How to Change the Thermostat on a 1998 Monte Carlo 3.8

The thermostat ensures the heater works correctly.

The thermostat in a 1998 Chevrolet Monte Carlo regulates the flow of coolant in to the motor. When the motor starts getting hot, the thermostat automatically opens up and releases just enough coolant to cool the engine down. The coolant goes through a cycle through the motor. The coolant is sent through the motor to the water pump. The water pump pushes the coolant through the radiator. The radiator dissipates the heat of the coolant so the coolant can go through the motor to pull the heat out. The thermostat is the brain of this process.

Things You'll Need

• Socket set
• Socket wrench
• Thermostat
• Thermostat housing gasket

Instructions

Removing the Thermostat

1. Open the hood to access the engine compartment. Locate the top radiator hose. This hose will be installed to the radiator from the engine.

2. Trace the hose to the engine and locate the thermostat housing at the end of the hose. The thermostat housing will have two bolts on top to open the housing and exposing the thermostat.

3. Unscrew the two bolts with a socket wrench. Take the top of the housing off with your fingers.

4. Scrape the old gasket material off the housing surfaces with a putty knife or a razor blade. This will help to ensure the housing does not leak later on.

5. Pull the thermostat out of the housing with your fingers. Ensure you remember how the thermostat is positioned when you pull it out of the housing.

Installing the Thermostat

1. Place the new thermostat in to the housing with your fingers. It should be positioned the same as the defective one was previously.

2. Place the gasket around the surface of the housing. The holes on the gasket must match up to the holes on the housing.

3. Bolt the top portion in place with a socket wrench. Ensure both bolts are tight on the housing.

4. Open the radiator cap to inspect the coolant level. Some coolant may have been lost while changing out the thermostat.

5. Inspect the coolant level. The coolant should be visible when opening the cap. Top off with antifreeze.

6. Twist the cap back on to the radiator. Close the hood.

Tips & Warnings

• Specify the year, make and model of the car when purchasing the thermostat to ensure you receive the correct thermostat.

• Only work on coolant system when the vehicle is cool. Do not work on a hot motor as it will result in burns.

References

• Autozone Official Site-Thermostat Replacement
• "Chevrolet Lumina, Monte Carlo and Impala Haynes Repair Manual for 1995 thru 2005 Front-wheel Drive Models."; John Haynes 2005