The car thermostat regulates the flow of coolant in your engine, essentially functioning to cool the engine as it gets too hot.
Modern thermostats use a valve inlet inside the main hose leading into the radiator, which opens and closes based on temperature. In most cases, the ideal temperature range is between 195 and 220 degrees.
So, the radiator expands and opens the valve at around 220 degrees and closes again as the temperature nears 195. If this device starts to malfunction, you could have issues where the car stays too cold or where it overheats.
The average cost of thermostat replacement is about $200. That includes the new part, which ranges from $12-$150. The rest is labor, which is usually about 1-2 hours of work for your mechanic. You can expect this rate to double for a high-end car.
The table below shows a quick price comparison of car thermostat replacement cost estimates from reputable suppliers:
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How Much Does Thermostat Replacement Cost?*
The cost of replacing your car thermostat is mostly labor. Here, you can expect to pay an average of about $50 for a new thermostat. However, you’ll pay about $200 for the full job.
In addition, part of that cost is actually flushing and refilling your radiator. A radiator flush usually requires at least $6-12 in new fluid.
In addition, the make and model of your vehicle affects the cost of the installation and the part. And, if you have a vehicle that’s older than 15-20 years, it might have a cheaper thermostat without a valve inlet.
|Vehicle||Thermostat Cost||Labor Cost|
|Lexus Rx 350||$72-$186||$133-$385|
*Note: Prices are estimates and were correct at the time of writing (February 2022). Cost estimates may have changed since, our figures should be used as a starting point for your own research.
Thermostat Replacement Price Factors
In most cases, the largest cost factors in replacing a thermostat are labor. This means that costs vary depending on where you take your car.
In addition, you can pay different rates for the thermostat for your car. For example, if a popular brand has a made to fit or aftermarket brand for it, you could get your thermostat for under $10.
Additionally, the make and model of your vehicle, the cost of coolant, and some other factors will affect the cost of the work.
Cost of Labor
The cost of labor is always the most influential cost of replacing a thermostat in your car. In most cases, you can expect this to be about $100-$150.
For some luxury cars, that will go up to about $300. That’s especially true if you’re having the work done at a dealership.
Here, labor costs usually break down to about an hour of work. That means you’re paying your mechanic’s hourly rate plus the shop fee (usually 20%). Because mechanic’s rates average about $60 an hour, you can expect at least that.
If you aren’t sure what your mechanic charges, you can always call and ask.
Make and Model
The make and model of the vehicle affects several aspects of replacing the thermostat. For example, it directly impacts the cost of parts.
If your manufacturer charges more for parts, you’ll pay a premium for them. For example, Ford and Lexus charge more for OEM parts than Toyota and Honda do.
However, you can always get around this cost by choosing an aftermarket or made-to-fit part where one is available. That can greatly reduce the cost of some parts. However, not all mechanics will use them.
In addition, the make and model affects the complexity of taking the radiator hose and the thermostat out.
In most vehicles, this is relatively straightforward, and in others, your mechanic might have to remove quite a few parts of the coolant system to access the thermostat.
Finally, your mechanic will be more or less familiar with different vehicles. If you drive a common car, you can normally expect a lower rate.
That’s both because the service station might already have the parts in stock and because the mechanic is more familiar with the car and has a better idea of exactly how much work it will take.
Cost of Coolant
Replacing a thermostat always means draining the coolant.
You’ll have to pay for a flush and for new coolant. That normally won’t cost more than $20.
However, it will affect the costs and it is part of the total charge.
Many people choose to use remanufactured parts instead of new ones. While some mechanics will not use these, it can greatly reduce the cost of your replacement thermostat.
For example, most of the thermostat options under $10 in the chart above are remanufactured. Why are they so cheap?
It usually costs about 10% of the resources to remanufacture a part to manufacturer specifications for new parts as it does to make a new part. So, it’s a lot less resource intensive and it’s a lot better for the environment as well.
On the other hand, your part has been used before and there might be hidden stress points that cause an earlier failure than a new part.
However, most remanufactured parts are guaranteed and do come with a warranty, so you can choose accordingly. Not all mechanics will use them, though.
5 Signs of a Bad Thermostat
If your thermostat is going bad, you’ll likely notice. However, it might not be as fast as you’d like.
For example, you’ll eventually get to the point where your engine starts overheating. But, at that point, your thermostat is on the verge of complete failure or has completely failed.
There are other signs you can look for, but normally they require paying attention to gauges that you’d not usually have a reason to actually pay attention to. So, small signs can slip by unnoticed.
1. Temperature Fluctuations
If the temperature gauge is fluctuating up and down, it might mean that your thermostat isn’t timing properly with the engine. This can cause inconsistent temperature readings.
