Pressurized vs. regular radiator overflow

[Efi69Cam]

Has anyone considered using a pressurized overflow tank on a LS swap? I was considering using the same arrangement as a late GM truck. I've seen tanks in boneyard cars that look like they'd fit.

Does anyone know if there is a benefit to this? The only real change would be that the radiator cap on the radiator would have to be eliminated.

[GregWeld]

Most all of my overflow tanks are threaded and O'ringed. Not sure it makes much difference as long as there is about 2/3rds of the overflow tank full when cold. What you don't want is AIR coming back into the system when the engine etc is cooling off. Ask me how I know....

[dontlifttoshift]

Two different things.

Overflow or recovery tank just catches what comes out of the radiator when the cap purges pressure and hopefully puts it back when the coolant returns to normal temperature. An overflow tank is not sealed, it is open to the atmosphere.

A pressurized tank link in all late models, also know as a surge tank, degas bottle, or expansion tank is different in that it is part of the sealed system. The fill line in the degas bottle must be higher than the radiator or it will not work properly.

A degas bottle can be used in conjunction with an overflow tank but most OEMs have engineered enough air space into their tanks that it will never push fluid out of the cap.

[Efi69Cam]

Gotcha on the terminology. What I'm looking to do is convert to a surge tank with the pressure cap on it rather than the typical overflow tank.

Based on observation over years of maintaining cars with the surge tanks, it seems the coolant lasts longer, maybe exposure to air is a problem?