Why is antifreeze "rusted" and how dangerous is it for a car?

The correct functioning of the vehicle's power plant is largely determined by the optimal operation of the cooling system with antifreeze circulating in its closed circuit. Maintaining the required temperature regime of a running engine mainly depends on the level and quality of the refrigerant. Having found a change in its color during a visual inspection, you need to figure out why this happened and what measures to take to correct the situation that has arisen. It should be understood whether further operation of the car is possible if the antifreeze has become rusty or it needs to be replaced immediately.

Why did antifreeze become rusty

A change in the color of the refrigerant indicates a problem with the operation of this technical fluid. Most often occurs for the following reasons:

1. Oxidized surfaces of metal assemblies and parts that the liquid washes. This is a common problem in used cars. Rust appears on them, it gets into the antifreeze circulating throughout the system. This changes the color.
2. Substandard antifreeze, without deterrent additives, was poured into the expansion tank. As you know, an overly aggressive liquid easily eats up rubber materials: hoses, pipes, gaskets. In this case, the refrigerant will be black.
3. Using water instead of antifreeze. This happens, for example, on the road, when there is no coolant at hand, and one of the pipes breaks. You have to fill in tap water, which over time will form scale on the walls of the radiator.
4. Antifreeze has lost performance and discolored. Its additives with protective characteristics have ceased to work, the liquid is no longer able to withstand operating temperatures. Foam can form even at 90 ° C.
5. Engine oil has spilled into the coolant. This happens for various reasons, as a rule, the cylinder head gasket dries up.
6. Adding chemicals to the radiator. Some motorists believe in miraculous additives that supposedly quickly eliminate radiator leaks. In fact, there is no benefit from them, but the color of the refrigerant changes greatly, since it reacts with these substances.
7. Antifreeze was changed, but the system was not flushed well enough. Sediments have accumulated. When a new liquid is poured, all impurities are mixed with it, the liquid turns black or becomes cloudy.
8. Defective cooling circuit or oil heat exchanger, which is installed on many powerful cars.

Sometimes the reddish color of antifreeze appears over time as a result of excessive engine loads during a sporty driving style with sharp acceleration and deceleration. Long-term idling in traffic jams in big cities leads to a similar result.

What are the causes of darkening after direct replacement? Mainly to blame for poor-quality flushing of the system. The dirt and impurities remaining on the internal surfaces during the circulation of the liquid change its color. To prevent this, always flush the channels and hoses of the cooling circuit with distilled water or special chemical compounds. During the replacement process, the old refrigerant must be completely drained. You can not add fresh antifreeze to mining, bringing the fluid level to normal.

What to do if the antifreeze has darkened

First of all, you need to determine the exact reason why this happened. If the fluid is contaminated with engine oil, the integrity of the cylinder head gasket and heat exchanger parts are immediately checked. The detected malfunction should be quickly removed, since the combination of the refrigerant with the lubricant leads to engine malfunctions and further costly repairs.

It is easiest to act in a situation when the antifreeze has expired. It will be enough to remove the waste and after a high-quality flushing of the system, pour fresh liquid into it.

The possibility of further use of the refrigerant with a changed color is determined after checking the temperature regime of the operating motor. If the engine does not overheat under load, antifreeze can be used for some time. The coolant should be replaced if it has a strong odor and is black or brown and the engine overheats.

This antifreeze must be replaced.

Step-by-step instructions for replacing antifreeze:

1. Waste fluid is completely drained from the engine cooling circuit.
2. The expansion tank is removed from the engine compartment, thoroughly cleaned of dirt and installed in its place.
3. Distilled water is poured into the system, its level is brought to normal after starting the engine.
4. The car starts to move, after a few kilometers the engine turns off and the flushing fluid is drained from the cooling circuit.
5. These actions are repeated several times until the distillate discharged from the system becomes clean and transparent.
6. After that, fresh antifreeze is poured into the radiator.

How to flush the system except for store products

You can use not only distilled water. Good results are obtained by using the following means:

• composition of 30 g of citric acid, dissolved in 1 liter of water, effectively removes rust from parts;
• a mixture of 0,5 l of acetic acid with 10 l of water qualitatively washes away dirt and deposits;
• beverages such as Fanta or Cola cleanse the system well;
• perfectly removes impurities the milk return poured into the radiator.

Video: flushing the cooling system

Flushing the cooling system.

What can happen if you do nothing

If the performance of antifreeze is lost, its further use will lead to a sharp reduction in the resource of the motor. Corrosion will destroy the pump impeller and thermostat. As a result of overheating, the cylinder head may skew and crack, the pistons will burn out, and the engine will jam. Overhaul of the power unit will have to spend significant funds.

Regular engine maintenance, including timely replacement of the coolant, will increase the engine's resource. Antifreeze color change is not a normal phenomenon. The problem that has arisen must be resolved immediately. Otherwise, you can face much more serious malfunctions, for the elimination of which you will have to spend a lot of time and money.