How to Change Motorcycle Coolant

We change the oil and the brake pads, check the battery, and clean or change the air filter as part of a regular maintenance routine. But what about the coolant?

It's an often overlooked, yet very simple maintenance task to change out the coolant on a motorcycle. Aluminum components corrode over time as the coolant breaks down, which is why most manufacturers recommend replacing your coolant every two years or 24,000 miles. Watch the video above and follow the steps below to learn how to change the coolant in a Honda motorcycle.

NOTE: We changed the coolant on a Honda VTX 1800 motorcycle, but the steps for changing the coolant are the same or similar for most motorcycles.

Honda motorcycle coolant change how-to

Tools and Supplies - Motorcycle Coolant Change 

  • 5mm, 6mm Allen
  • 3/8th ratchet and extensions
  • 10mm socket
  • 10mm wrench

Buy Honda HP coolant

Buy auxiliary fuel tank

NOTE: You need to access the fill cap on your motorcycle, and on the Honda VTX 1800 that means removing the seat and the fuel tank.

Removing the Fuel Tank

Step 1. Remove the seat by locating two 6mm Allen bolts, one on each side of the seat near where the shock absorbers connect. Once those bolts are removed, the seat simply lifts off. 

Honda VTX 1800 motorcycle fuel tank removal

Step 2. Remove the fuel tank by taking the rear nut and bolt off. They're located at the base of the tank near where it meets with the seat. 

motorcycle coolant change fuel tank removal

NOTE: You may need to lift up slightly on the tank to relieve the pressure on the bolt. 

Step 3. Remove the center display of the tank by taking off the 5mm Allen bolts holding the center display on the tank. Then, remove the fuel cap so you can lift the display off the tank. Once the display is removed, you can replace the fuel cap. 

Honda motorcycle coolant change center display removal

Step 4. Drain the fuel from the tank. The VTX 1800 has two lines: one feeds the motor and one is a fuel drain line. You'll need to get to the fuel line that feeds the motor to drain the tank. First, disconnect the fuel line and then immediately connect another hose to the tank running to an auxiliary fuel tank

Honda motorcycle coolant change fuel tank drain

NOTE: Fuel will pour out during this step, so make sure there isn't anybody smoking nearby.

Step 5. Once the tank is empty, you can lift it enough to disconnect the fuel level sensor, two vent lines, and the drain hose. 

Step 6. Slide the tank back and lift it off of the machine.

Honda VTX1800 coolant replacement drain line

NOTE: Engine coolant is extremely toxic, so make sure all of the drained coolant is captured in a reservoir, and keep it away from children and pets.

Draining Honda Motorcycle Coolant

Step 1. Remove the cover on the left-hand side of the motor that protects the thermostat housing and drain bolt. It's held in place by several 5mm Allens that ring the perimeter of the cover. 

Honda VTX1800 motorcycle coolant change

Step 2. Remove the filler cap. On the Honda VTX 1800, it's located on the left side of the engine and visible once the fuel tank is removed. 

Honda motorcycle coolant replacement filler cap

Step 3. Access the drain bolt down below where the thermostat cover was just removed. Have a drain pan handy, and then loosen the bolt. The coolant will flow out of the system. 


Honda motorcycle coolant replacement drain bolt

NOTE: You don't need to remove the bolt all the way to drain the system, but if you do, make sure not to lose the crush washer on the drain bolt. 

Honda motorcycle coolant flush

Step 4. Remove the cover protecting the reservoir. It's held in place by a couple of Phillips screws.  

Honda VTX1800 motorcycle coolant reservoir

Step 5. Remove the reservoir, which is also held in place by two Phillips screws. Next, disconnect the top and bottom hoses with a pair of pliers.   

Honda motorcycle coolant change VTX 1800

Motorcycle coolant change Honda

NOTE: Before refilling the motorcycle coolant, first close off the system.

Refilling Honda Motorcycle Coolant

Step 1. Replace and remount the reservoir, reconnecting the top and bottom hoses, and replacing and tightening the Philips head screws holding the reservoir in place.

Step 2. Re-tighten the drain bolt. If you removed it completely, make sure you have the crush washer.

Step 3. Refill the reservoir with Honda HP coolant. The coolant capacity on the 2005 Honda VTX 1800 is 3.3 quarts, so begin pouring it into the opening for the fill cap. Use some coolant to top off the reservoir as well. 

Honda motorcycle engine coolant

Step 4. Run the engine. If you moved your fuel to an auxiliary fuel container, connect that tank to the fuel line on the motorcycle. Be sure to plug the fuel drain line.

Honda VTX 1800 motorcycle coolant change

PRO TIP: A bolt pushed into the drain hose that fits nice and snug makes a great plug. 

Step 5. Leave the radiator fill cap off and start the engine.

Step 6. Add more coolant as you see the fluid level inside the radiator drop. As you're running the machine, rev the engine a few times to move the coolant around. After two or three minutes, stop the engine. Finally, replace the radiator cap; the covers over the thermostat and drain bolt; the reservoir; and the fuel tank and seat.

Ready to do a Honda motorcycle oil change next? Watch the video above to see how to change the oil in a Honda VTX1800 motorcycle.


Why Partzilla?

Commercial Discounts

Special discounts for companies in the powersports industry


Government Sales

Discounts for federal and most state and municipal agencies