Thursday 13 February 2020

Use tap water in Radiator?


Water is an excellent medium for heat transfer. Then why not use plain tap water in the cooling system of the diesel engines instead of the branded Coolants available in the market?

Although water is one of the best mediums for heat transfer, it has got some limitations.

Water will start boiling as soon as the temperature reaches 100oC and will evaporate in the form of steam.
To increase the boiling temperature of water the cooling system is designed as a closed-loop system equipped with a Pressure Cap in the Radiator. The concept is similar to that of a Pressure Cooker. By chance, if there is a leak in the Pressure Cap of the Radiator, the water will evaporate at 100oC, if not refilled in time all the water will vanish and the engine will seize due to high temperature.





Water freezes at 0oC, it will not work in sub-zero ambient temperatures. The water will freeze and block the coolant passages and will also damage the Water Pump.

Water is corrosive when it comes in contact with ferrous metals. It will form rusts throughout the coolant flow paths and eventually choke it. At very high temperature water also corrodes aluminium and copper parts.

The minerals and other impurities present in water also contribute to scale formation along the paths of coolant flow. The fine water tubes of the radiator will get choked severely.



Rust and scale formation completely destroys the cooling efficiency and finally the engine will seize due to lack of cooling. Only a costly and time-consuming engine overhaul service can restore the engine in such cases.

That is why specially formulated Coolants are used in engine cooling systems. Various chemicals are added into the water to make the coolant which is most suitable for the engine.


COOLANT = Water + Anti Freezing Chemicals + Anti Boiling Chemicals + Rust Inhibitor Chemicals


Some brands will sell their coolants as Ready-To-Use (RTU). The benefit of using RTU Coolant is that you don’t have to mix it with water. You simply open the can and pour the coolant directly into the Radiator.



Do not mix different brands of coolant. Before adding the manufacturer recommended coolant flush out the old coolant (if it is of a different brand).


Some brands will sell concentrated or semi-concentrated coolants. In such cases, the user needs to mix the coolant with locally sourced water.

While mixing the concentrated or semi-concentrated coolant with water be careful with the quality of water you choose. Do not use tap water or well water. Water from these sources contains various metals, salts and other impurities and will completely defeat the purpose of your investment in branded Coolants.

Use only DM (Demineralized) water for mixing with Concentrated or Semi-Concentrated Coolants. DM water is not distilled water, it is specially purified water that has had most, or all of its mineral and salt ions removed. It is also known as Deionised water.



All water sources contain various minerals that can eat through aluminium or copper fins of the Radiator. Well water is typically full of iron and very hard. If that well water is softened, still it will contain sodium or salt. Tap water from the local municipal supply will have various amounts of Calcium, Fluoride and Chlorine. These will contribute to Scale formation or leakage.

Only in case of extreme urgency, use water as a coolant. But get the coolant as soon as possible and drain the water completely and refill with coolant as early as possible.

To know more about our products visit us at www.mahindrapowerol.com  or call us at 1800-419-1999  

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