How to test a thermostat?

I was out running my x30 (used) for the first time this weekend. But I had trouble getting the water up in temperature. After round 3, the temp was still under 30c. Only when I was using duct tape, I manage to reach 45-48c after a couple of rounds. Any way I could test the iame thermostat ? Do they need some kind of descaling from time to time ?


Def sounds like it’s stuck open. I’m not sure how it works inside but if it’s not working it won’t do any harm to try some descaler or vinegar. Since it’s open just drop it into a cup of the stuff n see what happens.

If you can remove it, throw it in a pan of water on the stove and see what it does when it gets hot.

It’s a 50 deg thermostat, if the water temp running is only getting up to 30 then it’s open.

Take it off and blow through it :joy:

You can’t see inside the thing anyhow

You’d have to put a hose on each end, put it into water above 50 deg and see can you blow through it, then put it into cold water and see can you not


Thanks guys…

But in order to work, its always open a little bit right ?? So it knows the current temperature?? And goes full open, when water reach 50 deg ??

Yeah there has to be some sort of bypass inside to prevent pressure build up. Good point

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There is usually a smaller hole in the main diaphragm of the thermostat that allows a small amount of water through until the valve opens and more water can pass.

In the picture above, it looks like the housing is two piece and possibly can be unscrewed to remove the thermostat itself. Testing is pretty straight forward. Submerge the thermostat in a vessel of luke warm water with the thermometer in it. Add boiling water to the vessel until the thermostat opens and note the temperature.

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You are right.
So I took it apart… Lots of dirt and calcium, was building Up.
I could see it moving though, when I gave it hot water. But now I will put the parts in some vinegear over night. And then time will tell.

Make sure you are using distilled water only. I got a big shaking of the finger last time I did a top end. Was warned about tap water and calcium build up.

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Its a used motor. But yes I Will only using distilled water.

If you have scaling on the thermostat, you likely have scaling in the radiator too. I found mine was pretty bad. I ended up flushing it with CLR then Vinegar. Came out super clean.

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I gave my radiator this

How do you use it? Do you add it to the existing circuit of engine, radiator and water pump or do you use an external pump and circulate it through the radiator separately?

Take the radiator of. Put a hose between top and bottom, so you have a closed system. Put the degreaser in, and fill Up with water.