Thanks, Greg. I'll investigate the method for checking water pressure in the
service manual. If it requires tricky tools, I'll probably just take it to
the dealer. He's very strange: He charges very little, and the service is
great. But, he's 45 minutes away, so I'm trying to frighten myself with
information before surrendering the boat during what could be the last good
weather of the fishing season.

"Greg" wrote in message
...
Mid size Mercs have a known but largely unacknowlaged problem with the
gasket/grommet between the leg and the powerhead.
It took them about 6 months to finally agree my 60 4 stroke was broke.
Have you checked the water pressure?
If it is much below 3 at idle or ~17 over 4500 RPM you should get it back
to
the dealer.