Quote:
Originally Posted by RLS7201
Holes in pistons are usually caused by detonation, from advanced timing or lean fuel mixture. Pretty hard to have advanced timing on one cylinder. The cause should have been determined before the repaired engine was started. I suspect a defective fuel injector. Have your fuel injectors flow tested to see if one of them is not delivering the proper amount of fuel. Seeing how the intake manifold gasket was replaced during the first repair, I doubt that it's the problem. Richard
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Can't speak for Ford, but GM medium duty trucks in the 90's with the big block tall deck engine had a huge problem with this very issue. Typically it was a hole in the piston from the problem cylinder firing at the wrong time. This happened because the powdered metal distributor reluctor had cracked and actually turned out of place on the distributor shaft. Since most of these older engines had throttle body injection (not port), the fuel mixture never was equal between cylinders. Once the lean cylinder fired a little bit off time, and under heavy load the piston top was destroyed.
Another issue was cross fire in the distributor cap, from corrosion which caused the wrong cylinder to get spark, (out of time) Similar technology at that time. .