Perkins 4108 Overheating

[irwin_37]

Two problems which may be related
1. The engine overheated some years back on a final cruise before being hauled for a major retrofit which lasted several years. When relaunched some years later, the overheating issue was of concern and trials showed that the temp would rise gradually until the coolant vented past the filler cap pressure release. The fan belt was noted to be slipping, eventually diagnosed as a result of the alternator tensioner backing off while the engine was running. The tensioner bolt had stripped threads. Thought all was cured, but have not done much motor cruising this year.

2. For winter lay-up, we typically purge the raw water in the heat exchanger and muffler by displacing it with antifreeze, drawing it from a pail above the engine with the engine running until the pail empties and antifreeze is noted coming from the exhaust. This time around, the pail would not drain! Inspection of the water pump">raw water pump revealed a badly scored impellor. While replacing the impellor, I tried to turn the pump shaft and noted that it would not turn. (I believe this is normal?) With the pump reassembled I tried to prime the muffler and heat exchanger with antifreeze agin, but again the pail would not draw antifreeze. The pump was dismantled again and the shaft rotation determined by having a friend role the engine over with the starter motor. Pump rotation was clockwise. Tried this a second time, and the impellor would not rotate at all. Pulled the impellor and looked for shaft rotation without the impellor installed. It was intermittent. Then tried turning it by hand and noted it free wheeling then locking up. At that point, I pulled the pump to examine the drive end for damage. Found none on the pump or on the split shaft sticking out of the timing cover. That shaft could be turned by hand with no resistance in either direction. With the starter motor, the engine was turned over again noting the pump adaptor plate rotated clockwise, but the shaft at it's center did not rotate. The manual says not to remove the pump adaptor plate, since a special tool is needed for re-alignment the plate. Also some comment in another part of the manual that states the linkage is cenrifugally activated, but graphics are poor and no details found related to a clutch mechanism. Not sure if there is a clutch behind the adaptor plate, or if the pump shaft is supposed to be gear driven by the timing gear which also drives the fuel pump on the other side of the housing. If the latter, then some significant work ahead to repair.

Anyone have a similar problem before or know of a marine engine mechanic who knows for sure?

Appreciate all comments.


Thanks, rM