Water getting into the 4th cylinder..

[Zeke222]

Hi everyone. I'm just new here and am having a bit of trouble with my boat motor. This looks like a great site and I'm hoping that someone will be able to help me. I have a 1991 Mercury Mariner outboard motor. The serial number is ODO70282. It's a 4 cyliner, 2 stroke. The problem is that the engine is getting water into the 4th cylinder. Can someone please give me an idea what the problem might be and how I go about fixing this. Thanks very much!

 

[jerryjerry05]

Re: Water getting into the 4th cylinder..

First thing do a compression test and post the results.Jerry

 

[Zeke222]

Re: Water getting into the 4th cylinder..

Okay, I will try that and get back to you. Thanks for your quick response. I appreciate it.

 

[Zeke222]

Re: Water getting into the 4th cylinder..

Hi Jerry. I did a compression test and all 4 cylinders have 115 pounds of compression.
Thanks again.

 

[Zeke222]

Re: Water getting into the 4th cylinder..

Does anyone else have any ideas? I have the motor all apart and was really hoping that someone might have some ideas for me to try.

 

[Moody Blue]

Re: Water getting into the 4th cylinder..

Likely the lower crankshaft seal has gone. Exhaust water is likely being sucked up past the crankshaft seal into the lower cylinder.