seawater in cylinders

[proline2550]

Just got back from a 3 1/2 hour, one engine ride in 3 to 5 footers, fun! 2 trips ago, while in rough water, I had one engine become hydro locked and was unable to turn it over until removing the plugs and blowing out the naughty H2O. After getting a look at the risers and seeing their condition, I was prone to blame them for the problem. I changed all four on both engines. That was three, calmer, trips ago. Today, while fishing a reef site in very snotty ocean, both engines had a hard time starting seemingly from a low battery, both mind you. I was able to start them and we went on to the next fishing site. I did not shut off the starboard engine, so the batts would charge. When the time came to start the port engine. BAM, hydro locked. I pulled the plugs and cleared them out. Can anyone else think of a way that seawater can get into the cylinders other than a rotted riser? I think that the answer has to be the check flapper in the exhaust at the bottom of the elbow, after the riser. Some how, when the boat is in rough water and rocking the water has to be forcing it's way in and down through the exhaust riser and through any open valves once it is shut down. The engines are 1994 mercruiser 4.3 liter, with alpha I gen II drives. Fresh water cooled.

 

[Boatist]

Re: seawater in cylinders

Proline<br />I would also check the exhaust manifolds, a leak there will cause the exact same problem. If the risers are not high enough sea water can be forced up and over. Reread your post and see engines are fresh water cooled but is the manifold fresh water or sea water?<br />Good luck and please come back and tell us what you find.

 

[cmyers_uk]

Re: seawater in cylinders

I had a very similar problem with a Volvo Penta 4.3 where if the kill switch operated, the water slamming into the stern would force up the exhaust into the engine. Subsequent investigation uncovered that Volvo do not fit flappers anymore as they were prone to getting stuck and they rely on the height of the risers above the waterline. On a previous post DON S put this link up which gives really good advice on how to track down water in the engine and how its getting there. <br /><br /> http://www.boatfix.com/merc/Bullet/01/01_13.pdf <br /><br />Don hope you dont mind me using your posts!