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Thermostat Install


1. Thermostat-the factory one is a 192degree part, get a 180degree if possible. Don't beleive the wanna-be's that say to use a 160, that's TOO cold. The 180 will keep engine a little cooler for more power.

2. thermostat gasket

3. silicone sealant-blue Permatex or the equivalent.

4. coolant

5. 1/2" wrench

6. flat blade screwdriver or 5/16" nutdriver or socket & ratchet

7. rubber mallet (a regular hammer & a block of wood will suffice)

8. gasket scraper or razor blade-also, some scotch-brite will be useful for final clean-up.

9. pliers

10. drain pan

11. funnel


DO THIS ON A COLD ENGINE ONLY! Start by locating the radiator drain petcock. It is on the right (passenger) side of radiator, near the bottom. Look down from the upper hose inlet, you'll see a spout with two ears. Put the drain pan under here. With the pliers on either side of the ears, turn counter-clockwise (from pass. seat view) . The petcock will go into the radiator as it unscrews, it looks backwards. Sometimes these can be a bear to break loose; be careful, the ears bend & break easily. When the coolant begins draining, remove the radiator cap, this will drain it faster. You only need to drain coolant until it's below thermostat level (it's at the engine end of the upper hose). If you wish, you can reuse the coolant if your drain pan is clean-or, you can refill w/new. Also, you can drain the rad. completely, to get more new coolant into system.

Remove the upper hose from the thermostat housing with the 5/16" nutdriver/socket or screwdriver. This is the time to replace this hose, but the budget will dictate these things :) . Removing the hose entirely is optional, you can leave it connected to the radiator. There will be some coolant loss when the hose comes off the housing, no big thing. There is a small hose connecting the thermo. housing to the water pump...this is probably the worst part of the job. Remove this hose from the thermo. housing, sometimes it's easier to loosen clamp, & when the housing is off of intake, remove the housing from the hose. Ford left us NO room to work on this part...it's a royal pain.

Removing the housing from the intake is a cinch. Pull the 2 bolts on the housing with the 1/2" wrench. Notice that you have 2 different bolt lengths, they only go in the housing 1 way. Take your rubber mallet, & swinging from the intake to the radiator, give the housing a good rap. Substitute the rubber mallet w/ a hammer & a block of wood if necessary, be sure to hit the wood & not the housing. Expect more coolant loss when the housing comes free of the intake.

OK- the thermostat sits in the intake, & is held in place by the housing. Notice which end is facing the radiator & which end faces the intake. Match this up w/new thermo. to get an idea of how it's placed. Sometimes the thermo stays in the intake, sometimes it comes off with housing, just pull it off of either. If your thermo. is original, it'll have a FoMoCo part # & say "192" somewhere on it. 

Now you need to get the old gasket & any sealer off the housing & intake, use the scraper/razor blade, & finish up with the scotch brite. Clean mating surfaces are what will keep this from leaking, get them as clean as possible. Make sure there isn't any coolant dribbling out of intake & onto mating surface, try to keep it dry once it's clean.

Look at your new thermo.- it may have a "this side to radiator" stamp or something of the like. Make sure it's facing the right direction when you install it!

If you can, get a gasket that has adhesive on one side..like a sticker. We get ours from NAPA. Set the new thermo. in the housing, making sure it's facing the right way, & put the gasket on the housing. The gasket should hold the thermo in place, this is why the self-adhesive types are nice. If not, put a bead of silicone around thermo. hole & the hole for the water pump hose, & set gasket into place. press down on gasket to seal it to the housing & let it sit for a few minutes, so the silicone sets up a little (but don't let it dry completely). Put silicone on the gasket, put housing in place, & install bolts. You may find it easier to put the bolts into the housing before putting housing up to intake. Also, put the small hose onto the housing before putting housing into position.Tighten the small hose clamp, re-install upper hose onto housing. Make sure petcock is closed before refilling radiator! :)

With either your old coolant, if it looks good still, or new stuff, fill the radiator back up. (This is where the funnel comes in handy.)

You'll notice that once it reaches the top, the level will slowly fall as the radiator fills. What you want is for the level to be maybe 3 inches from the top. 

Ok, moment of truth time! Fire her up!

What you're looking for is for the thermostat to open...you'll know this when the upper radiator hose becomes hot to the touch & you'll see the coolant flowing faster in the radiator. When this happens, success! You've replaced your thermostat!


Make sure you have extra water/coolant on hand when you start the car. There is now air hiding in the system- once the thermostat opens, it'll make it's way to the cap..it'll "burp". The level will begin to rise & will overflow, let this happen. Once the air pocket is out & the level begins to drop, start pouring in the water or coolant...be ready, it'll take more than you expect it to . Stop when you're about 1" from the top. Add to your overflow if necessary, put the cap back on & look for leaks. Once you're certain you're leak-free, take it for a spin, watch your temp guage & run the heater. All done!

Stangnet Staff

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