What to do if a coolant in your car has completely run out

Sometimes you can see a light flashing on the dashboard warning of the engine overheating. You get out, open the hood and see that there’s not a drop of coolant in the system. It’s gone because of a hole in the radiator. Pierced by some sliver, and there it is – the leak.

Never ever open the radiator cap of the overheated engine! It is extremely dangerous! Operating temperature of modern engines starts with 100°C which is achieved by the integrity of a system, connected to coolant expansion tank through a relieve valve, and its operation under increased pressure. Even if the car is fully operational, opening a radiator cap of an engine warmed to the operating temperature you risk scalding yourself with boiling fluid. Because due to the opening of the cap and the pressure drop which follows it, the overheated coolant boils instantly. If on top of that the engine is overheated, steam scalding is a very real possibility!

So stick to the ironclad rule: never check the condition of the cooling system by opening the radiator cap. Touch the radiator first and make sure it is not too hot. If it is hot – give it at least a quarter of an hour to cool down to a below the steam point temperature.

So the case of a sliver is a much easier one: a puddle under the radiator and the fluid dripping from it – it’s a diagnosis. All that could scald you has already run out.

There are two solutions to this situation.
The first one is to try and seal up the hole with soap, if there is one in the car. Odd enough, but it’s quite a reliable sealer for small sized holes.

The other solution is to pour all the liquid at your disposal (water preferably) into the radiator, and go for it with your head held high, replenishing the water reserves at every reservoir on your way.

The hardest part with this is that many car owners, fascinated by the words: “Coolant performs lubricating functions”, keep away from filling the system with anything other than the coolant itself. Meanwhile, using ordinary water instead for a few days will do the engine no harm.

If after all there still remains some coolant in the cooling system, touch the radiator with caution. A cold radiator wherein the engine is overheated (not just hot!) is a sign of thermostat failure. It is easily removed (usually it is situated in the upper hose connected to the radiator) and can be moved on without it.

If you don’t feel like poking around in the engine or you lack the necessary tools, just lower the side windows and turn on the compartment heater at full power. The heater has its own coolant circuit that is bypassing the thermostat and will drain some of the heat. However, its power is much less than that of primary radiator; therefore you should drastically reduce the engine load (slowing down, less throttling on the rough road) and monitor the temperature, which will obviously go up. Having reached a dangerous point, stop the car and allow the system to cool down.

But first and foremost when the engine is overheating check the water pump belt: whether it’s intact, whether it slips (which you could have guessed from an outworldly screeching).

Another instance is possible as well. Judging by the look of it, everything is running just fine. Coolant tank is full, the belt provides necessary tension, the radiator is heating, the cooling fan is desperately waving its blades. But the engine is still heating. That happens when the water pump vane wears out. Or the thermostat is stuck in an in-between position. All in all, you better figure it out at a garage or a repair shop without unnecessary panicking.

This failure is not a particularly expensive and dangerous one, and the driving is quite possible, subject that you don’t drive like a lunatic, don’t push the pedal to the metal and keep the heater on at max power. Simply put – do not push the engine to its limits.

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