Turbo_Boss wrote:Hey Low Level, what oil was using in that 618? If you check one of the pic you will see the piston pin has rust.
Also that carbon deposit over the piston has a strange color
These pistons been lying in the hangar for almost a year. The engine was run on Castrol super outboard.
Stephan van Tonder wrote:Also whatever came off in the coil bits cannot end up inside the pistons. So the damage inside was caused by something else.

That I obviously know. There was no bits and pieces in the engine.
This happened with my hangar mate's T-bird while training. Unfortunately at that stage, he didn't know the plane that well, therefore didn't notice anything on engine performance. In retrospect, after the engine was fixed, he know can say, that for a while the engine wasn't producing full power. The final chapter was, when he couldn't get off the ground. The engine started easy, and revved well, the power just wasn't there.
What we think, is that the shafing on the coil happenned over a period, losing spark then and now on the cylinders respectively, one more than the other. Slowly the detonating damaged the pistons to the point where the engine just couldn't produce the goods anymore. The loss of ignition, and detonation, fortunately, never went to the extremes of an engine out.
I am still of the opinion, that foreign matter in the cylinder will cause markings all over the crown, not only on the edge of the pistons, and if so, it is strange that the same foreign matter was in both cylinders .
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