What is the engine operating temperature and why does it rise


Maintaining the operating temperature of the motor is an important task of the cooling system. The mixture formation, fuel consumption, power and throttle response of the engine depend on the temperature of the coolant. Overheating of the motor promises serious problems, up to and including the failure of the entire unit. How to avoid this - you will find out further.

What should be the operating temperature of the engine

It is believed that the normal operating temperature of an internal combustion engine is between 87 ° and 105 °. For each engine, the operating temperature is determined by its own, at which it works 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 an optimal temperature value that does not go beyond the norm.

What is the engine operating temperature 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 a lack of coolant in the system. Coolant, in the form of antifreeze or antifreeze, constantly circulates through the system, removing heat from the heated engine parts. If the coolant level is insufficient, the heat will not be dissipated enough, which means that a rise in temperature 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, top up with plain or distilled water, after which the cooling system must be flushed, and then filled with fresh antifreeze. At t ° above 90 degrees, immediately stop the car and turn off the ignition, let the engine cool down.

Failed electric cooling fan

The electric fan blows cold air onto the radiator, which is especially necessary when driving at low speeds 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 serviceability. Reasons for fan failure:

  • the electric motor is out of order
  • oxidized connector
  • fan relay burned out
  • the internal combustion engine temperature sensor is out of order.

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 engine operating temperature and why does it rise

Faulty thermostat

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

  • operating temperature of the coolant 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 whole with a temperature sensor and a pump.

Broken cooling fan belt

On vehicles with a longitudinal engine, the fan can be driven by a drive belt from the crankshaft pulley. In this case, the fan works forcibly. Drive belt resource from 30 to 120 thousand. km. Usually one belt drives several nodes. When a 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 driven fan, it is recommended to install an additional electric fan in order to avoid unpleasant cases.

Dirty radiator

What is the engine operating temperature and why does it rise

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

  • untimely replacement of antifreeze
  • the use of low-quality liquid
  • application in water system
  • the use of a 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.

Causes of low engine temperature

An underestimated engine temperature can be in the following cases:

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

If you purchase antifreeze concentrate, then it must be diluted with distilled water. If in your area the temperature dropped to a maximum of -30 °, then purchase 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. The liquid circulates in the system due to the pressure generated by the pump (water) pump. The working 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 rear fenders "ears" are used, through which the air flow enters the engine compartment and maintains the temperature of the internal combustion engine normal. Many motorcycles also have air-cooled motors through the use of fins on the cylinder head and pallets that remove heat.


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1 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.

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