Motorcycle coolant care: check and replace

On a liquid-cooled bike the coolant keeps the engine at the right temperature and protects it from corrosion. A quick check every so often can prevent expensive damage.

Does your bike use coolant?

Many modern bikes are liquid-cooled, with a radiator and a coolant reservoir. Air-cooled and oil-cooled bikes have no coolant to check. The owner’s manual tells you which you have.

Checking the level

Check when the engine is cold and the bike is upright, using the reservoir marks (MIN and MAX).
Never open the radiator cap on a hot engine, because the system is under pressure and the coolant can scald.
If the level is low, top up with the type of coolant specified in the manual, and ask why it dropped.

The right coolant

Use the coolant type and mix ratio the manufacturer specifies. Do not mix different types unless the manual allows it.
Coolant protects against freezing and corrosion, so plain water is only a short-term emergency measure.

Look for warning signs

Drops of coolant under the bike, or a sweet smell after a ride.
Cracks, swelling or wet spots on the hoses and clamps.
A temperature gauge or warning light that climbs, or the fan running much more than usual.
Coolant that looks rusty, oily or has particles in it.

Replacement

Coolant wears out over time. Replace it at the interval in the owner’s manual, usually measured in years as well as distance. If you are not comfortable doing it yourself, ask a mechanic, and dispose of old coolant properly because it is toxic.

If the engine overheats while riding, stop in a safe place and let it cool before you check anything. Do not ride on.