How Do I Replace the Thermostat in Buick Cars

by Contributing Writer; Updated June 12, 2017

The thermostat in your Buick car regulates the flow of coolant throughout the radiator. When the thermostat is going bad you will notice the temperature gauge constantly rising in the hot position. Replacing the thermostat will ensure your Buick car does not overheat. The thermostat opens and allows the coolant to flow through the motor to allow the engine to cool down. Once the engine is cooled down, then the thermostat will close and repeat the cycle when the engine starts getting hot.

Under The Hood:

 How Do I Replace the Thermostat in a Buick 3800?

Locate the metal thermostat cover on top of the Buick's intake manifold by following the upper radiator hose from the radiator to the location where the hose clamps to the engine. The hose clamps to the thermostat cover.

Remove the radiator hose from the thermostat cover. If the clamp is original, use pliers to squeeze the compression tabs together then pull the hose off the cover. If the clamp is an aftermarket band clamp, loosen the clamp using a socket and ratchet. With the clamp loosened, pull the hose off the thermostat cover. Lift the hose vertically so any fluid in the hose flows into the radiator.

Remove the two bolts that hold the thermostat cover onto the intake. Inspect the bolts. If they have heavy corrosion or rounded heads, discard them.

Lift the thermostat cover off the intake. Sometimes the cover sticks to the intake. Push on the side of the thermostat cover to break it loose.

Scrape the old thermostat gasket off the intake manifold with a small scraper. Some of the thermostat gasket may stick to the bottom of the thermostat. Inspect it and remove any gasket stuck to the bottom with the scraper.

Pull the thermostat out of the intake manifold and place a new one into the manifold. The thermostat sits on a lip inside of the hole. The end of the thermostat with the large spring on it sits inside the hole.

Place a new thermostat gasket onto the intake manifold and secure the thermostat cover on top of it.

Slide the radiator hose onto the thermostat cover and secure it with the clamp.

Items you will need

  • Pliers

  • Socket set

  • Scraper

  • Thermostat

  • Thermostat gasket

 How to Replace the Thermostat in a 2000 Buick Century

Open the hood to access the engine compartment. Locate the top radiator hose.

Follow the radiator hose to the engine. Unclamp the hose by unscrewing the hose clamp with a flat head screwdriver. Pull the hose off the thermostat housing.

Unbolt the thermostat housing with a socket wrench. There will be two bolts to unscrew. Separate the thermostat assembly to expose the thermostat.

Pull the thermostat out with your fingers. Remember the position the thermostat was sitting in.

Place the new thermostat in the housing with your fingers. Ensure the thermostat is placed at the same position as the old thermostat was positioned.

Bolt the thermostat housing cover back over the assembly with a socket wrench. Ensure you tighten the bolts snug.

Clamp the radiator hose back on to the inlet pipe. Tighten the hose clamp with a flat head screwdriver.

Twist the radiator cap off to check the level of the radiator. You should be able to see coolant at the neck of the radiator. Fill with coolant if necessary.

Items you will need

  • Flat head screwdriver

  • Socket wrench

  • Socket set

  • New thermostat

  • Coolant

 How to Replace the Thermostat in a 1999 Buick Century

Raise the hood of the Century and position yourself on the driver's side, over the upper intake manifold area of the engine. The upper intake manifold is the large aluminum piece on the top of the engine; the air intake hose is connected to it. Locate the thermostat housing just in front of the intake entrance. A small black radiator hose leads to the thermostat housing and a hose clamp fastens the hose to the housing. Place a pair of needle nose vice grips or a radiator hose clamp onto the small radiator hose, as close to the thermostat housing as possible.

Place a drain pan directly beneath the portion of the engine you are working on. As you've clamped off the hose leading to the thermostat housing, you should experience very little loss of coolant. Coolant contains ethylene glycol, which is toxic to humans and animals; it has a sweet aroma and taste that attracts animals. Using a drain pan will ensure that you do not drip coolant on the ground.

