Re: 9.9/15 impeller housing tricks?

[Don]

You mention that the engine would give an occasional squirt from the telltale, did it ever puff steam out of the telltale? I am asking only because this was usually a good indicator for me (way back in the day) that the upper water tube grommet was crushed. But, you have mentioned that grommet is OK.
Please correct me as I review what I am recalling from your posts. You have had the thermostat out and checked it in hot water? I do remember something about your pyrometer taking a swim though. Most of the OMC thermostats have a little bleed hole/slot allowing a bit of water to "bypass" it. So, I’m thinking that a stuck (closed) thermostat would allow some water to flow from the overboard indicator in most instances, even though the engine would eventually overheat.
Have you replaced the water pump since the first time you had the gearcase off?
You have had the powerhead and the inner exhaust tube off, found no grommet problems.
You had the thermostat out, but have you had the cylinder head off?