The Stovebolt Site Forums The Shop Area Engine Shop Stuck heat riser in exhaust manifold

Kroil or PB Blaster are both good penetrants. My best luck with freeing the stuck riser is using acetylene to heat the manifold until it's red. You need to be gentle with everything, it's easy to twist the shaft or shear the pin through the balance weight. If it's to tough you might have to drill out the rivets through the flap then drive the shaft out. A mixture of graphite and linseed oil is the lubricant of choice to keep it from seizing again.