Remove the thermostat housing cover bolts from the engine using a 3/8-inch drive ratchet and socket with a 6-inch extension. Turn the bolts counterclockwise until you can remove them from the engine by hand. Pull the thermostat housing cover off by hand. Set the cover and radiator hose to the side so you can access the thermostat.

Remove the thermostat in the center by gripping it with a pair of needle-nose pliers. Pull the thermostat straight up from the engine and discard it immediately into the drain pan.

Scrape any residual gasket material from the old thermostat off of the engine, using a razor blade or box cutter blade. Scrape away from the thermostat opening, so you don't drop gasket material into your cooling system. Visually inspect the thermostat housing cover as well to ensure that there is no sealant or gasket material on the mounting surface of the housing cover.

Install the new thermostat gasket to the bottom of the new thermostat. Install the new thermostat and gasket assembly into the thermostat mounting hole on the engine. Reinstall the thermostat housing cover by hand. Tighten the housing cover bolts to 80 inch-pounds of torque, using a 3/8-inch drive certified torque wrench and socket with a 6-inch extension.

Open the radiator cap and remove it from the radiator. Start the vehicle and place the heater control panel on full fan speed and the selector switch on defrost. This will heat the engine quicker and allow pressure to build up in the system. Place your drain pan directly under the radiator and the radiator fill hole, as fluid will come out during this procedure. Allow the car to run for approximately 15 to 20 minutes to force all of the air out of the cooling system. Shut the car off and add coolant to fill the radiator completely.

Items you will need

  • 3/8-inch drive ratchet and socket set with 6-inch extension

  • 3/8-inch drive certified torque wrench

  • New thermostat

  • New thermostat gasket

  • Razor blade or box cutter blade

  • Small radiator hose clamp or needle-nose vice grips

  • Needle-nose pliers

 How to Change a Thermostat in a Buick

Position a bucket or drain pan under the radiator drain located at the bottom of the radiator. Open the valve and drain the radiator down below the upper radiator hose fitting on the radiator then close the drain valve. You can open the fill cover on the radiator to verify the level.

Locate the thermostat housing on the top front of the engine. There will be two or three bolts retaining it.

Remove the hose clamp holding the upper radiator hose to the housing. Loosen the clamp with a screwdriver. Remove the clamp and the hose. Set the hose aside for now.

Remove the retaining bolts on the thermostat housing and carefully lift it off the engine. It may be stuck to the block, so slide a putty knife under the lip and carefully pry it off.

Lift the old thermostat out of the engine and discard it. Use the putty knife to scrape any old gasket material from the housing and the engine. Use care not to drop any debris into the opening where the thermostat sits.

Position the new thermostat in the hole on the engine making sure that it is sitting flush with the lip around the edge of the hole. If the thermostat is not down flush, tightening the housing could damage the thermostat, the housing, or cause a leak around the housing.

Lay the new gasket over the thermostat, making sure there is no debris or old gasket material under it. Install the housing over the thermostat and gasket and reinstall the retaining bolts. Snug the bolts down and then torque them to the specifications outlined by the manufacturer.

Reinstall the hose onto the housing, securing it with the hose clamp. Do not over tighten the clamp or the hose may be damaged.

Refill the radiator with coolant and check for leaks. If none are found, start the engine and allow the motor to warm up. Check the temperature and watch for leaks as the system builds pressure.

Test drive the car and verify that everything is working as it should.

Items you will need

  • Thermostat

  • Thermostat gasket

  • Socket set

  • Torque wrench

  • SAE or Metric wrenches

  • Putty knife

  • Screw drivers

  • Clean bucket or drain pan

 How Do I Change the Thermostat in a 2005 Buick LeSabre?

Open the hood of the 2005 Buick LeSabre. Trace the radiator hose to the point where it connects to the thermostat cover, on top of the intake manifold.

Press the tabs of the radiator hose clamp together, using pliers. Slide the hose clamp off the connection so that you can remove the hose from the thermostat. Pull the hose off of the thermostat.

Remove the thermostat cover bolts using a wrench. Remove the thermostat cover.

Clean the mounting surface of both the thermostat cover and the intake manifold with a flat object such as a spackle tool. Discard the remnants of the old gasket.

