by bgsengine » Mon Aug 11, 2014 2:31 pm
Most common is overheating - valve guide slips out of place, valve rocker bottoms on guide and bends pushrod
Other possibility is failed hydraulic lifter that pumped up and would not self adjust, or some object between exhaust valve and piston jamming valve from moving or a frozen or stuck valve.
How poor are they who have not patience. What wound did ever heal, but by degrees? - Iago (Othello Act II, Scene 3)