Discover Everything You Need to Know About Car Thermostats
Cars have become so advanced that we often forget that just like all things they need regular maintenance to work properly. Take the case for the cooling system. You’ll need to regularly check on coolant levels to ensure that it hasn’t evaporated over time or there aren’t any leaks in the system. It’s this that keeps the engine from overheating, and something that can mean expensive repairs down the road.
A large portion of engine failures are caused by two things – the lack of lubrication, leading to grinding metal parts; and cooling system parts that have called it quits. While both can be serious, diagnosing issues on time can save you a lot of hassle. Normal operating temperatures in cars hover around 90 degrees, and both oil and coolant keep these ranges within sane limits.
Auto cooling systems consist of several parts. They work by circulating liquid coolant through hot engine parts. While radiators and water pumps, connected by a series of hoses and valves do most of the work, one engine part, the car thermostat often doesn’t get the credit it’s due. Thermostats perform the simple but vital function of regulating engine temperatures. Think of it as an on/off switch that determines whether coolant is gathering excess heat or not. And while most thermostats are rated to last 10 years or more, some fail early on.
What are Thermostats?
Thermostats are electronic or mechanical devices that measure the temperature of engine coolant. They perform two critical functions. Thermostats open to allow that coolant to circulate through the system, in effect cooling the engine or maintaining it at optimal operating temperatures. Or the thermostat can remain closed, for instance on startup, until that optimal temperature isn’t reached.
The working principle is relatively simple. Both electronic and mechanical thermostats rely on chambers filled with a wax pellet that starts to melt between 75 and 90 degrees centigrade. This engages a spring, that acts on a rod to push open the thermostat valve once the specified temperature (dependent on the composition of the wax) has been exceeded. The process allows for coolant to flow from the engine and into the radiator where it cools. It remains open until the engine is experiencing higher-than-normal temperatures, but the whole process is reversed when things start to cool down. The valve closes, blocking the passage of the coolant.
Types
Electronically-operated thermostats feature in most cars today. They are controlled by the car’s ECU with other temperature-sensing devices (such as a coolant temperature sensor) and offer more control and optimal performance at different engine temperatures. Older cars will have a mechanical capsule thermostat. Compared to electronic variants, these regulate engine heat solely on the expanding and contracting wax inside. As modern engines are downsizing, and working under higher heat and stress (think forced induction), mechanical thermostats offer severely limited engine temperature management. This is the reason why they’re steadily being replaced.
Location of Auto Thermostats
Thermostat housings in most cars are in one of two locations – on top of the engine and connected to the water pump, or lined in the return hose just before the radiator.
Signs that the Thermostat is Losing Its Cool
A thermostat can and will fail, and this causes a disruption to the flow of the coolant in the engine. What follows is that the engine will either get too hot, and parts start to melt or disintegrate, as the thermostat gets stuck in the closed position, preventing coolant from flowing. Or it gets stuck in the open position (valves won’t close) and the engine won’t get up to optimal working temperatures, so performance is compromised, leading to higher-than-usual fuel consumption, engine wear and cold cabin temperatures.
Typical symptoms of a defective thermostat (or related engine cooling parts) are the following:
- Abnormally high engine temperatures – If the engine temperature gauge reaches optimal working temps just a few minutes in the ride, with the temperature steadily increasing even when the engine isn’t stressed, then this can be a sign that there is a problem with temperature management owing to a faulty car thermostat.
- Fluctuations in engine temperature – Variance between hot and cold engine temperatures, with the gauge one minute in the red then abruptly dropping indicates an uncontrolled rise and fall pattern of heat levels. This means that the valve isn’t opening and closing at the right time.
- Leaking or Loss of Coolant- Coolant that gets too hot either evaporates or forms visible patches along hoses, radiators and other parts. Left as is, the coolant may corrode metal parts and cause further damage. A stuck thermostat is often to blame, as the pressure buildup means the coolant will escape the system in any way it can. Visible marks under the car, or the sweet smell of burning coolant are the obvious signs.
Replacing Thermostats
Car manufacturers advise to get an OEM replacement thermostat as this is the same that the car has when new. Or buyers can opt for aftermarket variants, especially if they’ve modified the engine for that extra dose of power. While the parts are easily swapped out (and previously tested) as a simple hands-on job, some people may prefer to get the job done at a qualified mechanic.