Can Lower Unit Reseal Itself After a Hit?

[muskrat]

I was out muskie fishing last Nov. when I hit a rock on the way into the launch (actually hit it twice as I tried to get out of the area) and dinged my prop . When I went to change the lower unit oil I noticed that there was oil on the inside of the prop and prop shaft area. I figure I lost about half of the oil that was in there but no water got in. I've filled up the lower unit with fresh oil and it doesn't appear to leak.
Is it possible that when I hit the rock that the shaft shifted enough to let oil out under pressure and then resealed itself?

[mikemicropterus]

anything is possible but is that probable, I ahve never heard of this happening but then again I didn't think bush would get a second term so I have been wrong at times.......

I didn't fill your gearcase so i don't know how much oil was in it to begin with, but I'll have to assume it was full...how did you determine you lost half your oil.......you would have seen one hell of a slick behind the boat all day if it was leaking,,,

here's my point if the gear oil got out why did no water get in...as ther gearcase gets hot it creates pressure.....positive...push...as it cools the pressure changes to negative ......suck.....so if you went to you spot and stopped the gearcase should have sucked in water if the gear oil could get out.....if you just trolled around then it would be positive and likely no water getting in......


I suggest you get the gearcase pressure and vacuum checked to make sure....How hard a hit and was it an aluminum prop????

Do you change your drain screw washers each time you change your gear oil??? if not that is probably where the gear oil is going, just a guess mind you... Is the prop shaft bent????

[bigpikemike]

another scenario is and i have fallen for it b4 is....well hard to explain but i will do my best...i would find what looked like to be gear oil on my prop and it was left over gas from the engine leaking through the exhaust picking up sut making it look like oil then drippin on my prop

[mikemicropterus]

Gear oil is clear oil while used exhaust is dirty and black, I'm not sure how one could confuse one for the other...but I geuss anything is possible.....I already considered the spent exhaust residue, the difference would have been the gearscase would not be half full or empty, as some see life, so I don't want to send him down the wrong road with what maybe improper advice...... another BYM

[muskrat]

The prop is aluminum and the hit was hard enough to put about a 1/2 inch notch on each prop blade but there was no chipping or scratches on the gear case itself. This happened late at night so I couldn's see if there was a slick behind me.
I noticed the oil amount was shy a few days after when I went to change the lower unit oil for the winter. There was black oil dripping from the lower unit from prop shaft area and the oil was black when I drained it.
I filled the lower unit and started the motor up yesterday with the muffs on (its a 1990 Mercury 40) and about an hour later I noticed some grey stuff dripping from the prop shaft area. The prop shaft doesn't appear to be bent. The next day I also noticed about an ouce of oil dripped out from the engine that seems to be coming from somewhere around the lower carborator.

[troutnmuskiehunter]

The prop is aluminum and the hit was hard enough to put about a 1/2 inch notch on each prop blade but there was no chipping or scratches on the gear case itself. This happened late at night so I couldn's see if there was a slick behind me.
I noticed the oil amount was shy a few days after when I went to change the lower unit oil for the winter. There was black oil dripping from the lower unit from prop shaft area and the oil was black when I drained it.
I filled the lower unit and started the motor up yesterday with the muffs on (its a 1990 Mercury 40) and about an hour later I noticed some grey stuff dripping from the prop shaft area. The prop shaft doesn't appear to be bent. The next day I also noticed about an ouce of oil dripped out from the engine that seems to be coming from somewhere around the lower carborator.

Why bother messing around with it???....save yourself the aggrevation and take it to a certified marine engine mechanic before the softwater season starts which will be sooner that you think...

[muskrat]

Yeah, I suppose I should...