Overheating happens!
Cooling systems really matter on internal combustion engines. They burn fuel to extract energy to turn the wheels. Waste goes out the exhaust as gas (and heat) and plenty gets dissipated as heat energy via the cooling system.
But stuff goes wrong, and engines overheat. If it hasn’t happened to you or someone you know, consider yourself lucky- at least so far!
Cooling systems are like crumbling rock faces. They start out new and solid, and then over time they gradually deteriorate and crumble. This sounds dramatic but it’s the truth. The nature of the process means that a fluid is involved, and it needs to be rapidly circulated and under pressure. It needs to have an interface with outside air to dissipate heat. All this is happening through many, many heat cycles from hot to cold, and in the real world of rain, dirt, vibration, etc.
Here is an example for you. A while back, I changed the fan belt on my old 1997 Prado. The top radiator hose inlet SNAPPED OFF IN MY HAND. I was just pressing down lightly from above for balance as I was reaching into the engine bay. It came away from the top tank like it was never connected. Admittedly, it was an older vehicle (and possibly the original radiator). BUT if it had happened while I was towing my camper up the big hill at Cape Tribulation, I would have been walking home. Oh, yes, except I have an Engine Guard so I would have been warned!
This is a common fail point on plastic/allow radiators. The heat breaks down the plastic and the cracks are often not visible. This is not the only weak point on these radiators; normally they also leak and then fail at the joints between the plastic tanks and the alloy core. Full alloy radiators tend to be more durable, but they can still crack at welded seams, etc
If you take a close look at the cooling fins on a typical modern alloy radiator core, the metal is very, very thin. I have had a padlock (fallen off a truck driving in front..) put a hole in a 2-core radiator on a Mazda MX5 back in the 1990’s.. Luckily, I saw it happen and we pulled over immediately. The metal was probably better back then. On a brand new cheap radiator, it would probably go straight through….
Over time, the various components corrode, suffer from vibration, repeated expansion and contraction with heat cycles, etc, etc and these all take their toll on the plastics, rubber, alloys and the metal of the engine itself.
The point is: cooling systems are frail, and prone to failure.
And you may or may not be aware, but if you have a serious leak or total failure, the factory temperature gauge PROBABLY WON’T RESPOND! This is because the factory temperature sender is no longer immersed in coolant! If anything, it is likely to drop in temperature….
That’s why you need an Engine Guard. Our’ sensor bolt directly to the cylinder head- so coolant or no coolant, if your engine is getting hot, you will get warned – loud and clear!
