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I know that a lack of engine oil can destroy an engine, so I was curious as to whether it is just as bad to drive a car with a very low engine coolant.
What is engine coolant?
What exactly are all of the disadvantages to running an engine when the engine coolant becomes too low?
What is engine coolant?
Engine coolant is a water and antifreeze solution. Because water has good properties as a coolant, antifreeze is used in internal combustion engines and other heat transfer applications, such as HVAC chillers and solar water heaters. The purpose of antifreeze is to prevent a rigid enclosure from bursting due to expansion when water freezes.
As the coolant is moved around the system by the water pump, it passes through two main components:
What exactly are all of the disadvantages to running an engine when the engine coolant becomes too low?
Just to clarify, there are no tangible advantages other than saving a tiny amount of money on engine coolant. As you will see, you should never do this due to the knock-on effect that it can cause.
Depending on the make and model of your car some of these may not apply, but in general:
You get less cooling. If the radiator is only 1/2 way full you have water in contact with cooling fins for 1/2 the time and 1/2 the cooling. The fluid is pumped from bottom so it will continue to flow. Eventually the water is hot enough that the engine turns it to steam. Once you empty the radiator then zero cooling as nothing is pumping.
Water flow will stop and the heat will not be able to be transferred out of the engine block. Engines cooling systems are very intricate and feature "pockets" depending on how much cooling is needed for a given area. A lack of coolant means that the system will not be able to be pressurized by the pump and the coolant will not flow.
Disadvantages:
Overheating
Water pump running dry and damaging itself in the process for a lack of lubrication and resistance
My sons 99 LS1 Trans Am started to lose power after running fine to the last gear but then it would lose power and run the rpms 2000 at 35 mph. Yesterday, he stopped on the side of the road because it had a smell like something burning and a little bit of greyish smoke was coming from the back. He let it cool and made it home. No more smoke. When the mechanic looked at it today, there was very little coolant/water in the radiator. He told him that with the low coolant it was telling the transmission it was getting too hot and therefore it wouldn't go faster. He said that smell was burning coolant. He put coolant in it and they took it out up and down the highway and let it warm up and he got on it and it went through all the gears and had plenty of pickup. The mechanic said it should be ok now but keep an eye on it. I told him to watch for any leaks under it when he parked it because the radiator or a hose could have a leak. I am hoping he dodged the bullet with it and will keep up with making sure it has coolant. Im guessing that if the head gasket or block were damaged, there would be some signs. The transmission is shifting smoothly through all the gears.
As the coolant gets lower and lower things will progress as follows:
Some engines require purging to remove air pockets from the cylinder head after the coolant level is restored. This may require revving the engine up momentarily.
Engines with aluminum cylinder heads on iron blocks are highly susceptible to head gasket damage when over heated, due to the differing rates of expansion of the different metals. Avoid running them even if the temperature gauge shows a minor overheat.
NOTHING will happen if that lower amount wont cause overheating. For example in my country winters are very cold about minus 32 degrees Celsius. My car to get warm it takes about 30 minutes. It's Italian car and it very bad at warming up in winter. So i use less amount of coolant so this amount heats faster. And impossible to overheat car because when thermostat opens cold coolant from radiator makes coolant cold again and car never overheats. People here just makes worst scenarios. witch is not possible if your coolant temp is in normal range - 90c. Also fairy tales about water pumps is stupid. Water pump is just bearing that is driven by belt. Bearing rotates plastic stuff that makes water flow. Maybe in other cars it's different in mine there is no actual pump. SO if there would be no coolant, which is impossible based on your question - it wont broke.
