... The only they can cause overheating is if they are bad and stick in the closed position.
THERMOSTAT TECH 101
As engine technology advances, controlling the operating temperature of the engine becomes even more critical. The computers make many corrections to the engines as the coolant temperature changes.
Late model engines are being constructed with many new alloys that have dissimilar expansion characteristics that are greatly effected by temperature.
... Before the computers were installed in vehicles, the temperature was more important than a lot of people once thought. Some people were removing the thermostats from the vehicles for summer time operation thinking erroneously its removal was a prime factor in preventing the engine from overheating.
... Engines are designed and tested to operate at a particular temperature and the designers prescribe a thermostat with the best opening temperature. The designers also prescribe various engine lubricant viscositys or multi- viscositys for various ambient temperatures for use in their particular engine.
... Few people have given thought to the fact that engine lubricating oil is also used for cooling parts of the engine the coolant can not reach. The oil temperature is cooled by among other things, the coolant and that in turn is controlled by the thermostat.
With the advent of the EPA emissions schedules the engine designers have raised the operating temperatures in order to reduce the emissions. In 1981 AMC Jeeps were equipped with 195 f degree thermostats and now there are vehicles that operate above 212f degrees.
... The engine design people prescribe the quality, operating temperature and the viscosity of the oil to the American Petroleum Institute and a standard is set.
The viscosity of most oils is controlled by heat. The multi viscosity GF-3 rating of present day motor oils such as SAE 10-30 are ’30 weight’ at the operating temperature that the engine designers specified. The SAE 10W-30 viscosity thins as the operating temperature of the oil is lowered. The ’10 weight’ viscosity helps the engine to last longer because the 'thin' oil gets to the moving parts that wear quicker during cold start-up.
... The higher operating temperatures aid in expelling water vapor that entered as the engine was cooling. If the moisture is not removed it can cause sludge, rust and degrade the lubricating qualities of the engine oil.
The flow configuration for the coolant (depending on engine design) is that the water pump pressurizes the block. The block distributes coolant though the cavities into the heads. Block pressure must be consistent from front to rear to insure uniform coolant distribution to reduce steam pockets that can cause water pump cavitation. Less pressure can result in less flow around the rear cylinders. When we boil this fact down it simply means the thermostat is a useful tool in maintaining the pressure. The pressure between the water pump and the thermostat should be slightly higher than the radiator pressure.
If a thermostat suddenly slows the coolant flow, a sudden increase in the water pump differential pressure can happen. The primary cause of cavitation is differential pressure change i.e. sudden change in flow rate.
High quality thermostats that operate smoothly and slowly can reduce the probability of cavitation.
Cavitation can be a major cause of erosion and overheating.
1. Use the manufacturer’s suggested thermostat temperature range.
2. Test to find and repair all leaks.
3. Check and replace pressure caps as needed.
4. Select quality when purchasing water pumps and thermostats.
5. Modifications often lead to problems.
6. Use the manufacturer’s suggested coolant or generic equivalent.
7. Use distilled water to reduce scale deposits.
The amount or volume of coolant changes with its expansion and contraction as the temperature changes. In order to keep the cooling system full at all times the coolant recovery systems were installed in modern vehicles. The pressure cap allows coolant to be drawn back into the radiator as the coolant contracts.
Have a good one
and CUL Don S..