Frozen Manifold Heat Control Valve

We use a 50/50 mixture of ATF and acetone for stuff like this. It penetrates like no other and could spare you the hassle of having to remove the entire exhaust. I’d give it a thorough spray down (let it sit 24 hours), let the vehicle barely heat up (for 2 minutes or less) and then man handle it with your best pair of grabbers and or a bfh.