Coolant Change Trick

By Fred Scott
September 2000

This may well be an old trick, but I noticed that your coolant articles didn't mention it, so I thought I'd pass it along. It's a simple method for changing your coolant without ever removing the gas tank.

What you need is a fluid pump with an attached hose. You can buy these at auto parts stores for less than ten dollars, and they're designed to screw onto the mouth of standard antifreeze containers.

Unscrew the top mounting screw on your radiator so that it can swing forward about an inch. The filler cap is connected to the radiator by a short rubber hose. You can now disconnect this hose from the radiator without removing the fuel tank. So once you've mixed up your antifreeze, refill the original container with your mixture, and put the pump on the container. Use the hose on the pump to pump the fluid directly into the radiator. Pump slowly so that the fluid doesn't spill. Eventually, the radiator will be almost full, and you can reconnect the hose. Fill the reserve tank as normal.

You will have some air in your cooling system, so don't go on a long road trip right away. Take some short rides, and let the engine cool between rides. Each time it cools, fluid is sucked from the reserve tank into the system, and when it heats again, air is released from the overflow into the reserve tank, and out. So carry a small amount of coolant with you to top off your reserve. In my experience, half the capacity of the reserve tank is plenty.

I don't know if this is actually faster than taking off the tank. If you're a pro, it's undoubtedly slower. However, it's also a lot easier.