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© 1998 Brian F. Schreurs
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The car in question is our oft-visiting 1995 Mustang GT. The owner had a 180-degree themostat sitting around so we put the sucker in. A word of warning: You mustn't let your car run so cold that the computer gets stuck in warm-up mode! It'll hurt performance and fuel economy, plus probably cause you to flunk your emissions test, and possibly damage the engine over the long haul. 180 degrees is about as cold as you should go on a 5.0.

These are the supplies we used to siphon out the antifreeze.

This job really is too easy. If you can figure out which end of a wrench to use, you'll be okay.

The first thing you need to do is drain enough antifreeze so that it won't pour all over the engine when you undo the upper radiator hose. This should be really easy if you have some way to lift the car.

There's something that looks like a spigot on the passenger side of the radiator. By loosening the hex knob a little, you can let antifreeze pour out of the nipple underneath. Ours was hand-tight; we didn't even need a wrench.

The nipple is the perfect fit for a 3/8-inch inside diameter hose. We went to a hardware store and bought some clear vinyl hose (12 cents a foot) so that we could watch the fluid drain. Put the other end of the hose in a bucket or milk jug or something -- you don't want this stuff getting loose.

If you plan on reusing the antifreeze, the container doesn't matter much. Just be sure to rinse it out really well. If you're going to get rid of the antifreeze, please seal it and recycle it. This stuff is highly toxic! It will kill your dog, your cat, your kid, even you! Make sure you wash EVERYTHING that comes in contact with antifreeze; hose down any surface it spills on; keep it sealed up; don't touch your eyes while doing this job; BE CAREFUL.

This little elbow between the upper radiator hose and the engine contains the thermostat.

In our case, we weren't able to jack up the car. Here's how we drained it instead.

The skinny guy (who owns the car anyway) squeezed under there to work the valve. We ran the hose to a milk jug, then created a vacuum to suck out the antifreeze by holding a vacuum cleaner to the top of the milk jug. The suction is enough to draw out the antifreeze, but not so much that it'll get sucked into the machine. It's also enough suction to collapse the jug so we were only able to draw about a quart at a time. After each pull the milk jug was drained into another container. In this manner we emptied about a gallon and a half.

Remove the upper radiator hose from the thermostat housing. There is no need to disconnect it from the radiator itself; just undo the housing end.

If the weird Ford hose clamp has you worried, here's the trick: Take a Vise-Grip, clamp it onto the two tabs, then tighten the 'Grip's jaws with its adjuster until the clamp is completely opened. Then, just leave it that way until the hose is ready to go back on.

It is imperative that you completely clean the housing; it should be shiny metal by the time you're done.

Push the upper radiator hose out of the way.

The thermostat housing is held on by two bolts. They are both 1/2-inch heads. Note that one is longer than the other; remember which is which.

The bypass hose connecting the housing to the water pump can stay in place. Removing it might make the job a little easier, but the hose itself is a bear to get off so we recommend just leaving it.

Pull the housing away from the engine and, ta-daa, there's the thermostat!

Yank that sucker out of there. Ours needed a couple of friendly love-taps from Mr. Hammer.

The thermostat goes in first, then the gasket. Don't get it backwards!

Clean, clean, clean! You have to scrape the old gasket gunk away before continuting. Don't skip this step or you'll be doing this job twice. Scrapers will make this job easier, but a flathead screwdriver will do. After the main large pieces are gone, take one of those green brillo pads and really make it shine.

Place the new 'stat in the housing (with the core facing the engine) and place the new gasket on top of the 'stat. Then, just button everything back up!

Forgot which bolt is which, didn't you? Okay, the long one goes on the passenger side. See, aren't we nice guys?

Make sure you put the antifreeze back in.

So, in the grand scheme of things, what did this little operation do? Ummm... the car runs cooler! And the owner has the satisfaction of knowing that he has one more notch on his toolkit, one more weapon in the bench-racing war.