The thermostat in your Mercedes-Benz is a device that is located between the engine and the radiator on all liquid-cooled engines. The thermostat is quite small, measuring out at about two inches in diameter.
The thermostat’s purpose is to block the flow of any coolant to the radiator until the engine has warmed up to a predetermined temperature. As soon as the engine reaches the designated operating temperature (around 200 degrees F), the thermostat will open and allow coolant through to maintain that perfect temperature.
Your thermostat is able to do its job because of the small cylinder that is located on the side of the device that faces the engine. It is filled with wax. The wax in the cylinder melts when the engine reaches around 180 degrees F. When the wax melts, it will expand quite a lot and push a rod out of the cylinder. This will press into the wax and open the valve.
Signs Your Thermostat is Faulty
Poor Engine Performance
Driving a car with a faulty thermostat is like trying to take a long walk in the summer heat with no water. A bad thermostat means your vehicle is not able to cool itself down. An engine that is too hot will perform poorly. You may also notice a significant drop in your vehicle’s fuel economy.
Engine Overheating/Under Heating
Your thermostat is one of the most important parts of your engine’s temperature control system. When not working correctly, the gauge will end up either too low or too high.
If the thermostat gets stuck in the open position, coolant will flow without stopping. If the coolant flows before the engine needs it too, the engine will not be able to reach its optimal operating temperature. As discussed above, when this happens, you can end up with decreased engine performance and fuel economy.
Conversely, if the thermostat gets stuck closed, then no coolant can reach the radiator, and the engine will end up overheating. If the engine overheats for too long, you can end up with a lot of harm being caused to your engine.
If your engine is overheating or underheating, the thermostat is one of the first things you should check.
Fluctuating Engine Temperature
One of the first signs of a faulty thermostat is your engine’s temperature gauge. If you notice it swinging back and forth between hot to cold, you may have a faulty thermostat. This could be due to a thermostat not opening or closing the way it’s designed to do. A thermostat that doesn’t open or close as it should can cause incorrect temperature readings.
Leaking Coolant
One final sign of a faulty thermostat is a puddle of liquid underneath your vehicle. If the valve is not allowing fluid to flow, the surrounding hoses can take on damage, causing them to leak onto the ground. If you do notice fluid on the ground beneath your vehicle, one of the first things you should check is the thermostat.
When to Replace a Thermostat
Generally speaking, a thermostat will not normally become faulty with age. If it appears to be working fine, then there is no need for a new thermostat. However, if you are already having another part of your cooling system worked on, then you might replace the thermostat to be on the safe side. This is especially recommended if you’re already having the upper hose removed, which is where most thermostats are situated. As a rule of thumb, if you’re having any hoses or gaskets or your radiator worked on, ask your mechanic if they believe replacing the thermostat is prudent at this stage in your car’s lifespan.
As far as car parts go, the thermostat is a pretty low-maintenance part. Unless it stops opening and closing as designed, you really don’t have to do any maintenance.
The Best Service Center for Your Mercedes-Benz to Replace the Thermostat
If your Mercedes-Benz is showing any of the signs 
mentioned above, you will want to bring it to our respected automotive center right away. If you live in the Fontana, CA area, Elite BMW & Benz MD’s is the shop for you. Give us a call today to book your convenient appointment. Allow us to earn your business!