Confused

[Cardsharkhere]

bought a I/O and started winterizing it. Drained all the lower casing oil (had some water in oil) Started refilling the oil (both screws out). All of a sudden the oil in the boat pressurized and the pressure was causing oil to come back through the pump. Take a closer look and the top screw hole has a white plug that was behind the upper screw. What is this white material has the consistency of chalk? This is a Midwest boat so I do not believe it is salt

 

[GA_Boater]

Howdy, Gambler.

What I/O are you working on?

 

[scoflaw]

Aluminum oxide created by the stainless screw in the aluminum housing.

 

[wahlejim]

A couple of things going on here that should be addressed. I agree with the comments about the aluminum oxide. It is not uncommon. Make sure all of your zinc anodes are in place to minimize this corrosion. Freshwater boats don't need as many as saltwater boats, but they are still necessary to reduce the corrosion.

I am more concerned about the water in oil. Keep the unit drained and perform a pressure test. You have a failed seal somewhere that you should fix to prolong the life of the outdrive.

 

[Cardsharkhere]

1996 Glastron Boats GS-185 Merc Cruiser

 

[garbageguy]

If you're in fresh water, and especially if your having a galvanic reaction problem, suggest use of anodes made from a "softer" metal such as magnesium or aluminum

 

[Cardsharkhere]

Thanks, at least I have an Idea where to go from here. The oil looked mostly green (No issue) but you could see small amounts of a milky color in the oil. Prior owner stated that he felt it is a closed system and he never have changed the lower casing with oil. The boat ran well this fall after buying it. I was just not comfortable with not replacing the lower units oil, then fell into the issue. Thanks.

 

[GA_Boater]

Wait a minute - Something is wrong here. The upper vent screw threads would be splashed with lube, so how could an oxide block form?

What screw did you remove?

 

[Lou C]

Post up a pic. Alu oxide in a fill plug hole does not sound right. My Cobra has been moored in salt water for 15+ years and I never had that.

 

[H20Rat]

Betting you possibly removed the two bolts at the top of the gimbal housing, since you mentioned 'both' screws out. That would also explain why it was pressurized, there was no air leaving.

But yes, pics...