Earlier this summer I purchased a fishing boat with a '78 Merc 402 (2 cyl 2 stroke). Long story short a previous owner overheated the motor (water pump) to the point that the pistons/bores are scored & compression is poor (115/100). I picked up a used power head with good compression (150/150) and I plan on swapping them out. I have a few questions I'd like to ask...
1) Before installing the replacement power head I plan to replace a few gaskets; cylinder cover, exhaust manifold, carb kit, etc. Should I consider replacing the top & bottom crankshaft seal? Noticed a little oil under the trigger assembly but no signs of a gusher. Nothing noteworthy on the bottom side. Any other recommended gaskets?
2) The replacement came with a stator attached, but the insulation on the wires is crumbling. I have a service manual that covers many models that gives resistance specs for the ignition windings but not for the battery charging windings (2 yellow wires). I hooked my multimeter across the yellow wires & got a reading of 2 ohms - seems low. Before I go to the trouble of repairing the wires, would anyone have the resistance value for these charging coils?
3) On the stab side of the motor, forward of the fuel pump but aft of the starter, is a small diameter hose that runs vertically from the top main bearing area to the bottom; maybe it is a drain or perhaps a balance tube. Just wondering what it is & what purpose it serves.
Appreciate the help,
Joe in St Louis
1) Before installing the replacement power head I plan to replace a few gaskets; cylinder cover, exhaust manifold, carb kit, etc. Should I consider replacing the top & bottom crankshaft seal? Noticed a little oil under the trigger assembly but no signs of a gusher. Nothing noteworthy on the bottom side. Any other recommended gaskets?
2) The replacement came with a stator attached, but the insulation on the wires is crumbling. I have a service manual that covers many models that gives resistance specs for the ignition windings but not for the battery charging windings (2 yellow wires). I hooked my multimeter across the yellow wires & got a reading of 2 ohms - seems low. Before I go to the trouble of repairing the wires, would anyone have the resistance value for these charging coils?
3) On the stab side of the motor, forward of the fuel pump but aft of the starter, is a small diameter hose that runs vertically from the top main bearing area to the bottom; maybe it is a drain or perhaps a balance tube. Just wondering what it is & what purpose it serves.
Appreciate the help,
Joe in St Louis
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