Review on 🔧 Improved Radiator Vent Valve by GM Genuine Parts - 13267637 by Matt Larsen

I don't like that it's plastic because when it gets hot and you try to bleed the system by unscrewing the valve the plastic tends to soften. Too many attempts to unscrew the valve will result in the breather head breaking off or, if it cools but does not cool completely, the breather head will break. Most importantly, do not overtighten the exhaust valve. You may need to loosen the valve to remove any air bubbles from the radiator. The rest fits fine. I prefer to use a 12mm socket to loosen the valve and use a fat Phillips Phillips screwdriver to tighten it just enough that you don't see a coolant leak.