Your car’s thermostat might be a small part, but it plays a big role in keeping your engine running at the right temperature. When it fails, your vehicle can quickly overheat—or struggle to reach normal operating temps. Either scenario can lead to poor performance, higher emissions, and in worst cases, engine failure.
At DADS Auto Repair in Madera, we see failed thermostats more often than you might think—especially during season changes or after major engine work. Here’s what happens when a thermostat fails, how to spot the signs, and what to do before overheating causes permanent damage.
What Does the Thermostat Do?
The thermostat is a temperature-sensitive valve that sits between your engine and radiator. Its job is to regulate coolant flow based on engine temperature. When the engine is cold, the thermostat stays closed to help the engine warm up quickly. Once the engine reaches optimal temperature, it opens to allow coolant to flow through the radiator, preventing overheating.
In short, it helps your engine warm up quickly—but not too much.
What Happens When a Thermostat Fails?
There are two ways a thermostat can fail: stuck closed or stuck open. Each causes a different problem.
1. Stuck Closed: Overheating Risk
If the thermostat is stuck in the closed position, coolant can’t circulate to the radiator. This causes heat to build up inside the engine, leading to rapid overheating. In this case, your temperature gauge will rise quickly, and you might see steam coming from under the hood.
Ignoring this can lead to:
- Blown head gaskets
- Warped cylinder heads
- Cracked engine blocks
- Complete engine failure
2. Stuck Open: Poor Efficiency and Cabin Comfort
When stuck open, the thermostat allows coolant to flow constantly—even when the engine is cold. This can cause:
- Longer warm-up times
- Poor heater performance in the cabin
- Reduced fuel efficiency
- Higher emissions
- Poor engine performance in cold weather
While not immediately catastrophic like overheating, a thermostat stuck open can still cause long-term wear and reduced reliability.
Warning Signs of a Failing Thermostat
Catch the issue early, and it’s a simple, affordable repair. Here are the most common symptoms of a bad thermostat:
- Temperature gauge spikes quickly or stays unusually low
- Engine overheats soon after starting
- No heat from cabin vents (even after warming up)
- Coolant leaks around the thermostat housing
- Steam or a sweet smell coming from the engine
- Check engine light with cooling system-related trouble codes
If you notice any of these signs, don’t wait. Thermostat failure can go from minor inconvenience to major damage faster than you think—especially in stop-and-go traffic or hot Madera summers.
What Causes Thermostat Failure?
Thermostats are mechanical devices, and like any moving part, they can wear out. Common causes include:
- Normal age and wear (usually after 60,000–100,000 miles)
- Corrosion from old or dirty coolant
- Overheating events that damage the thermostat spring
- Installing the wrong temperature rating during previous repairs
At DADS Auto Repair, we always inspect the entire cooling system—not just the thermostat—when diagnosing overheating issues.
Why You Shouldn’t Ignore Overheating
Overheating is one of the fastest ways to destroy an otherwise healthy engine. When the thermostat fails and the engine runs hot, metal components expand and warp, head gaskets can blow, and internal engine parts can seize.
Repairing a cooling issue early might cost a few hundred dollars. Waiting until your engine overheats could cost you thousands.
If your temperature gauge rises quickly or your heat suddenly stops working, pull over and shut off the engine. Then call a trusted shop like DADS Auto Repair in Madera for help.
How We Fix Thermostat Issues at DADS Auto Repair
When we suspect a faulty thermostat, our team starts with a complete inspection of the cooling system. That includes:
- Checking coolant levels and condition
- Monitoring temperature rise and fall
- Pressure testing for leaks
- Inspecting the thermostat housing and radiator hoses
- Verifying radiator fan operation
- Running a diagnostic scan for any related codes
If the thermostat is sticking or showing signs of failure, we’ll replace it with a high-quality OEM or better part and refill the system with the correct coolant.
We also look at the big picture. If the thermostat failed due to old coolant or debris, we may recommend a coolant flush to help protect your entire cooling system moving forward.
Preventing Future Thermostat Problems
A little prevention goes a long way. Here are a few simple tips:
- Replace the thermostat as part of scheduled cooling system maintenance
- Flush your coolant system every 3–5 years or 30,000–60,000 miles
- Use the correct coolant type for your vehicle
- Have your cooling system inspected at every oil change—especially before summer or long trips
If you’re unsure when your thermostat was last replaced, we can check your service history and inspect the part itself during your next visit.
Count on DADS Auto Repair for Cooling System Service in Madera
At DADS Auto Repair, we take engine cooling seriously. We’ve helped countless Madera drivers avoid catastrophic damage by diagnosing thermostat issues before they led to failure.
If your engine is running hot, your heat isn’t working, or you’ve noticed any warning signs, give us a call. We’ll inspect your system, explain what’s going on, and recommend the right fix—without guessing.
