Water in Crankcase 2006 90HP Four stroke

[bruceb58]

2006 Mercury 90 HP Four Stroke. 110 hours on motor.

Took my pontoon out of the water two weeks ago and brought it home. Went to change the oil today and first looked at the oil level.Noticed it was slightly high but clean and not emulsified.

Warmed up the engine and then pulled the drain plug that is on the port side of the outboard. If you are familiar with this outboard, it is around a foot down from the power plant. About a half quart of water came out followed by some slightly emulsified oil followed my mainly normal looking oil.

I added new oil and filter and ran it for 20 minutes. Oil has a slight hint of emulsification but not very bad at all. Probably from what was left in the crankcase.

I am confused on how water could have gotten in.

Temps at the lake had dipped down to 30 for two nights prior to me taking the boat out. Motor was not tilted out of the water.

 

[Silvertip]

Engine running too cool and since this is a pontoon, likely running long periods at low rpm thus never getting hot enough to burn off condensation. That's the simple explanation. Not so simple is a head gasket or other engine problem.

 

[Faztbullet]

Be sure to check the thermostat. If it's stuck open your engine will run too cold and this can cause a 4 stroke to "make oil". Actually it's adding condensation to the crankcase, and because the engine doesn't get up to proper temp the condensation fails to boil off. Also,it can make the engine will run too rich because of improper temp. There is a Mercury TSB out on this....

 

[bruceb58]

There is a Mercury TSB out on this....

You happen to have a link to it? I have a Rinda and I actually did get an over cooling code set.

 

[bruceb58]

Been doing some searching and most of the problems seem to be fuel diluting the oil. What I have is definitely water.

 

[bruceb58]

Be sure to check the thermostat.

I followed your advice and pulled the thermostat. It is stuck open.

You got me thinking yesterday. When I had my Rinda on the motor, I never saw it getting over 97?.

 

[Faztbullet]

There ya go...

 

[bruceb58]

Thank You.

 

[Fun Times]

Be sure to check the thermostat. If it's stuck open your engine will run too cold and this can cause a 4 stroke to "make oil". Actually it's adding condensation to the crankcase, and because the engine doesn't get up to proper temp the condensation fails to boil off. Also,it can make the engine will run too rich because of improper temp. There is a Mercury TSB out on this....

Nice job Faztbullet...Plus with me liking your post above maxed out your amber colored bar under your username which was well deserved years ago AKA the day the forum started using them.:facepalm: Seriously, thanks for all you do here.

bruceb58 you have a PM that could lead to more questions for Faztbullet :becky:

There is a Mercury TSB out on this

Do you by chance recall the year or number or?

 

[Faztbullet]

Do you by chance recall the year or number or?

Will check and find it.....

 

[bruceb58]

you have a PM that could lead to more questions for Faztbullet :becky:

Yes, Fun Times was recommending pulling the plugs and possibly getting a scope to look at the cylinders for wear. I did look at the spark plugs to see what they looked like and they look fine. Not sure if I need to do anything else to determine if any damage has occurred. Last time I had the boat out it seemed to run fine although I have noticed less power lately which I was chalking up to more growth on the pontoons as it had been in the water since April. Maybe I will do a compression check. Fun Times had mentioned that maybe running cold for along time could have caused ring issues.