Mercury 5.7 has Water in Two Cylinders

[eightpoint3]

I am looking to purchase a 1986 Sea Ray with the Mercruiser package that includes the 5.7 L V8 engine.

The owner started having trouble with the engine as he was getting ready to sell it. He has been very forth coming and I believe that this is the complete information.

The unit had problems starting a week ago. A starter was replaced. The engine still had problems. A check of the oil showed an indication of water in the oil. All plugs pulled. The starboard side had two plugs that were wet. The engine was cranked with the plugs out to clear the water. After plug reinstallation, the engine started and ran normally. An attempt to start it yesterday for me failed with the same symptom as last week.

My experience has been with sailboats and Atomic 4 gas engines which ocassionally blow head gaskets. I am thinking head gasket or possibly a cracked head. The boat price has been reduced accordingly but I don't want a new boat in the shop for the rest of the season with an engine swap project if I am wrong.

Has anyone seen this? The front two cylinders on the starboard side appear to be the ones affected. I can't pull the head until I buy the boat...LOL

 

[slia67]

Re: Mercury 5.7 has Water in Two Cylinders

Sounds like you're on the right track, but without being able to work on it it's hard to tell.

Doug

 

[hullofalottatrouble]

Re: Mercury 5.7 has Water in Two Cylinders

you might want to do a compression test on that engine and it might help you diagose the issue with the two wet cylinders and perhaps find other engine problems..

 

[eightpoint3]

Re: Mercury 5.7 has Water in Two Cylinders

Thanks for the info so far!

I will see if the owner will let me do a compression test. We need to clear the water out of the cylinders anyway. It would seem if it was exhaust water, it would be in the whole side rather than just affecting two.

 

[95yj]

Re: Mercury 5.7 has Water in Two Cylinders

Most common way for water to get into a marine engine is through the exhaust system. Next,but much less common would be through the head gaskets. This can be minor if caught early or can be a big problem if you already gernade the motor. At that point, you obviously need a new engine.

Problems starting and "starter problems" can be water in the cylinders that mean hydralocking. At this point, you have water in the cylinders and need to fix the problem but more importantly make sure you haven't broken anything yet.

You can turn a good motor into scrap in a couple of seconds by running it or trying to start it with water in the cylinders; bent rods, broken pistons and the like. If you're buying the boat, you want a guarantee that the motor isn't already trash. Personally, I'd look at another boat unless you really like that one and don't mind doing a repower.