Combine radiator expansion tank

[Mr Charisma]

Good morning you clever lot

During the day my combine fills the expansion tank to full but does not pull it back into the radiator as it cools,,,,,,, before we start ripping it apart is there something simple we have overlooked

 

[davidroberts30]

Radiator over full?

 

[Mr Charisma]

Radiator over full?

Just above the fins

 

[davidroberts30]

Just above the fins

Does it stay there or does it get less the second day

 

[Courier]

Try replacing the pipe between the radiator and the expansion tank - Sometimes the pipe lining can de-laminate and act as a one way valve.....

 

[Exfarmer]

as Op says, could be seal on pressure cap, The air must also have a way of getting back in the expansion as well, could be blocked

 

[Courier]

as Op says, could be seal on pressure cap, The air must also have a way of getting back in the expansion as well, could be blocked

Agreed, the rubber seal on the pressure cap can go sticky with age....

 

[Wisconsonian]

The radiator cap inner rubber holds the pressure inside the radiator. The outer rubber seal holds the vacuum to pull the coolant back into the radiator. The little brass washer in the middle is the check valve to let the coolant back in, so that can stick to the seal like Courier said, or the outer rubber seal can be cracked enough to let air back in so it won't suck the coolant up. Inspect those places, or get a new cap. If that doesn't fix it, then pressure test the cooling system. Don't take anything apart without a plan. The radiator should be full to the point of dripping off the cap when you open it if there is a working expansion tank.

 

[ACEngineering]

Good morning you clever lot

During the day my combine fills the expansion tank to full but does not pull it back into the radiator as it cools,,,,,,, before we start ripping it apart is there something simple we have overlooked

as @Wisconsonian said, Rad cap, either stuck inner valve or someone fitted the wrong type of cap.

 

[Mr Charisma]

Thank you all , original cap rubber had disintegrated , took some time to find a replacement but that hasn't cured the problem , might still be a wrong cap if course , will try a new pipe between rad and expansion tank

 

[kevindb880]

Good morning you clever lot

During the day my combine fills the expansion tank to full but does not pull it back into the radiator as it cools,,,,,,, before we start ripping it apart is there something simple we have overlooked

You combining already?

 

[B'o'B]

You combining already?

He’s a good Boy Scout!