Pro active maintenance performed for the new boating season. Replaced impellers and orings for raw water circuits on both engines. Brass pump housing was smooth and clean on the interior, I also used a generous amount of silicone paste lubricant on the impeller.



Start port engine and expect to see flow out my exhaust port within 15-20 seconds, after 30 seconds no water. Waited another 20 seconds and shut engine down. Verified 1.Raw Water Thru hull is open and flow is unobstructed
2. Strainer free and clear

Removed the raw water pump and verified no issues with plumbing of hoses and new impeller and oring. All was still good.
2nd attempt to start and same result.

Closed raw water seacock, removed hose and connected a city water supply, started engine and after 15-20 seconds I can hear the muffler downstream of the exhaust manifolds filling and see exhaust water flowing. At this point I am thinking somehow the circuit was air bound and the pump could not overcome a pocket of air.
Re attach hose to thru hull, open thru hull, start motor and once again, no raw water after 45 seconds.

Out of frusrtation and day light burning I attempt the starboard motor and to my dismay same problem, but when city water was fed through the 1st hose after the thru hull, the water flows through and exits the exhaust port.

I am really scratching my head here, has anyone experienced any thing like this. Any help is greatly appreciated.