On the other hand, it might also mean the thermostat valve isn’t responding correctly, which intermittently sends coolant at the wrong points.
Because a properly functioning thermostat flushes the system with coolant when temperatures rise and stays closed when the engine is within temperature range, timing is essential.
When that timing goes off, coolant is no longer properly regulated and the temperature will spike up and down or won’t remain steady.
2. Heater Problems
Another common sign of a thermostat failure is if your heater stops working. Here, you might have issues with the heater fluctuating up and down, with it only being cold, or with it being too warm.
In either case, the thermostat isn’t properly regulating coolant – which is what’s used to heat the cabin of the car.
3. Steam and Leakages
If your thermostat isn’t properly cooling your vehicle, it can cause things to overheat.
Some coolant will start to steam, which results in pressure. Then, you might get leakages or steam jets from the valves and seals.
This is always a sign that something is wrong with the coolant system, even if it’s not the thermostat.
4. Rising Coolant Levels
If your engine is hot and the coolant levels are rising, you probably have a thermostat issue. That’s also true if the engine is hot and the radiator or expansion tank is full.
Why? The thermostat should be letting coolant out of the expansion tank when the vehicle is warm. If you’re fairly certain that the expansion tank is full, you can also test the temperature of the large hose under the radiator.
However, be careful, as aluminum parts can reach temperatures of 220 degrees if the engine is hot. If the thermostat isn’t letting coolant through, this hose will be cold.
If your engine is overheating, you have a coolant issue. While it might not be the thermostat, it might be.
You should also check for leaks, check coolant levels, and ensure your water pump is working, lines aren’t clogged, etc.
Unfortunately, there’s no real way to pinpoint the specific issue here without a diagnosis or testing the thermostat.
How Are Thermostats Replaced? (Step-by-Step)
Replacing the thermostat in your car is a relatively simple job and you can normally do it at home, in about an hour or less. Here, you might want to test to be certain the thermostat is bad before you do so.
However, most vehicle diagnostics cost more than the part itself, so you might not want to go in for a diagnostic.
On the other hand, if other parts of your vehicle are having problems and not (just) the thermostat, replacing it could be a waste of time and money.
Things You’ll Need:
- Wrench set
- Ratchet and socket set
- Disposable gloves
- Drainage pan
- Flat screwdriver
- New coolant (5 liters)
- Replacement thermostat
- Park the car on a flat and level surface. Turn off the vehicle and take the key out of the ignition. You may want to block the wheels and disconnect the battery from the negative post.
- Use a drainage pan and empty the radiator of coolant. You can do this using the drainage wingnut on the bottom of the radiator. Be sure to exercise safety precautions and you may want to consider using a tarp or a plastic bag to prevent any splash.
- Once the radiator is finished dripping, disconnect the large radiator hose from the bottom of the radiator. You can do this by pulling the clamp out of the radiator. Allow that to drain into the pan.
- Take the radiator hose off from the bolted connection. You’ll normally need a 12mm wrench for this.
- Move the assembly out of the way and remove the thermostat.
- Put the new thermostat in, with the wide end towards the hose. If you have an air toggle, make sure it is facing the top of the engine.
- Put the radiator hose back. You may want to check that the gasket is in good condition when you do so. Replace the bolts and put the radiator hose back into the radiator.
- Then, refill the radiator, either using the old coolant and a funnel or new coolant.
- Turn the engine on and allow it to idle. Then top up the coolant.
If you’re disposing of old coolant, put it into the containers the new coolant came in. Then, dispose of it at a local service station.
Keep in mind that coolant is extremely toxic to animals and people and should be handled with care.
You might still have questions about replacing your thermostat, if so, these answers might help.
Can you drive a car with a bad thermostat?
Usually, it’s a bad idea to drive a car with a thermostat.
Here, you risk overheating your car, causing damage to the radiator, and even blowing gaskets. That can cost you significantly more than simply replacing the thermostat.
In addition, if your car overheats while driving, you’ll have to park, wait for it to cool down, and hope you have extra coolant in the vehicle.
How long does it take to replace a thermostat?
In most cases, you can replace a thermostat in about an hour or less.
Timelines usually depend on familiarity with the vehicle, whether gaskets have to be replaced, and how complicated the coolant system in your car is.
What to do after replacing a thermostat?
If you’re still having issues after you replace a thermostat, you’ll want to have the pump, the coolant lines, and the gaskets checked.
You might also have issues with the radiator itself. For this reason, it’s usually a good idea to get a diagnostic before changing the thermostat.
The average car thermostat replacement costs $200. That normally works out to $10-$80 in parts and $60-$210 in labor.
However, you could pay more or less depending on the part, your mechanic’s rates, and the complexity of your vehicle.
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