Cheap Guy
Active Member
I have a 1989 Sundancer, with the 260 and Alpha 1 Gen 1. Last year my drive locked up and apparently shot the porcelain from the rear most starboard cylinder out of the seat of the plug. The threads were still good. Normally I do my own work but due to health issues I had a mechanic replace the stern drive and the plugs but the engine still wasn't running right. Fast forward to today. I had the stern drive replaced by another mechanic and I checked out the plugs and rotors myself. The mechanic used Champion RV91MC. I replaced them all with AC Delco MR43T. Two of the Champion plugs had smashed electrodes as shown in the picture. After replacing the plugs, the engine is back to running smooth like it used to, as would be expected. My question is what could have caused the electrodes to be smashed in like shown? One one on the starboard side as stated, the other was on the port side, second from front.