1996 mercury 115 hp 2+2 engine gear oil

[Johnson110]

I changed the gear oil with 90 weight high performance mercury oil. I notice that the gear casing has 3 screws, bottom which you fill from top ( vent ) which you allow the oil to discharge from when filling, Ok so I see another screw which indicates OIL LEVEL , I removed all three screws and pumped the oil so it started to come out oil level hole inserted screw and than continued to pump oil till it came out of vent hole inserted screw and inserted screw back into lower hole. What is oil level hole for and did i do this right. Always filled from top till oil comes out of vent screw, never saw oil fill screw on lower unit before.

 

[Texasmark]

Drain procedure: Remove all screws with engine vertical. Install new fluid from drain hole and pump till top front hole emits oil....I like to pump a couple more strokes to get some of the bubbles out. Plug vent hole. Continue pumping till the same happens on the aft hole. Plug hole.....per the manual.

 

[Johnson110]

Thanks Looks ok for me. One other question I winterized motor fogged the cylinders but I did NOT drain carbs instead I treated fuel with Sta-bil 360 not the marine formula and ran engine till fogging oil killed it. I see some say this procedure is ok others however say carb must be drained, the drain pugs on lower carbs are a pain to get at, so leaving the fuel treated is ok? The oil injection is hook up working.

 

[racerone]

Never fill an outboard gearcase from the top !

 

[Johnson110]

I did not fill from top, filled from bottom till it came out vent hole and oil level hole. Oil level hole is a new one to me!

 

[MercGuy]

Never fill an outboard gearcase from the top !

Can you explain why ? I have filled from the top for years w/o a problem.

I'm not trying to challenge you, I just want to know your reasoning.

Thanks.

 

[Mohawkmtrs]

Filling from the bottom pushes the gear oil up and also pushes the air out the vent plug so there are no "air pockets" in the gear case,,,and as we all know, air does not lubricate.

 

[Texasmark]

Filling from the bottom pushes the gear oil up and also pushes the air out the vent plug so there are no "air pockets" in the gear case,,,and as we all know, air does not lubricate.

That's the reason. Filling from the bottom you can be sure it's full........of oil.

 

[MercGuy]

I don't want this to become a protracted argument that can't be resolved, so I'll make this one post and let it go. However, I'm not buying it.

I have trouble seeing any difference between pushing oil up from the bottom hole or dribbling it in from the top via an oil can as I do. With my oil can method the oil I pump in most likely runs down the side of the gear case and then the oil level raises just as it would if it were being pumped in from the bottom. The spout of my oil can is roughly 1/3 the diameter of the fill hole, so there is ample room for air to escape.

Try this mental exercise, imagine a bucket with an upside down coffee cup suspended in the middle of the bucket half way between the top and bottom of the bucket. If you slowly pour water into the top of the bucket the water level will rise from the bottom to the top of the bucket and the coffee cup will not fill with water since it is upside down, thus you will have an air pocket.

Now, imagine the exact same scenario, but this time the bucket has a hole in the bottom and water is being pumped in from the bottom at the same slow rate that it was poured in from the top. Can you see anyway that the air will be displaced from the coffee cup resulting with the upside down cup being filled with water ?

I can't.

Like I said, no hard feeling here, not trying to start an argument.

 

[racerone]

All shops fill outboards from the bottom till oil comes out the top.--Ask them.---This is the way it has been done for well over 50 years.

 

[MercGuy]

All shops fill outboards from the bottom till oil comes out the top.--Ask them.---This is the way it has been done for well over 50 years.

Oh, I had no idea it has been done that way for 50 years !! That changes everything...

 

[jimmbo]

It is usually faster to fill from the bottom that trying to squirt the oil in from the top, Less chance of air bubbles too. The old man tried filling from above, lots of spitback and mess.

 

[Texasmark]

Oh, I had no idea it has been done that way for 50 years !! That changes everything...

Because the service manual says so and it also says what that second vent hole is for....... besides 100 years of doing it that way.....but now it's easy, you don't have to stick a tube in the hole and squeeze slobbering oil all over everything. You can affix an adapter that comes with the quart of Quicksilver oil and exercise the pump. Neat and clean.