How do you change the thermostat in a 94 ford explorer?

Answer 1

Unless you have recently had your cooling system flushed this is a good opportunity to flush the system, if your coolant is still fresh remove the upper radiator hose and let it drain into a large drain pan under the car. If it is not a nice bright green color then remove the lower radiator hose and let it drain out. Make sure you keep your pets inside as you're doing this because antifreeze has a very sweet smell and animals love to try to drink it but even small amounts will crystallize their kidneys and kill them.

To make this job as easy as possible you will need to remove a few things. Also, watch out for the sharp rear edge of the fan shroud. First, the air duct from the MAF sensor to the throttle body must come out (this is the large hose curving around the front of the engine going into the air filter box, if your filter has not been replaced in a while this is a good time to do a little maintenance).

Then get the accessory drive belt out of your way, this is very simple. Put a wrench on the spring-loaded tensioner and torque it to loosen the belt, then slip it off. The belt tensioner needs to be held in the tensioned position for access to the thermostat housing bolts, or it can be removed entirely. Removing the tensioner allows lots of room for you to put the thermostat housing back on.

Next, there's a small wire harness running right through the area where ideally you'd like to stick your fingers to work that third bolt once you've loosened it. You can loosen the plastic clip holding this harness to the alternator bracket and move it out of the way (from the original position on the left of the housing to the right).

The first 2 bolts aren't too tough to get to, but the 3rdcan be quite difficult. Use a 1/4 drive ratchet with an extension connected to a swivel connected to another extension connected to a 10mm socket for getting the 3rd bolt in and out has been known to work. Beware of dropping the 10mm socket in that "next to impossible hole to get the socket out of area". Perhaps you should keep a magnetic retriever handy just in case. Putting a piece of Duct Tape over the male ends of the connections between extensions, swivel, extension, and socket will keep them from coming apart, this trick is especially helpful during the reassembly phase.

The housing should now be loose and you can remove it. Not the orientation of the original thermostat, then install the new one with a new gasket. If you can't get it to stay then put a little Permatex Ultra Black on your finger and run it around the edge and this will make it stick.

If your belt is over 40k miles old then this is the perfect time to replace it. These cars use the new EPDM Belts which do not show signs of wear like old belts, you no longer look for cracking as a sign of needing replacement because these belts are much tougher than belts from "the good old days." Instead, the wear is measured by the gap between ribs, most auto parts stores have a little tool that slips in there to measure the distance between them and tell whether or not it needs replaced. At any rate, you should be able to get a new belt for $20 or less unless you opt for a "premium" belt. Keep the old one in a Ziplock bag with the spare tire in case of a roadside emergency (never know when you'll need one).

Once you have installed the new thermostatyou will need to burp the air out of the system. A simple procedure to do this is to add coolant and distilled water to the cold system until the fluid level is at the top of the radiator neck. Start the car and let it warm up. When the thermostat opens and water begins to circulate, the entrained air in the system should make its way to the filler neck. Keep adding coolant (50/50 mix of antifreeze and distilled water) to maintain the level at the top of the neck. After a while the coolant will warm up enough to start to expand, causing the coolant to start to rise in the neck on its own. When it does that, go ahead and put the cap back on, and top up the overflow bottle with coolant and distilled water to about two inches above the "cold fill" line. The system will continue to burp itself over the next hundred or so miles and it will keep itself full by using excess coolant from the overflow bottle. Check the bottle every 2-3 days and fill as needed until it no longer requires additional fluid to be added.