CM 871 Burnt Valve

[Rawze]

A burnt intake valve could be ...

Head is completely worn out and valves are riding too hgih in their seats. Valve finally gave way due to not enough meat to seal it properly.
ref with pics.: http://rawze.com/forums/showthread.php?t...66#pid9466

Could be chunk of hardened carbon, or some other foreign material (metal frag from a turbine of previously failed turbo, etc.) made its way into the valve seat and cracked the valve,.. eventually resulting in a burnt valve.

Could also be from the sudden inrush of -20 degree-C temps (dead of winter) at the top of a mountain, engine under full load, cylinders already very hot, jake brake set to 0 delay + it set on high, engine transitioning form full throttle to full engine brake too quickly in extreme conditions, cracking/weakening the valve, then eventually it burning through several months later.

Just some generalized guessing there.