I have a 85 Jonhson 15hp (J15RCOB) with low compression (60 & 70, spec is ~115) and low flow out the tell-tale. I have already replaced the impeller, which made a small improvement in the tell-tale flow.
I have receive mixed advice on decarbing and I am leaning towards not doing it as the compression appears to be coupled with a water/cooling problem.
Here's my deduction...the older impeller ran the engine a bit warm resulting in a blown head gasket. Possible cause...the grommet on the upper end of the water line is dislodged.
From looking at the engine it does not appear difficult to replace the head gasket. But I do not want to go through the effort without correcting the cause. Am I over-simplifying the gasket job? How difficult is it to replace the grommet? Any other possibilies that I should investigate?
Thanks for your help, Ken
I have receive mixed advice on decarbing and I am leaning towards not doing it as the compression appears to be coupled with a water/cooling problem.
Here's my deduction...the older impeller ran the engine a bit warm resulting in a blown head gasket. Possible cause...the grommet on the upper end of the water line is dislodged.
From looking at the engine it does not appear difficult to replace the head gasket. But I do not want to go through the effort without correcting the cause. Am I over-simplifying the gasket job? How difficult is it to replace the grommet? Any other possibilies that I should investigate?
Thanks for your help, Ken