What is a car thermostat
The automotive thermostat is an intelligent temperature control device in the engine cooling system . It automatically adjusts the coolant circulation path based on the principle of thermal expansion and contraction of paraffin to ensure that the engine always operates within the optimal temperature range of 85-95℃.
Core functions and working principles
The thermostat dynamically controls the flow of coolant like an "intelligent valve"
Youdaoplaceholder0 At low temperatures (<80℃) : Close the large circulation channel, and the coolant only circulates small within the engine to accelerate the temperature rise to the working temperature.
Youdaoplaceholder0 At high temperatures (≥82℃) : Gradually open the large circulation channel, and let the coolant flow through the radiator for heat dissipation to prevent overheating.
Youdaoplaceholder0 Regulation principle : The internal paraffin expands when heated, pushing the valve to open and close, achieving stepless temperature control (for example, the Cruze model switches between 70 and 80℃).
Key roles and values
Youdaoplaceholder0 protect the engine :
Reduce cold start wear: When the temperature is low, the oil viscosity is high, and the thermostat shortens the warm-up time, reducing mechanical wear by 30%.
Prevent high-temperature damage: Avoid faults such as cylinder block deformation or piston sticking to the cylinder.
Youdaoplaceholder0 improve energy efficiency :
Reduce fuel consumption: Maintaining the optimal temperature ensures more complete fuel combustion, saving 5% to 15% of fuel.
Enhanced power: Avoid poor atomization caused by low temperatures and ensure more stable output.
Youdaoplaceholder0 auxiliary system support :
Provide a stable heat source for the warm air of air conditioners in winter.
Fault Impact and Maintenance
Youdaoplaceholder0 common fault manifestations :
Stuck shutdown: A sudden surge in water temperature and the alarm light coming on May cause cylinder pulling.
Stuck startup: Water temperature is too low, fuel consumption increases by 25%, and the heater fails.
Youdaoplaceholder0 Maintenance suggestions : Check every 20,000 to 30,000 kilometers and replace in a timely manner if any abnormality is found (brands such as Mahle and Platinum are compatible with most models).
The main type of thermostat used is the wax thermostat. When the cooling temperature is lower than the specified value, the refined paraffin in the thermostat's sensing body becomes solid. Under the action of the spring, the thermostat valve closes the channel between the engine and the radiator. The coolant is returned to the engine by the water pump for a small circulation within the engine. When the temperature of the coolant reaches the specified value, the paraffin begins to melt and gradually turns into a liquid. Its volume increases accordingly and compresses the rubber tube, causing it to contract. While the rubber hose contracts, it exerts an upward thrust on the push rod, and the push rod exerts a downward counterthrust on the valve, causing it to open. At this point, the coolant passes through the radiator and the thermostat valve, and then flows back to the engine by the water pump for a large circulation. Most thermostats are arranged in the water outlet pipeline of the cylinder head. The advantage of this is that the structure is simple and it is easy to remove air bubbles in the cooling system. The drawback is that the thermostat frequently opens and closes during operation, causing oscillation. A malfunctioning car thermostat can lead to the failure of engine temperature control, causing abnormal water temperature, increased fuel consumption, and even engine damage, which requires timely maintenance.
The function and fault types of the thermostat
The thermostat is a key component of the cooling system. It automatically adjusts the circulation path based on the temperature of the coolant: when the temperature is low, the large circulation is turned off, allowing the coolant to circulate small inside the engine to quickly heat up. After reaching the working temperature (usually 80-95℃), start the large circulation and cool down through the radiator to prevent overheating. Faults are mainly divided into two types:
Youdaoplaceholder0 stuck in the always-on state : The coolant continues to circulate in large quantities, causing the engine to warm up slowly and the water temperature to be too low.
Youdaoplaceholder0 stuck in the normally closed state : the coolant cannot enter the large circulation, and the engine heat cannot be dissipated, which can easily cause the water temperature to be too high or even "boil over".
Fault symptoms and impacts
Thermostat failure can manifest through various phenomena and cause chain damage to the engine:
Youdaoplaceholder0 abnormal water temperature :
Constant on fault: The water temperature gauge remains below the normal scale for a long time, especially in winter when the temperature rises extremely slowly.
Normally closed fault: The water temperature rises rapidly until the alarm light comes on, but the radiator fan may not rotate.
Youdaoplaceholder0 performance and fuel consumption issues :
Low temperatures lead to incomplete fuel combustion, resulting in a significant increase in fuel consumption.
The engine may experience idle vibration, power reduction or abnormal noise due to unstable temperature.
Youdaoplaceholder0 risk of long-term damage :
Frequent operation faults: Low temperatures accelerate engine wear, easily form carbon deposits, and shorten engine lifespan.
Normally closed faults: High temperatures may cause serious mechanical failures such as damage to the cylinder gasket and cylinder pulling.
Diagnosis and treatment suggestions
If you suspect that the thermostat is faulty, you can make a preliminary judgment through the following steps
Youdaoplaceholder0 Observe the water temperature gauge : if the water temperature does not rise for a long time or surges rapidly after starting the vehicle, it is abnormal.
Youdaoplaceholder0 Check the radiator pipes : after the engine has been running for 3 minutes, touch the upper and lower water pipes of the radiator. If the temperature difference is obvious (the upper pipe is hot and the lower pipe is cold), it may be that the thermostat has not been turned on. If there is no temperature change at all, it may be stuck.
Youdaoplaceholder0 Professional testing : Use an OBD diagnostic instrument to read the actual water temperature data, or have a technician conduct a pressure test.
Handling measures
Youdaoplaceholder0 Replace in a timely manner: After confirming the fault, the thermostat needs to be replaced. It is preferred to choose original factory or brand parts to ensure reliability.
Youdaoplaceholder0 Associated maintenance : When replacing, it is recommended to replace the coolant simultaneously and check the condition of related components such as the water pump and belt.
Youdaoplaceholder0 Regular maintenance : Check the thermostat every 60,000 kilometers or during maintenance to avoid losing the big picture for small gains.
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