Still need to have your overflow canister vented to the outside air to allow expansion coolant to move freely into it, and also allows coolant to freely return to the radiator when it is cooling back down.
Right now you have a 100% pressurized system, making it hard for expanding coolant to get out, as the overflow canister is pressurized too without being vented to the outside air.
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Right now you have a 100% pressurized system, making it hard for expanding coolant to get out, as the overflow canister is pressurized too without being vented to the outside air.
☆☆☆☆☆