2001 90 hp Merc 4 stroke

[fastfish]

Hi!
I have a 90 hp merc 4 stroke that has water in the motor oil. This motor has 500 hrs and has great compression and runs good. I noticed a small amount of water in the oil the last 2 times I changed it and thought it was condensation. I ran 8 hrs and pulled the plug and had quite a bit more and this time the oil was milky. I changed the oil plug and gasket. I am a tractor mechanic and have worked on outboards a little. What is the next thing I should do. The local dealer has no answer. Please help!!!!
Thanks!
Charlie

 

[alana]

Re: 2001 90 hp Merc 4 stroke

you will find that the water pipe that goes through the sump/ oil pan has corroded where it goes through the grommet. see the diagram in the parts shop on this site i`ve seen this before. one of the reasons i went back to 2 stroke

 

[alana]

Re: 2001 90 hp Merc 4 stroke

look in parts list under "exhaust plate" it is part 814080 or 8140800001

 

[yamamarinetech40]

Re: 2001 90 hp Merc 4 stroke

Yep, Yamaha revealed to us(unofficially) @ last seminar that they too are having BIG problems with the exhaust plate on SOME of it's engines REALLY corroding....but have changed material....will probably see quite a few in months/years ahead with problems.....