Here’s what to do with your radiator in an emergency

You can put water into your car radiator if your engine is overheating, the coolant overflow reservoir is very low or empty, and you have no other option.

You should only do this when you intend to drive a short distance, and you’ll want to ensure that when you arrive you have the radiator flushed and refilled with the correct coolant/water mixture.

Natrad provide you with exceptional coolant products and advice. Nip into Natrad to get the right coolant for your vehicle.

Only Use Water In The Radiator In An Emergency

can i put water in my radiator

If you notice that your engine temperature is rising, you should pull over immediately. Allow the engine to cool and check the coolant overflow reservoir level. If it’s really low or actually empty, you need to add fluid to your vehicle.

While it’s ideal to add a 50/50 mix of coolant and water (or a pre-mixed coolant), if you absolutely have to keep driving, you can add water to the radiator to get you to your destination.

Here are the steps to take to safely top up the coolant in your radiator with water:

  1. Make sure that your engine is off and cool, and the vehicle is in Park or Neutral, with the parking brake on.
  2. Let the engine cool down before you remove the coolant reservoir cap. If you attempt to remove the cap while it is still hot, hot coolant can sputter and may cause burns.
  3. Loosen the radiator cap carefully, using a towel or thick cloth. Step back and allow the pressure to release before removing the cap completely.
  4. Add the highest quality water you can get to the radiator until it reaches the fill line. Replace the radiator cap, tighten it until it clicks and shut the bonnet of the car.

While it’s not ideal, adding water is better for your vehicle that no fluid at all.

What Type Of Water Is Best?

If you don’t have coolant available, you should top up your radiator with the highest quality water that you have. Ideally, this would be distilled water. You can also use bottled water or tap water. Bear in mind that tap water or bore water contains minerals that can leave deposits throughout your cooling system, contributing to corrosion and reducing the lifespan of the radiator.

Pros/Cons of Using Water

Using water adds contaminants to your radiator system. It’s much better for the engine to use water than to drive with low coolant, but you should replace the water with the correct coolant for your vehicle as soon as possible.

When you add water to the radiator, you dilute any coolant that may still be in the radiator. Coolant has several important functions: preventing corrosion, increasing the boiling point of the water, and lowering the freezing point of water. While you can drive the car for a short time using water in place of the coolant, it won’t effectively protect your engine.

This means its essential to get the problem that caused a low coolant level fixed as soon as possible, and the radiator filled with a 50/50 ratio of coolant to water.

When Can I Add Coolant To The Radiator Again?

car radiator coolant

Have your radiator checked over by a technician to determine why the coolant was low in the first place. The technician will locate and repair any leaks, replace any compromised parts of the cooling system and flush the radiator before replacing the coolant.

Flushing the radiator is essential before coolant is topped up again. Failure to regularly flush the radiator is one reason why aluminium radiators can fail. Make sure that your technician does a complete radiator flush after the cooling system has been repaired.

Once the radiator has been thoroughly flushed you should fill it with a 50/50 mixture of the coolant specified by your vehicle manufacturer and distilled water.

If you get into a tricky situation where you have to drive your car using water as the coolant, make sure that you get the vehicle to a radiator technician and determine the cause of the coolant loss.

Repairing the radiator as soon as possible will reduce the likelihood of potential extensive damage to the radiator, heater and engine.

A Natrad technician can diagnose a radiator problem, repair and flush your radiator. We stock the highest quality coolant and will refill your vehicle with the manufacturer recommended coolant to ensure your vehicle runs smoothly.

Ask at Natrad for radiator repairstop-up coolant or a cooling system flush