How to Replace 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. Here's how to change the coolant on a Honda motorcycle.

Tools and Parts Needed - Motorcycle Coolant Change 


  • 5mm, 6mm Allen
  • 3/8th ratchet and extensions
  • 10mm socket
  • 10mm wrench
  • Pliers
  • Phillips-head screwdriver

Motorcycle coolant change how-to

Removing the Fuel Tank from a Motorcycle

You'll need to access the fill cap on your machine, and on the Honda VTX 1800 that means removing the seat and 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. 

motorcycle fuel tank removal

Step 2. Next, start removing 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. To fully remove the bolt, you may need to lift up slightly on the tank to relieve the pressure on the bolt. 

motorcycle coolant change fuel tank removal

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. 

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. Fuel will pour out, so make sure there isn't anybody smoking nearby! First, disconnect the fuel line and then immediately connect another hose to the tank running to an auxiliary fuel tank

motorcycle fuel tank drain

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. 

motorcycle coolant replacement drain line

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

Draining Motorcycle Coolant

NOTE: The first thing to remember about engine coolant is that it's extremely toxic! Make sure all of the drained coolant is captured in a reservoir, and keep it away from children and pets.

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. 

motorcycle coolant replacement

Step 2. Remove the filler cap. On the Honda VTX, 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. Down below where the thermostat cover was just removed, you'll access the drain bolt. Remember to have a drain pan handy, and then loosen the bolt. The coolant will start to flow out of the system. 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 replacement

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

motorcycle coolant removal 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 removal

motorcycle coolant drain

Refilling with New Coolant

The process to refill the motorcycle coolant is simple. First, close off the system.

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. Begin refilling it with Honda motorcycle engine 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 you plug the fuel drain line.

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

auxiliary fuel container motorcycle coolant replacement

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. Again, this machine takes 3.3 quarts. 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.


Now that you know how to change out the coolant on a Honda VTX 1800 motorcycle, why stop there? Watch the video below and change the oil on your Honda motorcycle while you're at it!



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