PUMP & COOLANT
Keep your machine running
cool in the heat
By the staff of Dirt Wheels
❏ Routine maintenance is key to keeping your machine
on the trails or track longer with less downtime for repairs.
The cooling system can often be overlooked at times, but in
reality it needs just as much attention as the other moving
parts. Without the cooling system working properly, you
can experience many different mechanical failures, such
as overheating, burst hoses or coolant leaks. For this
“How-To” we show you how to replace the radiator hoses,
water pump impeller and coolant on a 2008 Yamaha
YFZ450, but the steps apply to any liquid-cooled machine.
We contacted Boyesen for its SuperCooler kit, along with
tough silicone radiator hoses from CV4. We also chose
to upgrade the cooling system with an Evans waterless
coolant. Evans coolant aids cooling, but most important,
it does not boil out of the overflow like a conventional
coolant. That helps maintain the coolant volume in tough
To drain the coolant system you will find the drain
plug located on the water-pump cover. This 8mm bolt is
removed, allowing the system to drain in a pan. You can
remove the radiator cap to relieve pressure for a faster
drain. You need to take care at this point to keep the
coolant contained. You don’t want to spill the coolant.
With the system drained you can begin to remove the
radiator hoses. Most hoses are held in place with spring
clamps, and a good set of pliers will help remove these
clamps with ease. Some hoses may have worm-drive
clamps that require a screwdriver.
Remove the remaining bolts holding the water pump
cover. Be careful to not damage the O-ring as you remove
the cover. You will need to reuse the O-ring on the new
cover. Buying a new O-ring before you start might save
headaches later, and they are not expensive.