1990 Volvo 740 4 cyl. Hole burned through top of piston 4. What is the cause? on 1990 Volvo 740

I pulled the head and there is a hole burned through the top edge of the piston.

by in Whitehall, MT on August 09, 2012
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1 answer
ANSWER by , August 09, 2012
either something poked a hole or it ran so lean it burned a hole. lean could have been from a number of things