What does a temp gauge measure?

[backyardangler]

My temp gauge is innop. Just bought a new gauge and probe. Does the temp probe register the temp of the cylinder head or the temp of the water flowing through the cylinder head? Or both? Is a temperature gauge synonymous with a engine water temp gauge?

Thanks in advance for the clarification.

 

[pnwboat]

Re: What does a temp gauge measure?

There are several types of gauges.

The most common type measures the water temperature flowing through a water passage in the head. These have a threaded sending unit that is screwed into a hole in the water passage of the head. Since the water flows through the head, the head temperature is usually the same as the water.

There are some instances where you have an air cooled engine. Since there is no water, the temperature gauge on these motors have a sending unit that is mounted on the surface of the head. Usually held in place with a bolt or epoxied in place. Here you would be measuring the temperature of the surface of the head itself.

It has been my experience ( I'm not an expert in this area) that in most causes when someone is talking abut an engine temperature gauge, they are actually referring to an engine water temperature gauge. Air cooled engines are not as common as water cooled ones.

 

[backyardangler]

Re: What does a temp gauge measure?

Thanks for taking the time to explain that for me. Now I get it.

This forum has been much more help than my local outboard guy.