Can You Put Water In An ATV Radiator? (Mistakes to avoid)


Nothing wreaks your trail riding fun like an overheating ATV, and without spare coolant, it’s a real worry.

You may put water in an ATV radiator as a short term measure. However, water doesn’t contain anti-freezing, anti-corrosion or cooling agents and so long term use risks the health of your ATV engine.

In this post you’ll learn why straight water in your ATV radiator can cause some real damage, you’ll learn how to check coolant condition.

Coolant System

Your coolant system is very important for keeping your motor cool. Without it, your engine would simply grande.

The components of a regular coolant system include:

  • Radiator – transfers coolant heat to atmosphere
  • Rad cap – regulates the pressure of the system
  • Expansion tank – coolant reservoir
  • Water pump – moves the coolant around the system
  • Thermostat – helps warm the engine quickly
  • Thermoswitch – senses temperature and turns on fan
  • Temp sensor – senses coolant temperature and sends info temp gauge
  • Temp gauge – shows the temperature of coolant
  • Radiator fan – electric fan used to help cool the system
  • Engine jackets – coolant passage ways throughout the engine
  • Frost plugs – plugs installed in the engine wall that help prevent frost damage
  • Coolant – coolant/antifreeze liquid used to protect from frost and heat

The whole system is a sealed pressurized system, and your radiator cap helps regulate the pressure. A pressurized system is a real advantage, because is raises the boiling point of the fluid.

Straight Water Damage

You already know you can use water in your coolant system if your really stuck. But leaving it there long term causes some real problems.

Boiling your engine risks damaging the cylinder head, block and blowing head gaskets radiators etc.

Allowing your coolant freeze can cause some expensive problems too. Cracked engine blocks, cylinder heads, busted radiators are all at risks.

Coolant/antifreeze is a specially formulated to have high boiling point a low freezing point.

But your coolant does so much more that that, it contains lubricates that help protect your water pump and thermostat and seals.

Coolant also helps prevent corrosion inside your engine. Water in a coolant system long term would simply corrode these components and the inside of your engine.

Coolant Condition

Coolant should be changed at least every three years. If it’s been longer or your ATV has been running water, I would do a complete back system flush
replace the thermostat and fill with fresh coolant.

Old coolant loses it ability to protect but it also turns acidic, and tahts a silent killer.

Acid coolant will happily eat the inside of your system, rubber, plastic and your engine too.

So having coolant is important, but having fresh coolant is just as important. Changing every 2-3 years will prevent any risk of acid damage.

Checking Coolant

You can check coolant strength using a refractometer or dip strips and that will tell you how strong the mix is, very useful info.

You can also check the acidity of the coolant using a simple DVOM (Digital Volt Ohm Meter). The acidity carries a voltage charge which we can measure.

Set your meter to 5 volts dc and place the black probe on chassis ground and the positive probe tip into the coolant. A reading close to 1 indicates you need a flush and a change of fluid.

John Cunningham

John Cunningham is an certified mechanic and writer on I’ve been a mechanic for over twenty years, I use my knowledge and experience to write articles that help fellow gear-heads with all aspects of ATV ownership, from maintenance, repair to troubleshooting.

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