Rattling noise on 380 Sundancer 8.1 Horizons

[Markd52]

July 13th I posted a thread about a rattling noise that sounded like nuts and bolts bouncing around in my bell housing. Well I took some advice and changed the plugs, the old ones did look bad. I started her up and brought her up a normal temp and she was still running rough. Shut her down and then tried again only to find her Hydro-locked. Pulled the plugs and cylinder #1 and #7 had water in them.. #1 was heavy with water and # 7 was slight. #1 and #7 are on the same head, #1 in the front and #7 in the rear. I shut the seacock and drained the manifold. Cylinders had sea water in them not antifreeze. Cranked the engine and blew the water out of the cylinders and then sprayed CRC heavily in the spark plug holes. Removed the riser and that looked great. Looking into the opening on the manifold also looked real good. Engine oil did not appear to be milky but won't know for sure until I drain it. I did notice the oil pressure was only 20 PSI as opposed to the normal 40 at idle. Boat was a fresh water boat since new in 2002 until I put her in salt water for the first time in just past May. Anyone have any ideas how this sea water is entering the cylinders.

 

[Sea Ray Mark]

Sounds like it could be a classic reversion problem except that it's kind of weird that the water is in #1 & #7 instead of being in the center two cylinders. Mark

 

[Air O'Nautical]

July 13th I posted a thread about a rattling noise that sounded like nuts and bolts bouncing around in my bell housing. Well I took some advice and changed the plugs, the old ones did look bad. I started her up and brought her up a normal temp and she was still running rough. Shut her down and then tried again only to find her Hydro-locked. Pulled the plugs and cylinder #1 and #7 had water in them.. #1 was heavy with water and # 7 was slight. #1 and #7 are on the same head, #1 in the front and #7 in the rear. I shut the seacock and drained the manifold. Cylinders had sea water in them not antifreeze. Cranked the engine and blew the water out of the cylinders and then sprayed CRC heavily in the spark plug holes. Removed the riser and that looked great. Looking into the opening on the manifold also looked real good. Engine oil did not appear to be milky but won't know for sure until I drain it. I did notice the oil pressure was only 20 PSI as opposed to the normal 40 at idle. Boat was a fresh water boat since new in 2002 until I put her in salt water for the first time in just past May. Anyone have any ideas how this sea water is entering the cylinders.

Got to ask...are the manifolds original?

 

[Sublimetime]

Just a guess----number 1 or number 7 cylinder has a bad valve seat or bent push rod, valve not seating is causing water reversion into cylinder because of camshaft/valve overlap.

Do a compression check all cylinders ---when these motors have a miss in them they make the transmissions rattle real bad.