Long story shot is a have a P.I.T.A. 21ft Checkmate starflite with a water pressure issue in the engine.
At idle i have 9 PSI but just off plane i drop to 1-2 PSI which is not good. Engine has new head gaskets, poppet valve, temp sensors, base gaskets, mid plate gaskets, two water pump kits.... With no change in my concern. Only thing left is someone installed a low water pickup on the drive but i feel the water pump in the lower unit is not getting enough water volume due to a huge restriction in the inlet due to the low water pickup kit.
Bought the boat broken so i dont know the history only know the present. Local Mercury dealer has given up and said come get it and bring us a check...

Im hoping to find someone that has a complete lower unit with a 20" input shaft that i can swap onto the engine to prove out my idea.

Cell is 810 397 8375 call and text let me know what you have that might work.
Thanks Kyle

to bad I just sold my last 20" i would have let you borrow it, I would think when they put the cone on that some of the bonding agend dripped or leached into the origional pickups inside

do you have a 1 pc exhaust plate or a 2 pc?

What is your pressure while on plane?

Being new to the OB world, how do i determine if i have a 1 pc or 2 pc exhaust?

Im thinking its something to do with the lower unit, But just paid big money to have all of the internals rebuilt. The builder said he didnt see any issue with the low water pickup kit.

Could you pull the impeller out and replace the housing then pour water in the housing outlet to see how it flows out of the pickup ?

The engine has plenty of water pressure at idle and off plane(9PSI). But when the boat is on plane, water pressure drops to 1.5 PSI. and then the temp raises. Once the is back to no wake and the engine RPM is at idle the water pressure returns to 9 psi and the engine temp drops to a proper operating range.