I've noticed that some thermostats have a tiny hole with a dohicky that looks a bit like a check valve in it, like the one circled in this image:
But most of the thermostats that I deal with in industrial engines don't have those. Particularly GM industrial engines. Those same engines also almost never have an air bleed port, which makes burping them after draining and refiling the cooling system a pain.
Would it hurt anything to drill out a small hole, to make the T-stat more like the one in the picture? That way the air could more easily escape from the block when refiling the cooling system, and I could spend less time warming it up and burping it.
That's more or less standard practice for many, I've notched them with a hacksaw before. The old school trick is to just hold it open with an asprin or two when you install it, once it heats up and the thermostat opens farther, they fall out and dissolve.
Why not use automotive thermostats and skip the whole drilling portion?
Because the GM automotive thermostat doesn't have the hole either
A lot of aftermarket ones, even the nice ones, are missing the hole.
The hole is exactly that.. its for air bleeding... If you do drill a hole I would go a little smaller then that hole you see in the thermostat pictured...
I like the asprin trick... I'll have to remember that..
the only time a hole there makes any difference is when you are filling it up.. there are other ways to get the air out of the system, but usually it takes care of itself as long as the heater core is hooked up and it doesn't have some sort of a water shutoff for when the AC is on "cold".. if that's the case, just take the highest heater hose off and fill until coolant comes out..
If you look at the part where the two edges seal against each other, you will almost always find a small notch for bleeding.
Streetwiseguy wrote:
If you look at the part where the two edges seal against each other, you will almost always find a small notch for bleeding.
i've never seen a "notch" in any thermostat i've ever installed.. i play mostly with American V8 stuff, if that matters..
novaderrik wrote:
Streetwiseguy wrote:
If you look at the part where the two edges seal against each other, you will almost always find a small notch for bleeding.
i've never seen a "notch" in any thermostat i've ever installed.. i play mostly with American V8 stuff, if that matters..
Look closer from the underside
I just love that you can use aspirin to avoid the headache of trapped air
Some thermostats don't need them... like most GM engine designs. The chamfer in the intake where the stat sits is deep enough that the stat isn't pinched. It is allowed to float a couple millimeters.
Many import stats that don't use a gasket (instead using a rubber ring) do benefit from a bleed hole.
Bottom line is that thermostats don't seal tightly so its not usually an issue. Even if it were, the first time it opens, the air passes through anyway.
And I love the aspirin idea.
I've never seen one that doesn't have something, either a drilled hole, or this:
