7.3 idi thermostat replacement. Gaskets involved?
 

I want to check the thermostat. Is there a gasket involved with thermostats? Or do I just replace the part?

Yes, there's a gasket.

Mike

if its not overheating leave it alone.

I did this to my truck not that long ago; along with the oil cooler, and some other nick nack stuff.

To get access to it, I drained the radiator about half way into a bucket, then I took off the top rad. hose, removed the alternator, vacuum pump, and the fuel filter bracket.

The last part was necessary to get at the bottom bolt of the up pipe containing the thermostat.

There is a gasket, but I've red a lot of folks use the black rtv sealant instead of a gasket. The gasket at least when I bought the thermostat came with it.

I used some 600 grit sand paper to clean up the surface after, and after that I used some spray tack to hold the gasket in place. It worked out well, and haven't had a leak.

All in all, I decided with the amount of work, to flush the radiator, and block. For that, I used distilled water, with the motorcraft clean out stuff first(can't remember the name), after that, a couple more times with the distilled water,then filled with fleetgaurd.

I talked with a local diesel mechanic about the test strips for the SCA's, and he said they were about worthless after a couple months of hot weather; they don't use them, and instead base any antifreeze change with duration of time over anything else.