Seizef piston in 1936 Johnson 100

[Tubs]

There is 2 kinds of stuck. Old dried up gas
and oil stuck and rusty stuck. Dried up gas
and oil stuck, once its broke free, is not difficult
to remove the piston. Rusty stuck you pull apart
for parts. Connecting rod and possibly the piston.
Here is one way to remove a rusty stuck.
Tubs

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

• This reply was modified 4 years, 3 months ago by Tubs.

[need2fish]

I have a mix of model 100 and J-xx; they both have (close to) the same crankcase and jug.

In all cases but one, the cast iron rings were rusted to the bore. Multiple recurring applications of solvent (CLR and WD-40/PB Blaster) and heat have worked for me.

Heat the jug slowly. Once you have it unseized, dismantle the crankcase (you may need heat etc for the bolts), clean all components and then hone the bore. Try to get the ring groove clean without removing the ring.

The one case I failed, it was because I was trying to treat a seized piston when in fact I had a seized driveshaft/lower unit — so maybe you need to check that first.

[jcrigan]

You could use the grease gun trick the break the piston free. The piston must be near the top of the cylinder to do this. Make an adapter out of an old spark plug and a zerk fitting.

[fifty20ne]

I was able to use the grease gun method to free my stuck Johnson Model 100
Has good compression now.

[Herman Powers]

Thanks I will give it a try

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