Common thermostat-related problems and how to prevent them


The thermostat’s importance cannot be overestimated. This small component not only regulates the engine’s operating temperature, preventing the engine from overheating; it also accelerates engine warm-up, improves cold-weather usability and even increases fuel efficiency. Therefore, thermostat failures are not to be treated lightly. In this article, we shine a light on the most common thermostat-related problems, making sure you know how to spot and solve them – or, even better, prevent them. 

Two types of thermostats, two types of problems?

Thermostats come in two main types. Most vehicles are equipped with a traditional thermostat, which contains a temperature-sensitive wax element that expands when heated, prompting the piston to move and opening the valve. In addition, there are map-controlled thermostats with an integrated heating resistor in their wax element. This resistor is controlled by the engine’s electronics, which can cause the valve to open preventatively, ensuring an even more accurate engine warm-up. 
Yet, these two types of thermostats do not display different failure symptoms: the problems you can encounter are the same for both. Here are the most important ones...

Old coolant in the cooling system, or the wrong type

The engine cooling system contains coolant, and there are a few things to keep in mind to prevent problems. First of all, coolant needs to be changed at least every five years. Second, coolant types are not interchangeable. Every type of coolant has its own specifications and technology. Mixing coolants using different technologies results in insufficient corrosion protection. Corrosion in the engine system, in turn, can cause a multitude of problems, such as: 
Surface scaling, which leads to reduced heat transfer
Damage to the mechanical seals
Blocked water passages
Perforation, creating leakage
Incorrect coolant system temperature
So, if you are not sure which coolant you have used, you will need to flush the entire cooling system and renew the coolant. Always remember that the use of the wrong coolant can facilitate boil-over, freezing, cavitation pitting, rust or corrosion build-up, or even hose leaks. 
thermostat problems     thermostat problems

A stuck thermostat valve

If you are having problems with the cooling system, you need to check the thermostat valves. As you know, the thermostat valve is designed to open when the coolant reaches a certain temperature. lf a thermostat gets stuck in the open position, the frame breaks and the thermostat valve can no longer be fully closed. This leads to a steady flow of coolant into the radiator, overcooling the engine – a situation that results in poor warm-up and heater performance, increased engine emissions and reduced fuel economy. 
lf, by contrast, the wax element has been damaged by corrosion or a mechanical failure, such as a broken thermostat spring, then the thermostat will become stuck in a closed position. As a result, the flow of coolant into the radiator is blocked, potentially overheating and damaging the engine. This scenario does a lot of damage to the car and is very expensive to fix, so we recommend that you always change the thermostat at the same interval as the water pump and timing belt.  

Air bubbles in the cooling system

Changing the coolant is a process that needs to be done very carefully – both for traditional and map-controlled thermostats. If you do not refill the coolant in the right way after performing any cooling system servicing, like changing a thermostat, a coolant hose or a water pump, air may enter to the cooling system. Any time a car leaks coolant, there is a chance of air getting into the cooling system, and the presence of this air may cause overheating problems or a failure of the engine temperature sensor, which subsequently sends the wrong cooling temperature data to the engine control unit. If the car’s cooling system has bleeder valves, it is easy to solve this problem. You only need to open the bleeder valves until all the air is released and you see fluid coming out. 

Gates Power Clean flush tool: preventing cooling system problems

A lot of cars suffer from improper cooling, either because the coolant has deteriorated over time or because it has become contaminated by damaging deposits (abrasive particles and foreign materials). If you do not properly flush the complete cooling system, dangerous levels of these contaminants can remain inside, which may lead to the premature failure of newly-installed parts. The best solution for keeping these problems at bay is to flush the cooling system and remove all debris with our Power Clean flush tool, which operates solely on clean water and compressed air (so there are no harmful chemicals or solvents involved in the process). 
thermostat problems 
Curious to see how the Gates Power Clean flush tool works? Watch it in action in this video.