Coolant in my '13 wr 450

My expansion tank is empty but my radiator is full so I was just going to top off the expansion tank and realized that it has blue coolant. Is this yamahas way of making me pay inflated dealer prices for coolant that is dyed blue instead of the green coolant I have sitting in my garage. Or is it actually a special coolant?

Not 'special' but it is made for aluminum engines with an aluminum radiator. Just be sure it is designed for your engine.

What do you hope to achieve by adding more radiator coolant that is needed?

I would always have small amount in the overflow tank so you can see it.Not have to take off cap,to check on long rides.BTR

What is there to check?

That is what the overflow tank is for.

It's a sealed system, no coolant can escape.

Besides, if you are overheating, you have other problems in jetting or exhaust.

It works exactly the same as the overflow tank in your car. I guess a better name for it is degas bottle. It's purpose is to keep air out of your cooling system. If air is present you will get corrosion. How it works is as your cooling system heats up the coolant expands building pressure. As we all know you cannot compress a liquid so the expanding coolant has to go somewhere. As the pressure reaches the the pressure rating of the radiator cap it pushes coolant past the cap through the hose and into the degas bottle(overflow). As it does this it will also purge any gas (air) out of the system which is what you want. Now your ride is over and you shut the engine off. The engine and coolant begin to cool off, and as the coolant cools off it contracts back to its original state. As it contracts it actually pulls a vacuum inside the cooling system, which overcomes the valve on the radiator cap and draws coolant out of the degas bottle and back into the radiator. This keeps the cooling system completely full and purged of air. If all the degas bottle was there for was overflow there's not a chance Yamaha would put it on the bike. They would just put a hose on the radiator and direct it to the ground the same as they do on the yz's.

I think the bottle is there for environmental reasons.  The YZ450, with an almost identical engine/cooling system, does not have the bottle because it's made for closed course competition only.  I guess it's OK to spill glycol on private property....

Simple answer to why I like small amount in overflow tank that I can see.When doing rides,its my job to make sure all the bikes,are working.So on a 4-5 day ride.When we take a break,if I can see all the bikes have small amount in overflow tank.Then I know,rad hose does not have pin hole from brush,or rad.Where talking riding heavy brush,also looking over 4-9 wrs on ride.BTR

Yes, put the proper coolant into the tank and fill it to the fill line noted on the tank itself and ride :thumbsup:


You will notice that you don't have any coolant in the line that runs from the tank to the radiators.

Edited by KennyMc

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