#1 Car thermostat. Principle of operation and malfunction
The first entry will be about the thermostat. Probably everyone knows everything about it, but it doesn’t hurt to refresh your memory about it.
All cars in which the engine is cooled by fluid have a small device called a thermostat in the cooling system. It is located between the engine and the radiator. This article tells what a car thermostat is, the principle of its operation and device, as well as what are the malfunctions when the thermostat works.
Car thermostat – what is it?
The thermostat is a temperature regulator of antifreeze (toluene) in the engine cooling system. It accelerates the warming up of the engine and maintains the desired thermal mode of operation.
The thermostat’s main task is to block the flow of coolant to the radiator before the engine warms up. When the engine is cold, no coolant flows through it. When the engine reaches an operating temperature of 95 degrees, the thermostat opens. The thermostat allows the engine to warm up faster, thus the thermostat reduces engine wear and harmful emissions.
If you’re interested, you can take a look at how the thermostat works. It’s quite informative. Put the thermostat in a pot of water and put the pot on an electric stove. As the water in the thermostat comes to a boil, the valve will open about 2 cm. The experiment is better done with a new thermostat, not from your car.
Design and operation of the thermostat
The car thermostat is made of brass and copper. The principle of operation of the thermostat lies in a small cylinder, which is located on the side turned toward the engine.
This cylinder contains a ball of artificial wax that begins to melt at a temperature of 82 degrees Celsius. The wax is chosen because it can expand considerably as it changes from a solid to a liquid state under the influence of heat.
A pin is pressed into the wax cylinder and connected to the valve. When the wax melts, it expands considerably and pushes the pin out of the cylinder, thereby opening the valve. Through the open thermostat, coolant flows through the radiator. When the engine shuts down, it cools down and the wax in the thermostat solidifies, becoming solid again.
What are some thermostat malfunctions?
The thermostat is a small but very important part. A poorly functioning thermostat can keep you on the side of the road. The thermostat can fail for many reasons, but the most common cause is corrosion.
If the thermostat is jammed in the fully closed position – the engine can overheat in almost any driving mode at any positive air temperature and even in light frost. If the thermostat opens, but not all the way, the engine overheats, but may not “boil” – it all depends on the mode of operation of the car.
If the thermostat valve “hangs” in fully or partially open – the engine will warm up to working temperature very long, and in winter, the working temperature may not be reached. With serviceable cooling system at an air temperature of zero degrees, the engine should warm up to working temperature when driving for 5-10 minutes. If the thermostat is not fully open, the engine temperature will not rise above 70 degrees, even in the summer.
How can you tell if the thermostat is working or not?
To do this, you need to warm the engine, but so that the temperature arrow did not reach the red line a little. Then you need to turn off the engine, open the hood, find the upper radiator hose. It is a black rubber hose about 5 cm in diameter with a metal clamp at the ends. The upper hose is attached to the top of the radiator.Then you need to find the lower hose. It looks the same as the upper hose. The bottom hose is attached to the bottom of the radiator.
Touch the hoses, but be very careful as they can be very hot. If the engine temperature gauge shows that the engine is hot and one hose is hot and the other is cold, the thermostat valve is probably closed and the coolant is not flowing through the radiator. The thermostat should be replaced with a new one.
There is another “folk way” to check the thermostat for proper operation. The point is that we must put the thermostat in a vessel with burning (temperature about 100 degrees) water. Then we look visually – if the thermostat valve opens – it works. If not – the thermostat is not working and replace it with a new one. This method involves removing the thermostat from the car.
Also, when replacing the thermostat, you should find out the opening temperature of the valve. Different car thermostats can be different and vary in a very wide range. And as you understand, you can not put the thermostat with a high opening temperature, because the engine in this case can overheat.
Thermostat for the car – how it works
In the engine of a modern car there is a device called a thermostat. Let us tell you what it is and what functions it performs. How to determine whether it is serviceable or not – ways to check it.
What is it
Thermostat – automatic temperature regulator of antifreeze or toluene in the engine cooling system. It accelerates the warming up of the motor and maintains the desired thermal mode of operation.
It is essentially a valve with a temperature-sensitive element inside that blocks the flow of coolant through the radiator until the engine is warmed up. When the engine is cold, no coolant flows through the thermostat and radiator of the car. When the engine reaches the optimum temperature of 75-90°C, the thermostat opens. This allows the engine to warm up more quickly to reduce wear and tear and cut down on harmful emissions.
When the antifreeze becomes warmer than 75 degrees, a special valve in the thermostat slowly opens. It will fully open at about 90-95°C. Between 75-90°C, the thermostat valve controls the amount of coolant flowing through the radiator. It diverts it to the upper radiator tank and water pump. This regulates the optimum engine temperature.
Modern vehicles use single-valve thermostats with a solid filler made of so-called cerezine (hydrocarbon technical wax). When heated, this wax expands and presses on the main valve. Thus the antifreeze flows through the device.
What does the thermostat consist of
- Body (made of copper, brass);
- copper cylinder inside with filled active mass and a thermosensitive element;
- two inlet ports (small and large circle) and one outlet port;
- The main valve and the by-pass valve of the small circle.
What kinds of malfunctions can occur
Jammed in fully closed position
It is possible to overheat the engine of the car in any mode of movement at any air temperature and even in a small frost. In this case, it is replaced with a new one. When it opens, but not all the way, the engine overheats, but may not “boil” – all depends on the mode of operation of the car. In any case, replace it with a new one as soon as possible.
“Hanging” in a fully or partially open state
It will take a long time for the engine to warm up to operating temperature, and in winter – will not warm up at all. With serviceable cooling system at about zero degrees the engine warms up to working temperature when driving for 5-10 minutes.
In the case of incomplete opening – the temperature will not rise above 70°C. In summer it will not cause much trouble, but in winter the heater will not work.
How to determine if it works or not
Usually the thermostat fails gradually . If in summer the malfunction is difficult to notice, in winter it is reflected in the long warming up of the car. When before the car warmed up quickly and it was warm in the cabin – everything is fine. If in winter it was not so comfortable, the arrow of temperature indicator did not reach the working range (from 75 to 95°C) – so there are problems with cooling system. Let’s tell you what are the ways to check the thermostat.
It is necessary to warm up the engine so the temperature doesn’t reach the red zone on the dashboard gauge. Then turn off the ignition, open the hood, find the upper radiator hose. It is attached at the top and is a black rubber hose about 5 cm in diameter. Find the lower hose, it looks like the upper hose. Touch the hoses, but be careful as they may be hot.
If the engine temp gauge shows it is hot and one hose is hot and the other is cold, most likely the thermostat valve is closed and the coolant is not flowing through the radiator. Replace the thermostat with a new one.
There is a popular way to check the thermostat. You need to put the thermostat in a vessel with burning (temperature about 100°C) water. Look visually, the valve opens – it works. If no – not working. This method involves removing the thermostat from the machine.
Video – check the work
When replacing the thermostat of your car, you must know the opening temperature of the valve (buy a non-original) – it can vary in a wide range. As you understand, you can not put the thermostat with a high opening temperature, because the engine will start to overheat.