Reply To: Mercury KD4

[green-thumbs]

Several things I would want to know if it was on my agenda.
1) are rods rusted to crankshaft
2) are both pistons stuck
3) signs of prior attempts to unstick

I have had good results with Marvel Mystery Oil on very lightly stuck
powerhed. If both pistons are stuck and or rod bearings rusted to
crankshaft. freeing up and disassemby may be difficult,

I would apply oil thru spark plug opening, exhaust ports and thru crankcase opeing to cylinders. The stuff oiled paper in thru spark plug opening to reduce volume of grease required. Next attach grease gun to spark plug adapter and attempt to free piston that is hight in cylinder,
Do not overdo it! Exhaust ports can be blanked off to seal grease in
If you can move piston down far enough to gain work space between
cylinder and crankcase for nuts and threade rods you can pull the
piston completely clear of cylinder. The piston often will require this
to mover it the last inch or two our to cylinder.
Both grease gun and nuts, washers and threaded rods are powerful
tools that will free up most stuck pistons and ALSO break things if nothing wants to give.

I once pickup up a stuck KE4 powerhead that someone had tried to freeup with a pipe wrench. Did not work and lefte deep indentations
on crankshaft taper. It responded to greasegun methods with very
little pressure. needed.

Sometimes you can remove unstuck cylinder and piston & rod assembly and gain enough space between the stuck cylinder and crankcase
to use nuts, washers threaded rods to pull the piston out. Depends
on where piston is in the cylinder.
If low a go, If high grease gun.
Louis