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How to Repair the Thermostat on Vehicles

by Contributing Writer; Updated June 12, 2017

The only way to repair the thermostat on a Vehicles is to replace it. The thermostat has no parts that can be fixed or replaced. Heating and cooling weakens the moving parts on the unit. Any attempt Vehicles repair is Vehicles futile and results in replacement in a short time. A thermostat is inexpensive to buy, but replacing it is complicated because there are several steps necessary to access the thermostat. When the car overheats quickly or does not warm up properly, the thermostat is the likely culprit.

Under The Hood:

 How to Repair the Thermostat on a 2001 Bravada

Raise and fully support the hood on the Bravada. Remove the radiator cap and place a coolant drain pan underneath the radiator.

Open the drain-cock on the radiator and completely drain all of the coolant from it. It should take 10 minutes to fully drain. After this time close the drain-cock securely.

Locate the thermostat housing on the side of the engine below the alternator. It’s not necessary to remove the hose from the thermostat housing. You can access the thermostat easily once the housing unbolted.

Slide your coolant drain pan directly beneath the thermostat housing. This way any coolant that comes out of the housing will go into the drain pan and not on the ground.

Remove the two bolts holding the heater core housing to the engine with a socket wrench. Pull the housing away from the engine and take out the thermostat.

Soak up any residual coolant from the thermostat’s mounting area on the engine with a shop rag. Then use another dry shop rag to go over the area once more including the flat mounting surface of the thermostat housing.

Install the new thermostat just as you removed the old thermostat. Your new thermostat should have a rubber seal already installed on it, if not you have the wrong replacement part.

Position the thermostat housing back into its original location and then return both of its bolts by hand to insure they thread correctly. Set your 1/4-inch drive torque wrench to 89 inch-lbs. and completely secure both bolts in place.

Refill the radiator with fresh coolant or with the coolant from the drain pan if it’s less than three years old. Return the radiator cap and then start the engine on the Bravada. Check for leaks every five minutes until the engine reaches normal operating condition. Take the truck for a test drive once you’ve determined there aren’t any leaks present.

Items you will need

  • Coolant drain pan

  • Socket wrench set

  • 2 shop rags

  • Thermostat

  • 1/4-inch drive torque wrench

 How to Repair the Thermostat in a 2000 Dodge Dakota

Locate the cover that holds the thermostat inside of the intake manifold on the Dakota. The cover can be found by tracing the radiator hose to the location on the engine where it connects to the intake manifold. The part that the hose connects to is called the "thermostat intake housing."

Remove the radiator hose from the thermostat intake housing by removing the band clamp that squeezes the hose around the housing. This is done with a screwdriver or an adjustable wrench. Once the hose is loosened pull it off of the housing and push it to the side.

Remove the thermostat intake housing from the intake manifold of the Dakota by removing the two bolts that hold it into place. With the bolts removed, the housing will lift off of the thermostat. Pull the thermostat out of the intake manifold.

Remove the thermostat gasket by peeling it off of the intake manifold. It's possible that the thermostat gasket will stick to the bottom of the housing. If so, pull it off of the housing. It is also possible that Dodge used PVC sealer to prevent fluid leaks. If they have done so, place a shop towel into the hole the thermostat was in and scrape the gasket and PVC gasket sealer off of the intake manifold with a scraper. Once the removed, pull the shop towel out of the hole.

Place a new thermostat into the intake manifold of the Dakota and then place a gasket onto the manifold. Reattach the thermostat housing using the bolts that were previously removed.

Reattach the radiator hose and tighten the band clamp around the hose and thermostat housing. The clamp should be tight to prevent any radiator fluid leaking. Start the Dodge Dakota and allow it to warm up. Inspect for any leaks. If there are any leaks the band clamp and thermostat housing should be tightened.

Items you will need

  • 2000 Dodge Dakota thermostat

  • 2000 Dodge Dakota thermostat gasket

  • Screwdriver

  • Wrench

  • Scraper

  • Shop towel

 How to Repair a Thermostat on a Nissan Xterra

Raise the hood and let the car cool. Open the radiator cap to release any leftover pressure. Place a large container under the radiator and open the drain on the bottom of the radiator with your fingers or a pair of pliers to drain the coolant. If you do not perform this orderly draining of the coolant, it will pour out all over the place when you open the thermostat housing. Doing it this way allows you to capture the coolant and reuse it at the end of the job.

Use a wrench and remove the bolts that hold the cooling fan in place and lift the fan up and out of the vehicle. You may need to remove a housing before you can access the fan depending on the year of the Xterra that you are working on. Place a wrench on the drive belt tensioner and rotate it counterclockwise to loosen the belt so it can be removed. Once the belt is out of the way, you should be able to reach the thermostat housing.

Loosen the clamp holding the lower radiator hose to the thermostat housing with a wrench and slip the clamp up the hose and out of the way. Pull the hose loose from the thermostat housing. With a wrench, remove the bolts that hold the housing in place and lift it off of the thermostat. Make a note of how the thermostat is positioned in its mount. The new thermostat will need to be placed in exactly the same way.

