cooling water

Need help. My boat is no longer huffing with the engine (Universal M25 XPB) running (i.e. cooling water is not being expelled). There is a distinct sound when water is flowing through the system. That sound isn't there. It sounds like the seacock is closed (it isn't). When the water exhaust port...

Had a small leak at shaft of Sea Cooling Water pump (Johnson). Took it out to change the lip seal, impeller and cover o-ring. Just today run the engine and the exhaust (underwater) sounds very funny. Spent hours tracing cooling water from intake thru to Mixing Elbow. Everything looks right just...