i have a 10 year old fh580 that keeps bending push rods due to sticking valves. happened twice this season , first on the exhaust valve ,then the intake on the same cylinder. what causes sticking valves ? i'm assuming fuel grade might have a factor . is it time for new heads and valves ??
Carbon buildup in valve stems due to wear, seal failure, repeated shutdown at high engine temperature (oil at +280F). If mechanical valve adjustment : no lash or negative lash (clearance).
