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filling the RV-12iS coolant system

Major-Tom

Active Member
I hope this doesnt sound to stupid, but I wonder how to fill the coolant system in my RV-12 iS. I have the built manual and the maintanance manual. It reads kind of "just fill it". But would that not trap air in the radiator, since both inlet and outlet are on the bottom side? Then there is the radiator plug. A good place to remove the trapped air. But the built manual reads install the plug using pipe thread sealant. So I think the plugs stays in. What am I missing?
 
Page G4-1 of the PAP tells you to fill the radiator to the bottom of the radiator plug before torquing and safety wiring in place. I had to call Van’s to ask why I wasn’t filling the remainder of the coolant hose up to the expansion tank. The answer was that we’re supposed to do just that after filling the radiator. They also suggested lowering the tail of the plane after the first fill in the expansion tank to work any bubbles up to the tank, then top off if the level dropped.
 
It also helps to do a few brief runs after filling and checking for air in the header tank on top of the engine and refilling after each run if needed. We used to perform pump sweeps in water cooling systems in power plants to move air to the high point for venting after a fill.
 
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