0404171937-00 by TexasJohn55 posted Apr 21, 2017 at 11:09 AM For all those who have ever tried to unstick a frozen heat riser butterfly valve. It is nearly impossible to get penetrant down into the shaft bore. I drilled small holes in the flange face to the shaft. After soaking for a day with PB Baster it finally freed up by tapping shaft back and forth. With manifold on bench and flange face up, use a syringe to inject the holes every few hours to keep it saturated.
That's a good tip that could be used even with the manifold on the engine, in the car. It would just be a bit messier drilling and spraying penetrant upside down.
