Over heating omc351

I have a over heating 351 /omc

I have a over heating 351 /omc selectomatic...put another unit on and still over heats...installed a complete waterpump kit per manual instructions..still over heats..runs at 180 with the garden hose hooked up at the fitting on the starboard outside location..with the boat in the water with the engine not running i pulled off the inlet hose from the nipple and water flows in very slowly...start the engine and the level drops and burps up about 4 inches every now and then....with the garden hose it comes up 4 inches with a steady flow ...the screen on the bottom of the unit is clean...this is a salt water boat..any ideas?

This is a 1976 boat

This is a 1976 boat

"look on the front side of you

"look on the front side of your lower unit -at the bullet shape on the front side, there is a hole there- inside that hole is a grease fitting - pump about 20 shots of grease into it. Quite common for the swivel area to suck exhaust gases instead of water if not greased. You might need to buy one of those grease guns for u-joints - the hole isn't big enough for full size grease gun tip."