'08 Merc 60 4 stroke, wont circulate water with thermostat in housing?

[Deep cove marine]

Got a 60hp 4 stroke, wouldnt pump water, brand new impeller. When the thermostat is out of the housing it pumps water great out the exhaust and the TT. With old, and then brand new thermostat, zero water flow. Thanks for any input!

 

[RideNFishCA]

Strange. Obviously you replaced and tested the thermostat. The part that is weird to me (no expert here) is the TT should work all the time. It doesn't need the therm to open for it to work. It is on a separate line ahead of the therm.
Good luck.

 

[Deep cove marine]

I know it, there must be a clogged bypass water circuit or something. When I hook a garden hose directly to pickup tube, therm removed, water shoots out the telltale like 15'. With thermostat in, can't even blow air up the pickup tube.