I'd had overheating that would happen only sometimes, always right away, and would go away if you shut down and restarted a time or two.<br /><br />I pulled the lower end's water pump, and it was a bit chewed up, primarily at the top of the pump housing, around the drive shaft. I believe this (Sierra) unit was defective, with the inner can improperly drilled, so it rubbed against the shaft. The heat from this melted part of the plastic housing, as well as a small part of the impeller. It also melted and deformed the can itself slightly, and some can-metal welded itself onto the shaft (I had to remove that metal from the shaft to get the impeller off). Anyway, I just put a new complete water pump in there, including the base. It worked fine on the hose, and just fine as well in a trip on the water. So my sense is that I've licked this one.<br /><br />Thanks! And watch this space for an ignition coil question! :-(
