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1981 Johnson 115hp Motor Rebuild Stuck at a point

C

Charles Stuckey

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" It's me again...

as b

" It's me again...

as before mentioned, we are rebuilding a 81 Johnson 115 hp motor. We have gotten the flywheel off, the stator off, all the wirs and coils and stuff. We are at a point where we are unclear on how to remove the upper crankcase head. In the diagram we have in this book, it appears that it is threaded. Could anyone please let me know what it takes to remove this part? Thanks. "
 
"Charles....The upper crankcas

"Charles....The upper crankcase head is simply held to the crankcase by the bolts that are screwed through it. However, DO NOT REMOVE the upper or lower crankcase head until you have split the block which reveals the crankshaft, rods, etc. You will need to have the upper and lower c/c heads in place to retain the crankshaft while you remove the pistons. With the c/c heads removed, it will be impossible to properly move the con rods to their positions to remove the rod caps, etc.

Joe"
 
" One more question...

What

" One more question...

What are the four allen head bolts, that are inside the crankcase. Do they have to be removed to seperate the crankcase from the power heads? "
 
"Charles.... Yes, those and th

"Charles.... Yes, those and the other large bolts are the main retaining bolts. I may have some parts left in stock for that engine.

Joe
"
 
" also...

the reason we are

" also...

the reason we are rebuilding the engine is because in the lower right cylinder, a ring peeled, headgasket was in ok condition, but sign of water mixing in cylinder. What would be a possible reason for water getting into the cylinder with a head gasket being in good shape. Cylinder walls were ok. Outer perimeter of the head (over that piston) was slightly damaged and the top of the piston was damaged. "
 
"Charles.... Water can enter a

"Charles.... Water can enter a cylinder via a damaged head gastet, a improperly torqued head gasket, a failing inner exhaust baffle plate or its gaskets (the large plate you see between the cyl heads). Water can also find its way into a bottom cylinder due to a problem with the adapter plate and/or its gaskets (the plate the powerhead sits on. Note.... Having a piston ring grab a port and causing piston damage would certainly cause enough cylinder wall damage to necessitate boring of that cylinder. I'd suggest you take a closer look at it. Also, if you don't have a servive manual for that engine, get one. It will save you from making an expensive mistake.

Joe
"
 
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