+1 agreed.ps0303 said:Gunked up looking. Maybe rusted pretty bad. One way to test is after you remove the regulator, screw the cap back on and then turn the heater on. Hold the thermal regulator at the end of the opposite end with a pair a pliers and hold it over the hot exhaust coming out. You should see the regulator open as it heats up. If in a few minutes it doesn't open, it's bad. Shut down heater.
Now a word of warning, while removing the regulator, if it doesn't slide out easily, seems like it hung up on something, then the bypass is broken and hanging down in the way. They you will need to replace that and possibly the regulator.