Mark sliced off the bottom of Pachuca's faulty muffler and the accompanying photo reveals what we found. Exhaust heat entering from the side port melted the exit tube causing a severe crimp. Mark says that the back pressure to the cylinders would have been "off the scale" and it is a wonder that the engine ran at all. The PM confirmed Mark's suspicion that the innards of the muffler were made of ordinary PVC plastic and that the entire thing had been encased in fiberglass.
The other photo shows the new muffler next to the old one. The new muffler was fabricated entirely with heat resistant material.
Nancy Erley developed a severe back pressure problem on her SABB 2G that resulted in a cracked piston in one of the South Pacific islands - Tonga, I think - during one of her two circumnavigations. I was very to not have suffered the same fate. (Nancy managed to get the parts for an engine rebuild from the cylinder sleeves on up.)
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