Extract the thermostat from within the intake manifold and discard it. Replace the old thermostat with a new thermostat designed to fit the 2005 Buick LeSabre.

Lay the new thermostat cover gasket on the mounting surface of the intake manifold. Place the thermostat cover over it and tighten the bolts to secure it in place.

Replace the radiator hose on the thermostat cover. Press the tabs of the hose clamp and slide the clamp back onto the connection.

Items you will need

  • Pliers

  • Wrench

  • Spackle tool

  • Thermostat

  • Thermostat gasket

 How to Change the Thermostat in a 2003 Pontiac Vibe

Thermostat Change

The Vibe's engine bay is pretty cramped, and I could tell looking in that Toyota engineering was about to strike again. In order to get to the thermostat, I had to remove the alternator first. I started by draining the radiator with the drain petcock on the bottom. Then I set about removing the plastic cover on the top of the valve cover to get a little more clearance over the belt. I reached down toward the back of the engine, and used a 19 mm socket and ratchet -- pulling the handle toward the radiator -- to relieve pressure on the belt. With the tension released and the belt off, I checked it for cracks, splits and frays, and then turned my attention to the alternator.

I disconnected the alternator wire clamp, then removed the terminal cap and nut, and then the wire. From there, it was a matter of removing the two alternator mounting bolts, and pulling it out to access the thermostat housing behind it. The thermostat housing came off after removing its two bolts, and the thermostat came out afterward. After pulling the O-ring out, I tossed it in the trash. I cleaned the block and housing mating surfaces, and installed a new thermostat with the little bleed valve pointing straight up. With a new O-ring installed, I pushed the housing back on and installed the bolts. This was the high-output engine, so the bolts took 7 foot-pounds of torque; if it had been the standard engine, it would have been 8 foot-pounds.

The alternator went back on the way it came off, taking 18 foot-pounds of torque on the upper bolt, and 40 foot-pounds on the lower. The little wire nut took 86 inch-pounds, which is just hand-tight if you don't have an inch-pound wrench. I reinstalled the belt, pulling the tensioner forward again to slip the belt over the pulleys. After double-checking that it was seated on the pulleys, I refilled the system, bled it to get rid of the air, and checked my belt for alignment and thermostat housing for leaks while it was running. After everything was checked and done, I reinstalled the plastic engine cover, bought a giant firebird "Flaming Chicken" decal and stuck it to the hood.

 How to Change the Thermostat on a Buick Regal GS

Open the radiator cap to release the pressurized fluid system in the Buick Regal GS. It's possible that the radiator will mist or push fluid out of the radiator filler hole when the cap is removed. For this reason, the engine should be cool when this step is performed.

Remove the radiator hose from the cover that holds the thermostat in place. The cover is located on the Buick's air-intake manifold. Loosen the clamp that holds the hose onto the cover with a Phillips screwdriver. Pull the clamp onto the hose and push the hose off to the side.

Remove the cover that holds the thermostat on by removing the two bolts that hold it to the air-intake manifold. Set the cover and the bolts off to the side. They will be reused during the installation process.

Discard the old thermostat gasket and place a new gasket into place. Pull out the old thermostat and replace it with a new one. The thermostat is not bolted into place and can be removed by pulling up on it. Discard the old thermostat.

Reattach the cover that holds the thermostat into place with the bolts. Do not over tighten the cover. It's possible to break the cover since it is made with soft "cast" metal.

Reattach the radiator hose and tighten into place with the camp. Refill any lost antifreeze and replace the radiator clamp.

Start the engine and check the radiator hose and the mating surfaces of the air-intake manifold and the thermostat cover for any leaks. If there is a leak where the hose clamps onto the cover, tighten the hose clamp. If there is a leak around the thermostat seal, the cover should be removed and a fresh gasket with PVC gasket sealer should be used.

Items you will need

  • Buick Regal GS thermostat

  • Buick Regal GS thermostat gasket

  • Radiator fluid

  • Screwdriver

  • Wrench

About the Author

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