Mercury kd3s

[collinh19]

So my mercury is seized(been sitting for 30 years) I’ve gotten it this far. Any tips on how to get the piston out of the cylinder head. It’s currently soaking in ATF and Acetone. I would really like to get this motor back in working order.
Thanks

[garry-in-michigan]

Close off he ports by bolting on a heavy well sealed steel plate. The bypass ports are a problem. Since iron is tougher than epoxy, you might use epoxy to get a good seal. Then make an adaptor to screw into the spark plug hole and screw a grease fitting into it. Fill the cylinder with penetrating oil followed with high pressure grease. A grease gun can develop over a thousand pounds of pressure. Depending on how rusty the iron is, you might re-enforce the cylinder with a row of Aircraft style hose clamps. A little heat around the base of the cylinder shouldn’t hurt.

[green-thumbs]

You can use four threaded rods at the point you are at to jack the cylinder off the piston.
When the cylinder is as far from the crankcase as in photo the piston may be
below the ports or close to it so grease gun is not likely to gain much.
I assume the piston has already been unlocked and moved down the cylinder and also
that crankshaft and rod are not frozen.
Do NOT use a metal rod to pound on piston thru spark plug opening…a wood dowel
may sometimes work if piston is not sticking…threaded rods work better slower if piston is stubborn.
Be generous in use of lube and penetrating rust solvents…makes a mess to clean up
but may ease piston out of cylinder.
Love the little Mercs
Louis

There is a sequence of photos at Jason Baxter Wizard site showing use of threaded rod and nut/washer set up to remove a stuck piston that was still stubborn after use of grease gun.
Note: the threaded rods pull against the connecting rod…as long as the piston moves
it should not be a problem…if piston refuses to move something may break or distort.

There seems to be no lack of stuck early Mercury, Wizard and Sea King single (Kiekhaefer)
and even more abundant are stripped, broken and messed with examples. Fear not, the
modular design and shared parts make it possible to replace defective or missing mechanical items to make a runner if not a blue ribbon winner.
Louis.

[collinh19]

Thank you I will try that. If it.turns out to be damaged beyond repair, are parts or a powerhead hard to come by?

[Anonymous]

Here is Mr Tubbs’ video on stuck pistons.

https://www.youtube.com/watch?v=QcAwNp0mzRs

Good luck.

Steve A W

[green-thumbs]

When the powerhead unstuck tell us how and what you found within.
Photos Please. The Rest of the Story if you will.
Louis

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