What is a thermostat?

airdrie thermostatEvery gasoline and diesel engine contains a thermostat. The thermostat’s job is to control the  temperature of your engine, by regulating coolant flow out of the engine and through the radiator.

When the thermostat opens, coolant is allowed to flow through a hose into the radiator, which cools the engine. When the thermostat closes, that flow is blocked, and the engine heats up. Each vehicle’s thermostat is designed to open at a certain temperature, usually between 75°C and 100°C. Your thermostat opens and closes over and over as you drive, always trying to keep your engine at that perfect temperature.

Maintaining the engine at a constant temperature decreases wear; increases fuel economy; and reduces emissions.

What is a faulty or sticking thermostat?

A thermostat that no longer opens and closes at the right temperature is considered to be worn out, or faulty. A failed or “bad” thermostat normally causes one of two issues:

  1. If the thermostat opens too early (at too low of a temperature), or sticks open, the engine will not heat up enough. This can cause poor interior heat; increased fuel consumption; and sometimes, your Check Engine light to come on.
  2. If the thermostat opens too late (at too high of a temperature), or sticks closed, the engine will get too hot. This can cause overheating and damage to the engine itself.

Signs or symptoms of a failed thermostat:

airdrie auto repair
If your temperature gauge is staying very low, this may indicate a faulty thermostat.

How do you tell if your thermostat is faulty? Our expert technicians can usually determine fairly quickly if your thermostat is causing any issues you may have, or if your concern is the result of another problem. Here are some common symptoms that may indicate a thermostat sticking open:

  • Poor interior heat (heater blows well, but the air coming out is cold).
  • Your temperature gauge does not rise past the 1/4 mark, even after a long drive.
  • Your temperature gauge rises normally at idle, but drops when you start driving faster.

If your thermostat sticks closed instead, you’ll have the opposite problem: your engine will overheat. Overheating can be a more complex issue to diagnose, though, as there are a dozen or more potential reasons why an engine could run hot. While we always hope for a simple fix like a faulty thermostat in these cases, the reality is that only about 10% of the vehicles we service for overheating issues need a new thermostat; most of them have other problems. If your engine is overheating, we recommend having us diagnose the issue properly.

Poor interior heat from a failed thermostat:

car heater repair
If your temperature gauge stays around the halfway point, you likely do NOT need a new thermostat.

Every winter, we hear from dozens of Airdrie drivers who would like their thermostat replaced, because their car’s heater is not working very well. Being the honest guys that we are, we don’t just replace the part and take their money; we usually do some testing to ensure the thermostat will actually fix their problem!

If your engine is not heating up normally – as indicated by your temperature gauge – then this is the first place to start in pursuit of better interior heat. However, if your temperature gauge is rising normally and your heater still blows cold, there’s probably something else going on, and a new thermostat will not fix your problem. Poor interior heat could also be caused by a low coolant level; plugged or restricted heater core; poorly circulating water pump; a faulty temperature door actuator; a problem with the heater control system; or several other possibilities. In this situation, the most cost-effective solution would be to have us provide an accurate, honest assessment of your heating system first.

Replacing a thermostat in Airdrie:

airdrie mechanic
An example of a thermostat that is only available as part of a complete housing.

Replacing a car’s thermostat is a fairly simple job most of the time, providing you are somewhat mechanically inclined. (Some vehicles can be trickier than others, though, as some thermostats are located in really tough spots!) Your thermostat is usually located underneath a removable thermostat housing, which is normally located close to one of the radiator hoses. On some newer vehicles, the thermostat is only available as part of a complete housing, and the whole assembly must be replaced.

After a new thermostat is installed, it’s crucial to properly bleed all of the air from the cooling system. If trapped air causes a blockage in the system, the engine will overheat and could damage other cooling system parts. This bleeding process can be rather time consuming on some vehicles.

If you would like us to replace your thermostat, or just troubleshoot your cooling system, give us a shout! We only install genuine OEM thermostats whenever available, as they have proven to be more reliable than aftermarket units. Following a high quality install, we will fill your cooling system with genuine OEM coolant, and back the repair with the best warranty in Airdrie!