One cylinder-low compression

[RangerBob]

daselbee was right about my 1995 Johnson 130hp. One cylinder has about 30psi while the others are around 120-125. I fear I have toasted the piston. Does anyone know the cost to replace the piston? I am fairly mechanically inclined so I know I could replace a piston but is there anything I should be aware of? Will I have to get the cylinder bored? How much cash am I looking at?
Mark

 

[bktheking]

Re: One cylinder-low compression

To do it right - all 4 sets of rings, a piston , gasket set, possibly a full carb rebuild, possibly stats, maybe bearings maybe a overbore or sleave job- possibly a g note- it's a crap shoot.

 

[emdsapmgr]

Re: One cylinder-low compression

You will need to know what caused the failure. Running lean or an overheat. You don't want to reassemble till you know it will run without the same problem recurring. Pull the carb apart and inspect the jets that fed the bad cylinder.

 

[kenmyfam]

Re: One cylinder-low compression

Agree, you must root cause it or it could happen again very quickly after all the re-building efforts.

 

[jonesg]

Re: One cylinder-low compression

daselbee was right about my 1995 Johnson 130hp. One cylinder has about 30psi while the others are around 120-125. I fear I have toasted the piston. Does anyone know the cost to replace the piston? I am fairly mechanically inclined so I know I could replace a piston but is there anything I should be aware of? Will I have to get the cylinder bored? How much cash am I looking at?
Mark

Pull the head , you're too far ahead of yourself, could be a blown gasket, warped head.

DIY you can re-ring all 4 and re-hole 1 for around $600.
I'd do them all while you're in there.