Water in lower unit

[bsucatfisher]

Hey guys I wanted to pick the brains of people that know more than I do. Earlier this winter I checked my lower unit oil and it did have some water in it. It was just as the temps were getting down to freezing at night so I drained it. I wanted to take it out one day this winter and filled it with new oil and used it once or twice that week. When I brought it in the shop to change my trailer lights I noticed there was oil where the top of the shaft cover meets with the bottom of the motor cover. This is the seam right below the exhaust. Where should I start in the way of checking seals and which ones are probably bad. I was thinking it was the lower unit seals but wasn't sure once the oil started leaking at that seam. Thanks in advance for the help.

FYI It is a 2001 Mercury 40hp 2 stroke.

 

[crem1]

Re: Water in lower unit

Two easy areas to get into are the washers for the lower unit oil screws and the base plate of the water pump

 

[Texasmark]

Re: Water in lower unit

What engine? Most Mercs nowadays have thru prop exhaust and there isn't any seam below the prop.

Mark

 

[bsucatfisher]

Re: Water in lower unit

What engine? Most Mercs nowadays have thru prop exhaust and there isn't any seam below the prop.

Mark

I am not sure exactly what motor it is. It is a tracker motor by Mercury.

 

[Texasmark]

Re: Water in lower unit

I am not sure exactly what motor it is. It is a tracker motor by Mercury.

Ok, be specific, where is this seam you are referring to?

Mark

 

[bsucatfisher]

Re: Water in lower unit

The seam I am talking about is at the top of the shaft. It not actually on the lower unit itself. Does this make any sense?

 

[Texasmark]

Re: Water in lower unit

Lower unit oil only goes up to the vent hole(s)...my 90 happens to have 2. If you are above that and you see oil it is engine unburned oil, unless by remote chance the upper drive shaft seal has ruptured and the oil that is wicked up there is leaking out. However, if that were the case, you could verify it by checking your lower unit oil level. If still full, it's not lower unit oil, it's combustion oil residue and probably due to the cold weather.

Mark