Re: Gear Lube
Oh! Here I go again! CAUTION---Science content!
Oil and water don't mix. That's why if you are old enough to remember the old days before homogenized milk, the cream always rose to the top. Then they discovered how to break up the oil particles into small enough drops that they would not separate from the milk. This is called homogenization.
When running, the gears of the lower unit mesh and squeeze the oil between them. Any water present will be mixed into the oil and remain there for a significant time--the oil and water are being homogenized by the gears. Since the particles are mixed, they reflect light and the oil appears milky.
Since the gears are not a true homogenizer and to not break up the oil and water droplets to actual colloidal size (which makes a non separating mixture), eventually the water and oil will coalesce and separate. --That is, when more water is present than the additives in the oil can hold. Then, upon standing, free water will drain from the gearcase first.
OK! Science content finished. You can get the glazed look out of your eyes.
Now, we have established that you have water in your lower unit.
The easiest things to check are the fill and drain plugs. they need to be very tight, not just snug. I like to use a large square shank screwdriver and put a wrench on the shank to tighten. You also need to check that the white or clear plastic gaskets are present and in good condition. On the side of the gearcase is a recessed screw. DO NOT REMOVE IT unless absolutely necessary. It carries the shift mechanism. Be sure it is very tight and to be certain it will not leak, fill the recess with silicone RTV.
Next easiest thing to check is the prop shaft seal. Behind the propeller is a "gland" that carries the rear bearing and seal. It is held onto the gearcase with two allen head cap screws. Remove the screws, tap the gland to twist it some then tap it out of the gearcase. check the condition of the seal. It (and most of the others) is a standard one and can be purchased at your local bearing supply store. The gland is sealed to the gearcase with an O Ring. Replace seal and O Ring if necessary.
Now, the more difficult one: remove the lower unit. The shift rod has a seal. The rod should be tight in it and have no slop but should move silkily up and down with no binding. If this seal is loose you can sometimes use an appropriate sized socket and piece of pipe to hammer it further into the case, compressing it and sealing. Otherwise you need to pull it, and replace. It is probably standard but I have always bought it at the dealer--it's only 7-8 bucks. It is the same for ALL Chrysler and Force 75 hp and up lower units from 1970s to 1990--a part that was never changed.
Below the water pump is the drive shaft seal and it usually fails less often than the others but check it anyway if previous checks and repairs have not stopped water leakage.
You have a two piece lower and you will either have two or three bolts holding the gearcase to the cavitation section. (if you have a six inch long 12 point bolt holding the rear to the midleg, it is a two bolt gearcase unless it has been changed) You will see the nuts in the point of the casting, and forward and behind the water pump. There are O Ring seals under the nuts on top--they would be checked next.
AND lastly, if all else has failed to stop leakage, there is a large O Ring between the gearcase and upper half. This usually does not go bad either so it would be the last thing to check and replace.
