How To Replace A Bad Thermostat In Your Car?

If your vehicle has been overheating or doesn’t warm up properly, you may need to replace your thermostat. If the thermostat sticks in the open position, it doesn’t keep the liquid in the engine long enough, so you have trouble getting your car warmed up. If the thermostat sticks in the closed position, the liquid isn’t allowed to get to the radiator, and overheating results.

Because replacing the thermostat is quite simple and thermostats are quite inexpensive, you may want to try this task before you take more drastic measures. Just be sure that you do this when your engine is completely cooled.

What is a Car Thermostat?

The thermostat is one of the important parts of the car cooling system, The thermostat is located inside the water line that goes from the engine to the radiator.

The main function of a thermostat is to maintain a minimum operating temperature in the car’s engine. When the engine is started, the antifreeze and coolant mixture is kept within the engine by the thermostat. It opens upon reaching a specified temperature. Coolant will then flow through the radiator to keep the engine at a temperature close to the rated temperature of the thermostat.

The ideal temperature conditions for the engine are in the range of 80-92 degrees Celsius, because at this temperature the combustion process in the engine will be optimal, and engine power works at its best and fuel consumption is efficient.

How does a car thermostat work?

Coolant will flow through the engine, and then it picks up the excess heat. It then leaves the engine and goes to the radiator. Here the excess heat is removed. It will then go through the cooling system and end back in the engine.

The thermostat is a valve that is situated between the engine and the radiator. When the coolant is too warm, the valve opens and lets the hot coolant through to the radiator where it is cooled down. If the coolant is not hot, the valve will stay closed and the coolant will continue to circulate in the block.

The thermostat has a wax-filled cylinder on its side. As the engine temperature rises, the wax expands and steadily pushes on a rod that opens the thermostat, allowing coolant to flow. When the engine temperature drops, the wax begins to harden, and the thermostat starts to close.

This process is continuous, with the thermostat adjusting how far it’s open or closed while the engine is running. Cars that run on hot coolant will never cool down and that will make your car overheat.

When to replace your thermostat?

“You may find that the heater in the cabin doesn’t blow out hot air and fuel consumption will increase.”

Symptoms of a thermostat stuck in the open position include the engine running cold, or at least not getting up to temperature. You may find that the heater in the cabin doesn’t blow out hot air and fuel consumption rises.

If the thermostat is stuck closed it will prevent water in the engine jacket from reaching the radiator. The engine will overheat (often quite quickly) and start running poorly. There’s a danger that the head gasket will fail, along with other seals – stop the engine immediately and replace the thermostat as soon as the engine is cool.

If your vehicle has ever overheated, you will likely need to get a new thermostat. Overheating can cause serious damage to the valve as well as the thermostat housing and the hoses and gaskets that are a part of your car’s cooling system. Excessive heat can cause things like hoses, gaskets, and even metal thermostat housings to warp and lose their original shape. When this happens, these vital components are no longer able to do their job as they should.

How To Change a Thermostat In a Car?

How to Replacing a Car Thermostat

Only basic tools are required for this job, although you may need to raise the car to remove the undershield.

  • Floor jack (if necessary). Not your car’s emergency jack
  • Axle stands.
  • Ratchet and socket set
  • Flat-bladed/Phillips/torx screwdriver
  • Rags Plastic scraper
  • Coolant – If it’s in good condition you may be able to reuse it.
  • New thermostat – You may also need to replace the housing.

#1. Drain Portion of Coolant.

Make sure the engine is cold and raise the vehicle on jackstands. Place a bucket under where you’re going to be working. Drain at least 50% of the coolant to avoid spills.

#2. Remove Thermostat.

Most thermostats are located where the top radiator hose joins the engine. Unbolt the thermostat housing from the engine block. Be very careful not to damage the housing as it is generally made from aluminum or a similar fragile material.

#3. Install the new thermostat.

Check the new thermostat to ensure that the part number is the same as the one you have removed.

Compare the new thermostat and its gasket with the old ones. If the new thermostat and the gasket that’s included with it aren’t exactly like the old ones, go back to the store for the right ones.

Inspect the mounting surface on both the thermostat and engine block. Remove any material with a sharp blade to ensure a good seal.

Fit the new thermostat, ensuring the air bleed hole is in the correct position. Check the thermostat is fully seated in its groove.

Carefully refit the thermostat housing to the engine block and bolt it into place.

#4. Refill the cooling system.

Refill the system with coolant. Run the engine to circulate the coolant and remove any air trapped in the system. Check that the temperature indicator gauge shows the coolant temperature is in the normal operational range. Top up the radiator or reservoir with coolant if necessary.

Car Thermostat Replacement Cost

The average cost for car thermostat replacement is $661 to $747. Labor costs are estimated between $127 and $161 while parts are priced between $377 and $381.

This range does not include taxes and fees and does not factor in your unique location. Related repairs may also be needed. Well, it depends on several factors:

  • Location of the mechanic shop. If you live in a large metropolitan area, expect to pay more than in a small town due to salary differences and mechanic qualifications.
  • Type of car. If it’s an older model, it’ll take longer for the mechanic to diagnose the problem, which could boost the overall costs. On the other hand, new automobiles are easier to handle because all the parts are readily available.
  • Type of thermostat being repaired or replaced. The type of thermostat being repaired or replaced will also affect the cost. For example, a mechanical thermostat generally costs less than an electronic one because it doesn’t require additional parts.

How Long Should a Car Thermostat Last?

A car thermostat is designed to last a long time – typically around 100,000 miles or 10 years. However, various factors can impact its lifespan.

First, driving conditions play a role. If you regularly drive in hot weather or stop-and-go traffic, your thermostat may suffer additional stress. You may need to replace it sooner. The type of thermostat and how well it’s maintained also affect its lifespan.

Note that regular maintenance is key to extending the life of your thermostat. If you notice any of the warning signs listed above, it’s best to have a professional check it out right away.


What happens when a car’s thermostat goes bad?

Overheating is the most common symptom of a failing thermostat. Due to corrosion or aging, your car’s thermostat can get stuck in a closed position. If this happens, the thermostat will not let the coolant reach the radiator, and, as mentioned above, the engine will overheat, causing severe damage.

Can a car run without a thermostat?

The thermostat sets proper operating temperature of the engine. It needs to be at that specified temperature to operate properly. In an emergency, the engine will run without the the thermostat but not at it’s best performance. without the thermostat, it will run cooler than it was designed to run.

Can you replace a car thermostat yourself?

Luckily, it only takes a few minutes and a couple of tools to change your thermostat yourself. Our guide will show you how to remove the bad thermostat and replace it with a new one!

How much does it cost to replace a car thermostat?

Car thermostat replacement time is 30 to 60 minutes, depending on the make of the car. It will cost you around $190 to $350, including labor. Thermostat repairs usually take more time, requiring extra time to diagnose and analyze the vehicle’s thermostat. It can take up to 2 hours.

How long does it take to change a thermostat on a car?

An average thermostat replacement takes around 1 hour, with some taking as little as 30 minutes. More problematic replacements can take a little longer where there are issues accessing an awkwardly positioned part or if it’s become seriously stuck in place.