Can the Thermostat Be Removed in Summer?

[LeElliott]

It can be removed but there will be impacts, as it will affect the engine's ability to quickly reach its optimal operating temperature. Here is some relevant information about the thermostat: 1. Instrument Introduction: The thermostat automatically adjusts the amount of water entering the radiator based on the coolant temperature, changing the water circulation range to regulate the cooling system's heat dissipation capacity, ensuring the engine operates within the appropriate temperature range. 2. Working Principle: The most commonly used thermostat is the wax-type thermostat. When the coolant temperature is below the specified value, the refined paraffin in the thermostat's temperature-sensing body remains solid, and the thermostat valve, under the action of the spring, closes the passage between the engine and the radiator. The coolant then returns to the engine via the water pump, performing a small circulation within the engine.

[SanRachel]

Honestly, you shouldn't remove the thermostat even in summer. Last week, I repaired an old Jetta whose owner thought removing it would improve cooling. Instead, the temperature gauge went haywire, and fuel consumption jumped from 8L/100km to 11L/100km. Without the thermostat, coolant flows directly into the radiator's main circuit, keeping the engine too cold. The oil thickens like syrup, doubling crankshaft bearing wear. The heating system also suffers, blowing lukewarm air. It's worse for fuel-injected cars—the ECU detects abnormal coolant temps, triggering the check engine light and limiting power like an 80-year-old climbing a hill.

[DelilahLynn]

I also had the idea of removing the thermostat when I was younger, but I learned my lesson the hard way. Last summer, I was driving long distances with the AC on, and even though the water temperature seemed normal, the engine noise was unusually loud. A seasoned mechanic checked it and found that the previous owner had removed the thermostat. He explained that during low-temperature operation, the gap between the piston rings and cylinder walls becomes too large, causing the metal collision noise to be so pronounced. Nowadays, new cars have precise temperature control. After removing the thermostat on my China VI-compliant car, the exhaust emissions exceeded the standard by three times, and it directly failed the annual inspection with a red light.

[KateFitz]

Having run an auto repair shop for twenty years, I've seen plenty of cars with their thermostats removed. These vehicles commonly suffer from fuel dilution in the engine oil, as low temperatures cause incomplete gasoline combustion, allowing condensed fuel to seep down the cylinder walls into the oil pan. Last week, a CRV with its thermostat removed experienced cylinder scoring after just 50,000 kilometers. Modern engines operate optimally at around 90°C. Without a thermostat, it takes half an hour to warm up in winter, and even in summer, temperatures often hover around 60°C—like trying to run while wearing a heavy winter coat.

[StLillian]

Don't listen to those who say removing the thermostat in summer can cool down the engine. The consequences of excessively low water temperature are even more severe. When the engine is cold, the ECU will forcibly enrich the fuel injection, and actual tests show an extra 1.5 liters of fuel burned per 100 kilometers. My neighbor's SUV ran without a thermostat for half a year, and the exhaust pipe dripped water like a faucet. The auto repair shop found that the unburned gasoline had damaged the catalytic converter. Nowadays, turbocharged cars are even more delicate; large temperature fluctuations can cause cylinder head deformation, and the repair cost is enough to buy three new thermostats.

[SanAriana]

At the last gathering, Old Li, who runs an auto repair shop, shared a case: a Sylphy used for ride-hailing had its thermostat removed, and three months later, the engine required a major overhaul. Upon disassembly, it was found that the back of the valves was coated with carbon deposits as thick as rock sugar, and the piston rings were stuck, causing oil burning. The reason was that the low temperature prevented the gasoline from fully vaporizing, and liquid fuel droplets washed away the lubricating oil film on the cylinder walls, resulting in dry friction. Nowadays, many cars have the thermostat integrated into the thermostat housing, and removing it requires draining the coolant. Improper operation can also introduce air, leading to falsely high coolant temperature readings.