Why would the temp gauge stop working when the t-stat is removed? T-stats aren't wired in. Afaik there is no sensor in a t-stat. anythoughts? Could removing your t-stat cause a head gasket failure?

 

No, but removing the t-stat will cause it to run much cooler, thus the gauge not moving. Just an idea.

 

Running cooler will also cause no heat from the heater, a clogged cat from the truck running richer trying to get the engine to heat up, and increase in fuel consumption.

 

You know it's not good on a motor when you run it without a t-stat right? I am not gonna say why, because that has been a big debate on here before.

 

Why did you take it out in the first place? Maybe its possible the sensor isnt plugged in? Or the wire on the top is cracked/damaged?

 

You're right, removing the thermostat would not affect the gauge, other than for the obvious reasons pointed out. You could have knocked off the wire when pulling the T-stat.

 

Running with no t-stat in the summer really isn't an issue because your engine warms up much quicker in warmer weather.
In the winter, it takes much longer to get warm (if at all) without a T-stat. Very annoying seeing as you don't get any heat out of the cabin climate control.
I found out that my t-stat had sucked it's o-ring through itself cause my engine to be basically wide out t-stat all the time. I had to put a piece of cardboard in front of my rad so I could get some heat in my cab. Your engine will not warm up in cold weather without a t-stat or cardboard in front of the rad.
If you ever use/want heat in your cab, install a t-stat. They are cheap and easy to install. Two bolts and a little coolant and you're set to go.