kylerichards264
New member
To start this off this is not my boat. But I am helping the owner out as I would like to learn more about this Chevy 350.
Owner just bought a boat with a mercruiser 5.7 liter Chevy 350 engine in it. He knew the engine was not the best but the whole thing was pretty cheap so here we are. Not sure of the specifics of the engine or the boat, all I know is that this 5.7 was swapped into the boat to replace a V6 I think. But all that does not really matter as I can figure out all of that some other time.
The problem occurred when we decided to do a compression test. As of right now the engine seems to run relatively fine, starts right up. Does not sounds bad but we also did not run it for that long at all since we didn't have a supply of water. White smoke or vapor seemed to be coming from the top of the engine or the carburetor. Not sure what that is but whatever ill figure that out. There is also a tremendous amount of oil below the engine pooled up. But the dipstick says there is oil in the engine. The compression test showed about 150-160 psi on cylinder 1,3,5,7 and about 50 psi on cylinder 8,6,4 and like 125 on 2. So the starboard side of the engine, or the drivers side (I'm a car guy, first time working on a boat) has bad compression on those cylinders which is so strange to me.
Apparently this engine was just rebuilt in 2019, and put into this boat. Apparently it ran fine for an hour or so and then the previous owner decided to floor it and then I guess white smoke started to come out of the exhaust. sat for a while and 4 years later here we are.
I thought water had gotten in through the exhaust risers on 1 side. So I removed the risers and there is a little rust but no clear signs of water rusting through or getting into the engine. We looked into the cylinders with a bore scope and I didn't see anything visually wrong. No sign of water.
I also removed the valve cover and there was no play on any rockers or pushrods. No signs of anything bad.
As of right now my best guess is either a horrible head gasket job or the pushrod rockers were tightened too tight on one side?? Honestly I am really not sure, and then there's the issue with all the oil So I am really not hoping the block is cracked or something. I am doubtful its the piston rings because what are the chances all the rings go bad at the same time in 4 cylinders.
This is my first time working on a boat engine, or a carbureted V8 engine in general. So far this this has been pretty easy to work on so I am not complaining. Took about 3 hours to get the engine prepped for removal for next weekend.
I would like any suggestions any of you have. Even if its to just replace the engine.
Again I am new to all this boat stuff so I wouldn't know anything obviously wrong.
Thanks everyone!
Owner just bought a boat with a mercruiser 5.7 liter Chevy 350 engine in it. He knew the engine was not the best but the whole thing was pretty cheap so here we are. Not sure of the specifics of the engine or the boat, all I know is that this 5.7 was swapped into the boat to replace a V6 I think. But all that does not really matter as I can figure out all of that some other time.
The problem occurred when we decided to do a compression test. As of right now the engine seems to run relatively fine, starts right up. Does not sounds bad but we also did not run it for that long at all since we didn't have a supply of water. White smoke or vapor seemed to be coming from the top of the engine or the carburetor. Not sure what that is but whatever ill figure that out. There is also a tremendous amount of oil below the engine pooled up. But the dipstick says there is oil in the engine. The compression test showed about 150-160 psi on cylinder 1,3,5,7 and about 50 psi on cylinder 8,6,4 and like 125 on 2. So the starboard side of the engine, or the drivers side (I'm a car guy, first time working on a boat) has bad compression on those cylinders which is so strange to me.
Apparently this engine was just rebuilt in 2019, and put into this boat. Apparently it ran fine for an hour or so and then the previous owner decided to floor it and then I guess white smoke started to come out of the exhaust. sat for a while and 4 years later here we are.
I thought water had gotten in through the exhaust risers on 1 side. So I removed the risers and there is a little rust but no clear signs of water rusting through or getting into the engine. We looked into the cylinders with a bore scope and I didn't see anything visually wrong. No sign of water.
I also removed the valve cover and there was no play on any rockers or pushrods. No signs of anything bad.
As of right now my best guess is either a horrible head gasket job or the pushrod rockers were tightened too tight on one side?? Honestly I am really not sure, and then there's the issue with all the oil So I am really not hoping the block is cracked or something. I am doubtful its the piston rings because what are the chances all the rings go bad at the same time in 4 cylinders.
This is my first time working on a boat engine, or a carbureted V8 engine in general. So far this this has been pretty easy to work on so I am not complaining. Took about 3 hours to get the engine prepped for removal for next weekend.
I would like any suggestions any of you have. Even if its to just replace the engine.
Again I am new to all this boat stuff so I wouldn't know anything obviously wrong.
Thanks everyone!
