I have a 1986 15 HP which has been running perfectly until recently. I
hadn't used it for two years and not knowing anything about outboards
except where to start and steer. The motor overheated while cruising
and it shut down and became very hot.
Some hot oil was forced through one of gaskets. I brought the unit to
a repair shop and they told me the impeller was gone so it overheated.
He measured the compression which is now 80 lbs and 85 lbs. He told me
that the motor would be too expensive to repair. Could it be that a
blown gasket is the reason for the now low compression. The cylinders
look fine to the eye. I'm thinking about buying a shop manual and
trying the impeller and gasket replacement.

Any thoughts?

"rescued beagle" wrote in message
oups.com...
I have a 1986 15 HP which has been running perfectly until recently. I
hadn't used it for two years and not knowing anything about outboards
except where to start and steer. The motor overheated while cruising
and it shut down and became very hot.
Some hot oil was forced through one of gaskets. I brought the unit to
a repair shop and they told me the impeller was gone so it overheated.
He measured the compression which is now 80 lbs and 85 lbs. He told me
that the motor would be too expensive to repair. Could it be that a
blown gasket is the reason for the now low compression. The cylinders
look fine to the eye. I'm thinking about buying a shop manual and
trying the impeller and gasket replacement.

Any thoughts?

What have you got to lose, other than a $100 bucks or so. And think of the
fun and experience gained in working on it yourself. It may never run like
a new one if the cylinders were scored badly and may even disintegrate if
the rod bearings were ruined but what the heck, you could replace them, too.
I would imagine your mechanic was considering his $50 per hour shop rate and
that would truly make it not worth repairing. For what it's worth, 50 years
ago, I ran a 16hp Johnson on a little hydroplane (for fun only). Its design
didn't use an impeller but had scoops on the prop that forced the water
through the engine. I replaced the prop with a "speed prop" without the
scoops and relied on speed to force the water up and through the engine. Of
course if I idled too long or leaves blocked the lower unit intake, the
engine would overheat and seize. I'd let it cool down and run it some more.
Two or three times a summer, I'd tear it down and replace the rings and
gaskets. It was still running when I sold it to a buddy. Of course, I was
only 16 at the time and what else did I have to do.

Tom G.