A healthy engine should run above 200 degrees. The radiator cooling fan on some vehicles doesn’t even engage until after the coolant reaches nearly 230 degrees. Although most modern engines are expected to run 200-230°F, most thermostats open at just under 200°F.
Disregarding a bad thermostat may result in catastrophic engine failure, so you must replace it as soon as it begins to show signs of trouble. Fortunately, you can determine when it’s time to get a replacement by watching for signs of a bad thermostat.
What Does a Thermostat Do?
Your car’s thermostat is a vital component that is actually pretty simple. It’s a valve located in your car’s cooling system. Its job is to regulate the amount of coolant that is recirculated back into the engine and how much is cooled via the radiator prior to being recirculated.
This ensures that the coolant in your engine stays within a specific temperature range regardless of the outside temperature. The valve is opened and closed with a spring, piston or another thermally controlled device.
Key Points:
- The thermostat is a valve that regulates coolant temperature, keeping it in the best range for the engine.
- If the engine runs too hot or cool, you might have a bad thermostat on your hands.
- You can check a thermostat for problems by examining the upper radiator hose’s temperature after the engine has warmed up.
- You should replace a bad thermostat immediately and avoid driving without one until you get a replacement part.
Problems A Thermostat Can Experience
The thermostat isn’t a maintenance or wear-related item that requires replacement at any pre-set level. Instead, it’s usually only replaced if failing, or whenever the water pump is replaced. The main problems a thermostat can experience are being stuck open, stuck closed, or leaking.
1. Thermostat Stuck Open
If the thermostat is stuck open, an optimal engine temperature is never going to be reached, and there will be no or little heat available in the passenger compartment, and engine wear can increase.
2. Thermostat Stuck Closed
If it’s stuck closed, the engine is going to overheat because coolant isn’t moving to the radiator. Debris or a broken spring in the thermostat could be responsible for it being stuck in either the open or closed position.
3. Leaking
Finally, the thermostat housing can fail and begin leaking coolant.
Signs Of A Bad Thermostat
The thermostat is responsible for regulating coolant flow through the engine. If the engine is cold, it stays closed to let it warm up.
As the engine heats up, the thermostat gradually opens, allowing coolant to reach the radiator. Whenever it begins to fail, the engine overheats and, if the problem is left unchecked, leads to your engine boiling over. This can lead to costly repairs.
While relatively cheap, a thermostat is one of the most crucial car parts. If you don’t want to change your engine entirely, you must address the root issue with your failing thermostat. You’ll need to look out for the following signs:
- Overheating (or overcooling)
- Coolant leaking
- Erratic temperature changes
- Strange sounds
- Heater problems
#1. Overheating And Overcooling.
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.
One of the lesser-known issues is the polar opposite of overheating. Overcooling happens when the engine does not reach the right temperature for its normal function. In this scenario, the thermostat is stuck open and overflows the radiator with coolant, drastically reducing the engine life cycle.
To prevent this, you should always watch your dashboard temperature gauge. If you don’t have one, monitor various warning lights in the instrument cluster. If you find yourself in a sticky road situation, try turning the heater on full blast to dissipate excess heat.
#2. Coolant Leaking.
A faulty thermostat most likely causes it to remain in its closed position. This means when the engine is running hot and the coolant normally flows toward it, the closed thermostat will block the coolant from going into the engine. This will cause the coolant to overflow from the thermostat housing.
If it stays like this and you don’t do anything to fix it, your coolant hoses will be the next things that leak. The quickest way to see if you’re leaking coolant is to just check under your vehicle. If you see green-ish or red-ish liquid leaking out of your vehicle and staining the surface underneath, then you definitely have a coolant leakage situation.
A stuck-closed thermostat prevents coolant from circulating through the engine, causing a buildup of pressure in the cooling system. As a result, coolant may leak from the thermostat housing, radiator, or hoses.
Coolant leaks can be identified by puddles of green, pink, or orange liquid under your vehicle. If you suspect a coolant leak, get it checked out asap, since low coolant levels can lead to engine overheating and costly damage.
#3. Strange Sounds and Temperature Changes.
Another symptom of a faulty thermostat is bizarre sounds. You may hear rumbling, boiling, or knocking coming from the radiator. All these signs point to an issue with your car’s cooling system.
The thermostat also affects the temperature of air that flows in your vehicle through the vents. If it suddenly changes from hot to cold or cold to hot, this is a clear sign of faultiness, especially if it happens erratically.
