Mercruiser 3.0 1998 sting ray i/o crankcase vent

davei

Recruit
Joined
Oct 25, 2010
Messages
3
Need some help with a long list of problems.

My boat has not been running well for two seasons. I have a local boat mechanic winterize it and tune it every year. This year the boat had carb rebuilt but still ran horribly. I drained fuel from tank and replaced with 93 oct no ethanol gas.Changed fuel filter and carb screen as well as plugs then ran half tank through it. Filled tank again. Ran great for two days (like new) and came back two weeks later and it took a 20-30 min to start and ran rough and backfired. It was as if i had done nothing. Hesitation was horrible. Was convinced carb was still no good so i sent it off and had it remanufactured. Installed carb and the engine fired on 2nd crank. Took it out ran horribly again.Still backfired.I noticed water droplets coming from crank case vent as well as more than mormal smoke. Let it idle at the dock for two hrs. Took it out and it ran much better. I was running about 3/4 speed and turned and noticed horrible light brown(coffee colored) fluid spraying out of the vent tube. Back off the throttle and it slowed and then limped into dock.Dont really know what to do.The engine temp and oil pressure were still in the normal range.

Thanks for any suggestions

Dave I
 

zbnutcase

Commander
Joined
Sep 19, 2009
Messages
2,055
Re: Mercruiser 3.0 1998 sting ray i/o crankcase vent

Sounds like you are getting water in the oil; thats why its coffee colored. Could be manifold or riser issue, especially if it is used in saltwater, and if it is, its well overdue for replacement. Time to first check the oil and see what it looks like, then pull manifold for inspection, and OIL THE CYLINDERS ASAP to avoid rusting up and turning engine to junk!
 

davei

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Oct 25, 2010
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Re: Mercruiser 3.0 1998 sting ray i/o crankcase vent

Best way to oil cylinders?
 

Fishermark

Vice Admiral
Joined
Oct 19, 2003
Messages
5,617
Re: Mercruiser 3.0 1998 sting ray i/o crankcase vent

Best way to oil cylinders?

Remove the sparkplugs and see if there is any indication of water - probably will be.

While the spark plugs are out, pour some oil in each cylinder and rotate the engine.

Find out where the water is coming from.

(I just went through this with mine, it turned out to be a cracked manifold).
 

davei

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Joined
Oct 25, 2010
Messages
3
Re: Mercruiser 3.0 1998 sting ray i/o crankcase vent

thanks for your help
 
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