How do I change the thermostat on a 1994 Jeep Wrangler 2.5L?

Answer 1

--Start by draining the rad fluid from the rad. Leave the plug out for the entire process

--Then start the car, and run it till it reaches normal operating temp. (around 190of).

--The thermostat should kick in and start cycling engine coolant into the rad, which in turn will drain out the bottom of the rad. (be sure not to overheat your engine in the process of draining the coolant from the engine core).

--Once the fluid is cycled out of the cooling system, shut off the car, and wait till the engine cools off (DO NOT touch the engine until it is cooled down!!)

--Once the engine is col enough to work on, start by removing the the thermostat housing. There should be 2 bolts, one on the top, and one on the bottom of the housing (you may need to use a short socket wrench to un-do the bottom bolt).

--Once the housing is off, remove the thermostat located directly inside the housing.

--Clean off the excess gasket gunk on the housing and housing cover with a wire brush (preferably a rotary wire wheel attached to a drill - the higher rev's will get the gunk off faster). Make sure all the gunk is off, or you won't have a perfect seal when you re-assemble! You can tell its all off when the surface is down to the bare shiny metal.

--Now you're ready to insert your new thermostat and gasket. Make sure you insert the thermostat right side up (usually located by an arrow pointing upwards)!! Failure to do so means failure of your thermostat and in turn failure of your engine.

--Place the gasket onto the housing, making sure that you have it on the right way (the housing is shaped a certain way, and the gasket will conform to that shape).

--Put the housing cover back on, and hold the cover and gasket in place while you re-insert the bolts and tighten (you may want someone to help you in this process).

--Tighten the bolts using goodentight's method (good and tight, but not overbearingly tight - you could risk stripping the bolts).

--Screw in your rad plug, remove the rad cap, and toss your engine coolant back in. Don't forget to fill your coolant reservoir to about 50% of full.

--Put the cap on your rad, and start your engine, wait for it to reach operating temperatures.

--you will see and hear your thermostat kicking in. Let it start cycling coolant into the engine, then shut off your engine one more time.

--Wait for the engine to cool down again, remove the rad cap, then give the coolant intake and outtake hoses a squeeze. you will hear some gurgling sounds. that is air in your hoses. By squeezing them, you are forcing the air out into the rad, and our the top plug. so squeeze them until that sound dissipates (It won't fully dissipate, and you may want to do it 2x, start your car, run it up again, so the thermostat kicks in, then shut it off, wait for it to cool, and squeeze some more.), then plug up the Rad again, and start up your engine. The bubbles will dissipate over time, but too much air in the hoses is not a good thing, thus the squeezing method works great.

--Lastly, check your engine coolant levels for the next couple of days, just to make sure they are optimal (you may have to add more,, it seems when you remove any fluid from a car, theres always a little spillage, or evaporation).

--Enjoy your nice cooler engine. :)