#4. Increased Fuel Consumption.
Both engine overheating and engine overcooling can largely increase exhaust emissions and damage fuel economy. This happens because the vehicle is not able to reach its operating temperature.
In this case, thermostat failure symptoms will most probably be translated into an increased fuel consumption and a resulting unexpected spike in monthly utility bills.
#5. Heater Problems.
A very difficult-to-spot issue can be explicitly discovered during the winter season. If the thermostat is stuck in an open position, no matter how high you turn up the heater, you won’t get hot air flowing through the vents.
This indicates a poorly functioning thermostat and should prompt you to change it as soon as possible.
#6. Sudden Air Temperature Changes Inside the Vehicle.
One of the more noticeable symptoms of a faulty thermostat is sudden changes in the air temperature inside your vehicle. If you experience a sudden drop in temperature followed by a rapid spike, it’s a strong indication that your thermostat is not regulating the coolant flow properly.
These temperature fluctuations can be uncomfortable for passengers and are often unrelated to your HVAC settings. If you notice inconsistent air temperatures that don’t match your climate control settings, get your thermostat checked out.
Related Posts: How To Replace A Bad Thermostat In Your Car?
Car Thermostat Replacement Costs
The thermostat car replacement cost can vary immensely. Some cars have complex engines, making it more difficult and time-consuming to access and replace the thermostat. Luxury or performance vehicles may have higher parts and labor costs.
The cost of a new thermostat can range from under $10 to $175 or even higher, depending on the brand and vehicle. Consider the cost of coolant too. As well, labor costs for professional installation typically add $100 to $300, depending on the complexity of the job.
Repair costs can vary by region, with urban areas typically charging higher labor rates than rural or suburban locations. And don’t forget to factor in that labor rates are higher in areas where cost of living is higher.
Plus, if your thermostat failure is accompanied by other cooling system issues such as a faulty radiator or water pump, the overall repair cost will increase drastically.
Generally, you can expect to spend between $50 and $200 for a DIY thermostat replacement.
How Often Should You Get Car Thermostat Replacement?
Car thermostats eventually fail because of normal tear and wear. However, they still function effectively for up to 10 years before needing a replacement.
Since a problem with a car’s thermostat can lead to expensive engine repairs, it is important to prolong the life of the thermostat. Here is how to do it.
- Monitor the coolant levels in your vehicle constantly.
- Always use the appropriate coolant for your vehicle. Avoid mixing to mitigate the corrosive effects of a mixture of different coolants.
- Avoid adding dirt and debris to the coolant reservoir.
- Ensure you have proper engine mounts in your engine bay to reduce vibrations that loosen parts of the car thermostat.
- Ensuring proper service techniques of the cooling system to avoid air getting in.
- Using a power clean flush once in a while to do a comprehensive clean of the cooling system to remove dirt and debris.
Can I drive with a thermostat problem?
If the thermostat is stuck closed, no, you should stop driving immediately; if you don’t, the engine can quickly overheat. An overheating engine should be shut off, and the vehicle should be towed. Overheating can severely damage the engine after only a few minutes.
If the thermostat is stuck open it may not cause engine failure, but you’ll likely notice poor performance, an ineffective heater and bad fuel economy. It should be replaced at your earliest convenience.
FAQs.
How does a car act when the thermostat is 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.
How can I tell if my thermostat is bad?
A bad thermostat can be detected when your AC or furnace is not turning on, your HVAC systems are not turning off, the thermostat not responding, your HVAC system is short-cycling, the room temperature not matching the temperature displayed on the thermostat, and the programmed setting resetting themselves.
How do I know if my car needs a new thermostat?
Signs My Car’s Thermostat Is Going Bad or Has Failed Completely:
1. Odd Temperature Gauge Readings.
2. Air Temperature Changes.
3. Coolant Leaks.
4. Strange Sounds.
5. Heater Problems.
How do I know if its the thermostat or water pump?
If your car is overheating, it could be a sign of a faulty thermostat. However, if you notice coolant leaking from the front of the engine or a whining noise coming from the front of the engine, it could indicate a problem with the water pump.
How much does it cost to fix a car thermostat?
Generally, repairing a thermostat costs around $200 to $500. This is the price range you’ll find for most vehicles, although some may be higher or lower depending on the circumstances. But if we’re talking complete replacement, expect the price to increase by $50.