Home › Forum › Ask A Member › Are Sierra thermostats OK? › Re: Are Sierra thermostats OK?
Nuts! Y’all (I’m Southern) aren’t listening to my question. I fully understand how the system works and even tore down a powerhead to illustrate how it works. Furthermore, I am not disputing the need for a thermostat.
The Original Poster questioned the absence of a bleed hole in a new thermostat he bought. Others later assured him that the bleed hole is not necessary. I maintain that it is necessary, thus my question.
I say that the bleed hole is necessary to allow a bit of water to flow past the thermostat heat-sensing pellet (and to purge the air from the water jacket surrounding the cylinders).
Examining the cylinder head that I just tore down, there is no outlet from the thermostat cavity except for the bleed hole in the thermostat poppet. If there is no outlet, water can’t flow into it. And if water can’t flow into it, the thermostat can’t sample it.
Unfortunately, I don’t have a thermostat, but it is kind of obvious that if I did have one, it and it’s rubber seal would sit on the flat surface surrounding the thermostat cavity and be pressed down tightly by the cap. Therefor the only way through the area would be the bleed hole in the poppet.
The public is watching this, and we shouldn’t even be arguing about it here. I’m signing off.