How to rebuild an Air cooled VW motor?

How do you fix a sticking exhaust valve in a VW 1600 air-cooled motor?

• Answer:

  If the exhaust valve is on the #3 cylinder (driver's side, frontmost cylinder), it is the one that gets the hottest in the aircooled VWs. It is also the one that is most likely to burn or get 'swallowed' (broken off and being rammed by piston). Usually sticking is caused by the valve guide being worn, so pulling the head is mandatory. Assuming it's really stuck open and not burned, here's something to try. Put the offending cylinder at Bottom Dead Center (farthest away from the valves), remove the valve cover and tap the stem of the valve with a plastic or brass hammer, or piece of wood between a regular hammer and the valve stem/spring retainer. It may pop back up. Turn the engine over by hand to see if it sticks again.