What is the operating temperature of the engine and why does it rise


Maintaining the operating temperature of the motor is an important task of the cooling system. Mixing, fuel consumption, engine power and throttle response depend on the coolant temperature. Overheating of the engine promises serious problems, up to the failure of the entire unit. How to avoid this - learn further.

What should be the operating temperature of the engine

It is believed that the normal operating temperature of the internal combustion engine is from 87 ° to 105 °. For each engine, the operating temperature is determined by its own, at which it operates most stably. The power units of modern cars operate at a temperature of 100 ° -105 °. In the engine cylinders, when the working mixture is ignited, the combustion chamber heats up to 2500 degrees, and the task of the coolant is to maintain the optimum temperature value that does not go beyond the norms. 

What is the operating temperature of the engine and why does it rise

Causes of engine overheating

Overheating can be caused by many reasons, all of them are associated with a malfunction of the cooling system, or the quality of the coolant, as well as contamination of the cooling system jacket, which impairs the fluid's capacity. It is important to use quality spare parts, otherwise the following reasons will happen suddenly. Let's consider each of the reasons.


Low coolant level

The most common problem is the lack of coolant in the system. Coolant, in the form of antifreeze or antifreeze, constantly circulates through the system, removing heat from heated parts of the motor. If the coolant level is insufficient, the heat will not be sufficiently removed, which means that temperature increase will be inevitable. 

If it is not possible to add coolant, then turn on the stove to reduce the likelihood of overheating. In extreme cases, add regular or distilled water, after which the cooling system must be washed, then pour fresh antifreeze. At t ° above 90 degrees, you should immediately stop the car and turn off the ignition, allow the engine to cool. 

Failed electric cooling fan

The electric fan pumps cold air onto the radiator, which is especially necessary when driving at low speed, when there is not enough air flow. The fan can be installed both in front and behind the radiator. If the temperature arrow starts to rise, stop the car and check the fan for proper operation. Causes of fan failure:

  • motor failed
  • oxidized connector
  • fan relay burned out
  • The engine temperature sensor has failed.

To check the fan, remove the connectors from it, and “throw” the wires directly to the battery, which will determine the cause of the failure.

What is the operating temperature of the engine and why does it rise

Thermostat malfunction

The thermostat is one of the main elements of the cooling system. The cooling system has two circuits: small and large. A small circuit means that the fluid circulates only through the engine. In a large loop, fluid circulates throughout the system. The thermostat helps to quickly set and maintain the operating temperature. Thanks to the sensitive element, which opens the valve at 90 degrees, the liquid enters a large circle, and vice versa. The thermostat is considered faulty in two cases:

  • working t ° of a cooling liquid is not reached
  • the power unit tends to overheat.

The thermostat can be located directly in the cylinder block, in a separate housing, or as a unit with a temperature sensor and a pump.

 Cooling fan belt break

For vehicles with a longitudinally mounted engine, the fan can be driven by a drive belt from the crankshaft pulley. In this case, the fan runs forcibly. Resource drive belt from 30 to 120 thousand km. Usually, several nodes are driven by a single belt. When the belt breaks, the internal combustion engine instantly tends to overheat, especially when the speed is reduced. If you have a domestic car with a belt fan drive, it is recommended to install an additional electric fan in order to avoid unpleasant cases. 

Dirty radiator

What is the operating temperature of the engine and why does it rise

Once every 80-100 thousand kilometers it is required to flush the radiator along with the entire cooling system. The radiator is clogged for the following reasons:

  • untimely replacement of antifreeze
  • low-quality fluid
  • water application
  • the use of sealant for the cooling system.

To wash the radiator, you should use special compounds that are added to the old antifreeze, the motor runs on this “mixture” for 10-15 minutes, after which you need to remove water from the system. It is advisable to remove the radiator, rinse it with water under pressure inside and out.


Reasons for low engine temperature

Low engine temperature can be in the following cases:

  • inappropriate thermostat (opening temperature too early)
  • high performance cooling fans, or their forced operation from the moment the engine starts
  • thermostat malfunction
  • non-compliance with the proportion of mixing antifreeze with water.
What is the operating temperature of the engine and why does it rise

If you get antifreeze concentrate, then it must be diluted with distilled water. If in your region t ° decreased, up to a maximum of -30 °, then get antifreeze marked “-80” and dilute it 1: 1 with water. In this case, the resulting liquid will be heated and cooled in time, and also will not lose lubricating properties, which is extremely necessary for the pump. 

The main types of ICE cooling systems

  1. Liquid cooling. In the system, the fluid circulates due to the pressure created by the pump (water) pump. The operating temperature is low due to the control of the thermostat, sensors and fan.
  2. Air cooling. We are familiar with such a system from the Zaporozhets car. In the hind wings “ears” are used, through which the air flow enters the engine compartment and maintains normal engine t °. In many motorcycles, the motors are also cooled by air, due to the use of fins on the cylinder head and pallets that remove heat.
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2 comment

  1. Good evening,
    with complete respect and confidence to reread my case.
    I have a skoda octavia facelift vrs 2.0TDI, 170hp, CEGA motion code from 2011.
    For several months, more precisely since March 2020, I have a problem that I can't find a solution to.
    The car starts and runs flawlessly, but at some point the water sign lights up FOR A FRACTION OF A SECOND and the message CHECK COOLANT MANUALS appears for a second.
    I changed the vessel from the new antifreeze from skoda, I changed the two temperature sensors G62 and G 83, I changed the distribution, I changed the oil and the antifreeze 3-4 times in 1000km.
    It doesn't matter that the antifreeze temperature is 90 times 50, it does this especially when I go more sporty.
    I diagnosed the car at skoda, nothing error 0 appears, I diagnosed while driving and found that the temperature is normal but exactly when it makes that signal the temperature rises for a second to 120 and returns immediately to 117 and returns immediate.
    in the filming it is seen that the needle on board from the water moves tries to get up but because it is short-lived this returns to 90.
    If you've ever encountered something like this, I need help.
    With great respect.

  2. Yes, I suffer this with a Peugeot 207…

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