I took out the thermostat. On the way home the engine started to knock . I was almost home and it didn't sound like a rod knock it wasn't that loud. I took off the rocker cover and the number 4 cylinder exhaust valve was stuck open. I don't know what's next but I think it involves the machine shop that rebuilt my head. I'm not sure what I can except from the machine shop but I hope they will help. Chuck 49
