Along with the radiator cap, the thermostat is the second of the 5 major components that provide system monitoring and control making it a very important component of the system. The operation of a thermostat is controlled by a sealed copper cup containing wax and a metal pellet. As the coolant heats the thermostat, the wax expands pushing against pressure from a spring to open the thermostat and allow coolant flow through the Radiator.

At start up of an ambient temperature engine, the thermostat senses the coolant temperature, which is low, and closes to prevent fluid from passing to the radiator forcing the fluid to re-circulate in the engine until desired operating temperature is reached. When the thermostat senses the coolant, and thus the engine, has reached the desired operating temperature it begins to open to allow some fluid to pass to the radiator for dissipation of heat. The thermostat continues to monitor and adjust as operating parameters and ambient conditions vary to maintain the correct coolant temperature and thus the correct and required engine temperature. Correct engine operating temperature provides more complete fuel combustion and fuel economy, reduced emissions, and burn off of condensation within the engine extending engine life. Therefore, a properly sized and properly functioning thermostat is essential for engine and cooling system performance to the original equipment manufactures’ specifications.

Tips on Car Heating and Engine Cooling

Cooling System Trouble Shooting

Is there a possibility that a thermostat will not provide enough heat to the engine?:  No! A thermostat starts to work only when the engine is hot, which means that the route for the cooling fluid (except for a specified amount of leakage) remains closed. There is no way that a thermostat will add heat to the engine, theoretically and practically, a thermostat prevents overheating of the engine even in the coldest of weather! This is a fact.

In cold weather to get sufficient heat in the car:

  • Check if the heat control is set to the correct temperature.
  • Check if the antifreeze level is correct in the radiator and reservoir tank. Always use good quality antifreeze and preferably distilled water.
  • Check to make sure the hoses to and from the radiator are not clogged.
  • Example: An engine size of 2.0L will reach the right temperature in cold weather -15° C approx. 10-12 minutes after the engine has been turned on or after 4-5 miles (5-7 km).
  • Do not open the heater fan before the engine reaches the right temperature.
  • The thermostat may be stuck open.
  • Always use the recommended OEM thermostat temperature.

Overheating Problems

Overheating problems can occur from:

  • Pure water in the cooling system with a pressure cap more than 4lbs.
  • The coolant not being the right mixture 50% water and 50% ethylene glycol (antifreeze) or (anti boil).
  • A faulty pressure cap (The rubber seals in the radiator caps become dry and develops fine hairline cracks due to heat and lower levels of coolant)
  • A dirty radiator
  • A defective water pump (no circulation in the system)
  • Belts that drive the water pump are loose.
  • When vehicle is on idle position, make sure to check the fan clutch/ electric fan motor are operating properly.
  • A defective fan clutch/ electric fan motor.
  • A defective thermoswitch.

The above are only some of the causes of overheating problems.

A proper thermostat is in the engine to control the heat which occurs from the combustion of the fuel, and it does not add heat to the engine. Overheating will cause damage to the engine and will also damage the thermostat (thermostat burned through) a thermostat itself cannot be the cause of overheating.

The thermostat can be tested by boiling it in plain water for approximately 3 to 5 minutes. If the thermostat does not open, then it must have been damaged (burned through) by the overheating caused by any of the above mentioned reasons.

Every engine must run in a specified temperature, an engine that runs cold (without a thermostat) will use between 10-20% more fuel and the engine will not run properly.

Always match the correct pressure cap to the correct thermostat.

It’s recommended to change coolant every 30,000 miles or 50,000 km, and it is also recommended that the thermostat and the radiator cap should be changed as well.

Use Fail Safe® thermostats and protect your engine from sudden overheating conditions.