wouldn't the way to stop having cooling system pressure in the heater core be to shut off both hoses? wink

either hose is part of the same closed system, which makes it worth considering the integrity of the core when choosing a rad pressure cap

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot