tank.. Nothing seemed very corroded but I'll clean contacts anyway. Maybe a chance the controller could be bad?

[NeilV]

The bayonet mount gets loose so that the stat is not making good enough contact with the tank to read the temperature correctly or the tank where the stat makes contact gets corroded which also prevents getting an accurate reading. Also the self adhesive insulated cover strip also can fall off which will also cause low readings and run on. Get it fixed before someone gets scalded or the sidewalls of your coach get deformed from the steam that is released when the ptr valve blows.

[73gitane]

I put both buttons in water and measured resistance when brought to a boil. The t-stat opened up at 167 and the other never opened up at max temp of 209. It did open up once a heat gun was applied. Guess I'll order a set to replace them with. Does anyone bother putting thermal grease on these things to avoid bad contact?