At higher mileage services, Harley coolant needs to be replaced.
To drain the cooling system, start by removing the motorcycle’s main fuse and remove the access panel from the lower, right side fairing. Remove the reservoir rubber fill plug and the pump cover. Remove the hoses from the pump but be carefull, the hose barbs on the pump are fragile. Especially the plastic, left side barb. Drain and discard the used Harley coolant.
When re-connecting the hose to the pump, make sure that the hose clamp is installed between the raised barb and the pump body. It is important to avoid installing the clamp directly over the raised area. Connect the hose to the pump and secure with clamp. The hose is only installed correctly when the end of the hose is touching the pump housing. Finnish up by re-installing the pump cover and the main fuse.
There are two ways that the Harley coolant can be replenished: Power fill and bleed or Manual fill and bleed. The power fill and bleed procedure requires the use of a specialty tool and an adapter. The manual fill and bleed will be the more common technique for riders to complete at home.
With the motorcycle upright and level, pull the filler neck from the retainer on the Harley coolant bottle and remove the pressure cap. Fill the system through the filler neck until coolant becomes visible. You may need to pause for a few seconds and wait for the coolant to bleed down.
To bleed the cooling system, turn ignition switch and run switch to ON but do not start the motorcycle. Turn the throttle to greater than 50% and hold for, at least, three seconds. The coolant pump and fans will begin to run. The system is now in bleed mode. You can release the throttle. With the pump running, continue to add Harley coolant until the system is completely topped off. Turning off the ignition switch will stop the pump and fan from operating. Install the pressure cap and return the filler neck to its retainer on the coolant bottle. Fill the coolant bottle to the full cold line and install the rubber fill plug.
Finally, start and run the motorcycle until normal operating temperature is reached and check for leaks.