1991 3.0 Mercruiser

[green5743]

Just bought a 1991 Sea Ray 170 with 3.0 Mercruiser. Took into shop and they Replaced carburetor,(Told me gas was getting into oil), new spark plugs, changed oil, new bellows and gimbals, fixed u joint and few other things. Took boat out on the water and when driving the boat it didn't take on water but boat was sitting it did take on some water. It ran great and about 30 minutes in it seemed like the engine bogged down. I took out of water and checked the oil and it was milky gray so I assumed water was getting in the oil. GREAT!!!! took spark plugs out and they seemed little wet. When running the engine there is no water dripping from the engine so I would think its not a cracked block. I did compression test on the cylinders and all cylinders were at 150 so I assume its not a blown head gasket. I have read that the exhaust manifold has a flipper on it that stops the water from rushing back in and that flipper after a period of time can melt away. Let me know what you think? I'm new and don't really want to fork out to much more and would like to fix myself.

 

[Bt Doctur]

what are the first 3 letters of "assume"
Just bought a 1991 Sea Ray 170 with 3.0 Mercruiser. Took into shop and they Replaced carburetor,(Told me gas was getting into oil), new spark plugs, changed oil, new bellows and gimbals, fixed u joint and few other things
What about the impeller, actual on water test run,

driving the boat it didn't take on water but boat was sitting it did take on some water.

How much water and how high was it

It would have to be almost at floor level to get into the motor. If it was not then suspect a cracked block from inproper winterizing or a leaking head gasket from an overheat.
What were the gauges reading on your run?

 

[Scott Danforth]

welcome aboard

first, if gas was getting into the oil, you would not have needed a new carb. fuel pump maybe

learn to do your own wrenching

flappers get burned from lack of cooling water from neglected raw water pump

cylinder head gaskets can go from improper timing and a severe overheat causing the head to warp

the fact that you have good compression would tend to lean toward either a leaking exhaust manifold or a crack in the block

 

[green5743]

When sitting I could flip the bilge on about ever 30 minutes and get out a little. Never enough to get up to the engine. And yes it was on the water on test run. The gauge ran around 170 the whole time on the run. If it was a cracked block wouldn't I see water dripping while the boat was on. I ran on muffs after I changed the oil and the oil looked fine. It wasn't until I put the boat in the water and it was milky grey. I also noticed after I ran in water there was water on the right side of the motor bay as if it hit a belt and sprayed over there.

 

[Scott Danforth]

you should be able to park the boat in the water for weeks (as long as its not raining) and not get a drop in the bilge.

time for you to climb in the bilge with the motor and look for leaks

3.0 blocks can crack both internally and externally. need to pressure test.

 

[green5743]

I'm not familiar with how to pressure test? Can someone help me out with directions?