She's getting up there in age, but my 1995 Grand Cherokee just keeps on going, and the 235-horsepower, 5.2-liter, V-8 engine is still plenty powerful for day-to-day use. As she gets older, little issues pop up here and there, and one example is when my SUV's thermostat stuck closed on the way home from work a few nights ago. Fortunately, this big V-8 is easy to work on, and I had the thermostat in and out in no time at all.
Removing and Installing New Thermostat
To drain my Grand Cherokee's radiator, I sat a drain pan under the radiator petcock -- on the lower passenger's side of the radiator -- and loosened the petcock with an open-end wrench. The thermostat housing is near the top, front of the engine, and I found it by tracing the upper radiator hose toward the engine -- the metal component connecting the hose to the engine is the thermostat housing.
When installing the new thermostat, I positioned the jiggle valve -- the valve on the outer edge of the thermostat that jiggle freely -- in the 12 o'clock position. I had to create my own thermostat gasket for my Cherokee, using liquid gasket maker on the mating surface on the engine and the thermostat housing. I did so by running a constant bead around where the thermostat sits in the ending and housing, and keeping the bead to the inside of the bolt holes. After installing the thermostat housing, I tightened the housing bolts to 200 inch-pounds, using an inch-pound torque wrench and socket.
I refilled the radiator to the base of its filler neck with 50-50 premixed, ethylene glycol-based coolant, then installed the radiator cap. I then filled the coolant reservoir to the "Full Cold" line. From there, I idled the engine with the heater set to "High," until the temperature gauge reached about halfway, then turned the engine off and let it sit until it was cool to the touch. I then refilled the coolant reservoir to the "Full Cold" mark. I had to repeat the idling, cooling and refilling procedure three times to bleed out all of the air.
Warnings and Tips
Take any old coolant to a used automotive fluid recycling center or an auto parts store for disposal.
Coolant is highly toxic, so keep animals and children away from your work area, and always store coolant in a safe manner.