How to Change the Thermostat on Jeep Cars

If the thermostat stops working in your Jeep car then it must be replaced. Taking a small job to a dealer to have repairs will be expensive even though the mechanical thermostat only costs a few dollars. With a few basic hand tools you can swap out that broken thermostat in your Jeep car in a short amount of time. Not only will this save you money but it will reduce the amount of down time you would have while waiting for a dealer to complete the repair.

Under The Hood:

• How to Change the Thermostat on a 4.0 Jeep Engine
• How to Change the Thermostat in a 1995 Jeep Grand Cherokee 5.2l
• How to Change a Thermostat for a 2001 Jeep Laredo
• How to Change the Thermostat in a Jeep Grand Cherokee

 How to Change the Thermostat on a 4.0 Jeep Engine

Remove the radiator cap from your Jeep's radiator. Be sure the engine is cool before you begin.

Position the drain pan under the radiator. You will find a drain petcock on the bottom passenger's side of the radiator. Open it and drain the radiator until the coolant level drops below the top radiator hose.

Locate the clamp on the upper radiator hose at the engine end, where it is attached to the thermostat housing. Loosen the clamp and remove the hose from the housing.

Locate and remove the two bolts on either side of the housing using a wrench or socket and ratchet. The housing may come off when the bolts are out but often you have to tap on it with a rubber mallet because the gasket will cause it to stick.

Remove the housing and thermostat from the cylinder head. Clean any remaining gasket material from the housing and cylinder head using a putty knife.

Install the new thermostat and gasket, making sure that the thermostat is oriented the same way the old one came out. If the thermostat is in backward, it will not function properly and the engine will overheat.

Tighten the bolts on the housing using a wrench or socket and ratchet. The bolts should be tight, do not to tighten them so hard that you break the ears off the housing.

Reinstall the upper radiator hose and tighten the clamp using a screwdriver. Replace the coolant in the radiator and install the cap. Test run the engine to verify it is working properly.

 How to Change the Thermostat in a 1995 Jeep Grand Cherokee 5.2l

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.

 How to Change a Thermostat for a 2001 Jeep Laredo

Locate the thermostat housing by following the radiator hose from the thermostat housing to the point where it connects to the Jeep's intake manifold. The metal part that the hose connects to is called the thermostat housing. Remove the bolt that secure the housing to the intake with an adjustable wrench and then pull up on the housing to expose the hole in the intake where the thermostat is secured.

Remove the thermostat from the intake manifold by lifting up on it. Due to age, the thermostat may be hard to remove. It is not bolted into place. The only way to remove it is to firmly pull up on it. Place the the new thermostat into the intake manifold with the end marked "top" facing out of the intake.

Remove the old gasket by scraping it off of the intake manifold with a razor blade. Do not get any of the old gasket into the hole that the thermostat was removed from.

Place a bead of RTV silicone gasket maker onto the gasket surface of the intake manifold and allow to to dry for 10 minutes before moving on.

Place the thermostat housing onto the intake manifold of the Laredo and bolt it back into place.

 How to Change the Thermostat in a Jeep Grand Cherokee

Open draincock on the radiator to drain the coolant from your Jeep Grand Cherokee. This draincock is located on the lower right side facing the rear of your Cherokee. Use a sealable container and reuse the coolant if it is relatively new and clean.

Follow the upper radiator hose to the point where it meets the thermostat housing. The thermosat is located inside the housing. Use a clamp tool or vise-grip pliers to loosen the clamp holding the hose to the housing. Work the end of the radiator hose free of the thermostat housing.

Remove two bolts holding on the thermostat housing cover. Pull off the cover. Take note of the position of the old thermostat. Remove and install the new thermostat in exactly the same position.

Scrape off residue of the old thermostat gasket from the inside of the thermostat housing cover using a razor blade. Avoid getting any debris inside the thermostat housing.

Install the new gasket. Reattach the thermostat housing cover and radiator hose. Start your Jeep Cherokee and run the heater on high. Allow the engine to warm up. Check for leaks.