Pull the thermostat out of the mounting. Use a scraper and remove any old glue or gasket pieces from the mounting and housing. Apply a small amount of gasket sealer to the mounting and press the new gasket against the sealer to hold the gasket in place during the rest of the installation. Cover the gasket with a thin layer of gasket sealer.

Slide the new thermostat in place in the mounting. Replace the housing and install the bolts back into their respective holes by tightening them with the wrench. Slide the radiator hose back onto the housing. Push the clamp down on the hose until it is on the neck of the housing. Tighten the screw on the clamp until the hose is secure.

Place the wrench on the belt tensioner and rotate it counterclockwise so that the drive belt can be reinstalled. Put the cooling fan in position and insert and tighten the bolts. Replace the housing if it had to be removed. Make sure the drain valve on the radiator is shut.

Add the coolant back into the radiator and add any additional coolant that may be needed to fill the radiator. Replace the radiator cap onto the radiator. When about 45 minutes has passed since the thermostat housing was tightened down, start the car. Check for leaks before driving the car.

Items you will need

  • Wrench set

  • New thermostat

  • Thermostat gasket

  • Gasket sealer

  • Coolant

 How to Repair the Thermostat on a '99 Jetta

Unscrew the cap from the coolant overflow tank. Raise the front of the Jetta with a floor jack and slide jack stands under the vehicle’s subframe. Lower the Jetta onto the jack stands.

Crawl under the vehicle and find the under-engine splash guard. Remove the six bolts securing the splash guard using a ratchet and socket. Pull the splash guard rearward to disengage it from the front fascia, then pull it downward to remove it.

Find the radiator drain assembly next to the lower radiator hose. Position a drain pan under the drain assembly and turn the knob on the drain assembly counterclockwise to open it and start the flow of coolant from the radiator.

Close the valve once the flow of coolant from the drain assembly stops.

Move toward the passenger’s side of the engine and find where the radiator hose connects to the engine, just above the oil pan and behind the water pump. The component connecting the hose to the engine is the thermostat housing. Slide the drain pan under the thermostat housing.

Squeeze the ears of the radiator hose’s clamp with slip-joint pliers and slide the hose clamp about 5 inches away from the thermostat housing. Pull the radiator hose from the thermostat housing with a slight twisting motion.

Remove the two bolts securing the thermostat housing using a ratchet and socket, and pull the housing from the engine. Pull the thermostat from the engine. Using a small flat-head screwdriver, pry the O-ring from the thermostat housing.

Coat a new thermostat housing O-ring with fresh Volkswagen G12 coolant; you can identify this coolant by its pink color. Press the new O-ring into the groove in the thermostat housing from which you pulled the old O-ring.

Guide a new thermostat into the engine with the spring side of the thermostat going into the engine. Rotate the thermostat so the thin metal strip on the exposed side of the thermostat is in a vertical position.

Set the thermostat housing in place over the thermostat and hand-thread its retaining bolts. Tighten the thermostat housing bolts to 11 foot-pounds with a torque wrench and socket. Press the radiator hose back onto the thermostat housing and slide the hose clamp to about 1/2-inch from the end of the hose using slip-joint pliers.

Lift the under-engine splash guard upward and align its staggered tabs with the lip on the lower part of the front fascia. Press the splash guard forward until the lip is between the staggered tabs. Hand-thread the six splash guard-retaining bolts, then tighten them with a ratchet and socket.

Raise the Jetta off the jack stands using a floor jack, and remove the jack stands. Lower the Jetta to the ground.

Fill a clean, 1-gallon container about 4/5 of the way with clean water. Pour this water into a clean and sealable container with at least a 2-gallon capacity. Add just over a 1/2 gallon – 13/20 of a gallon, to be precise – of VW G12 coolant into the sealable container. Mix the container by sealing it and lightly shaking the container. This creates the 60-40 mixture of water-to-coolant the Jetta requires.

Pour the mixed coolant into the coolant overflow tank until the level remains steady in the middle of the two lines on the bottom half of the overflow tank.

Tighten the cap onto the coolant overflow tank, and turn the heater and air conditioner controls to the off position. Start the Jetta’s engine and hold the rpm at 2,000 for roughly three minutes. Allow the engine to idle until the cooling fan turns on, then turn off the engine.

Check the coolant level. If it is not at the upper line on the coolant overflow tank, slowly unscrew the overflow tank’s cap to allow pressure to escape, then remove the cap. Add VW G12 coolant until the level is at the top line, then close the overflow tank’s cap.

Items you will need

  • Floor jack

  • Jack stands

  • Ratchet

  • Socket set

  • Drain pan

  • Slip-joint pliers

  • Small flat-head screwdriver

  • New thermostat housing O-ring

  • Volkswagen G12 coolant

  • Torque wrench

  • Clean container, 1-gallon

  • Clean water

  • Clean and sealable container, minimum 2-gallon capacity

About the Author

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