scuffed cylinder question

[dsujen]

I have a 1987 90hp johnson J90tlcur. Was breaking up at full throttle on the river. Took it to a marine mechanic for a tune up. He said cylinder 3 is 90 psi and there is aluminum transfer to the cylinder wall and the piston is scuffed. Is there any easy way to fix this without a total rebuild? He told me if I kept using it the way it is, it will seize up at full throttle soon.

 

[littlerayray]

No easy fix need to reborn the cylinders as far as I'm concerned

 

[racerone]

Very common failure on these motors.---Motor needs to be torn down for proper repairs .---Cause of the failure must be deternined otherwise it will fail again !!

 

[emdsapmgr]

Important to find out why the cyl liner scuffed prior to deciding to rebuild. Maybe a restricted main jet on that side of the carb. Causing that cyl to run lean. You can replace only one piston on a rebuild. But you will need all new ringsets. When you get the pistons out of the cyls, you can remove the transferred aluminum- stuck on the cyl wall, with a little muratic acid. Will dissolve the alum and not harm the cast iron liner. You may need to rebore, depending on how worn the cyls and pistons are. Need at least one new piston that will exactly match the other 3. Compare pricing on rebuilding your block vs: a replacement long block, or a complete replacement engine. Then decide your forward path.

 

[dsujen]

can I dump something in the cylinder like kerosine to loosen up the rings to maybe bring the compression up?

 

[emdsapmgr]

Not while the piston is still scuffing the cyl liner. That aluminum transfer occurred due to excess heat. Either it's running lean on fuel or there is a water flow problem around the cylinder liner causing heat buildup. Fix that first.