Filling Bravo Outdrive Oil Not Connected to Boat (Reservoir)

[pyrotek]

What is the preferred method of filling outdrive oil when not connected to boat and therefore not connected to oil reservoir on engine. I can only fill up to the top vent hole. When I go to reconnect it, I'll have a pocket of air on top of outdrive and in oil hose. Shops must do this all the time.

Seems like a basic question, but I have never done it before and surprisingly can't find the answer.

 

[scoflaw]

No problem the air will purge

 

[pyrotek]

So why pump up from the bottom?

 

[Scott06]

So why pump up from the bottom?

only way to get the air out given the small passage between the two halves of the outdrive. This is different than the small amount of headspace in the drive above the upper vent plug. When that gets moving the oils splashes around and all parts stay lubed.

if you tried filling from the top you’d never get enough air out to get the lube in. If it really worries you put the drive on it’s side with vent plug up and you can purge this air pocket out but not really necessary

 

[GA_Boater]

If Merc thought there should be no head space, the vent would be in the top cap. The air space allows for expansion so seals don't blow out.

 

[JASinIL2006]

I fill mine upright until lube comes out the vent hole, then I lay it on its side and add more until the lube again runs out the vent. It still has some air in it, because when mounted on the boat, the level in the reservoir will drop. When I don’t top it off by laying it on its side, the reservoir will drop 50% or more of its contents into the drive.

 

[tpenfield]

My home grown method . . .

Lay the outdrive on its port side (oil fills facing up). Have the 'top' of the outdrive raised slightly and fill from the bottom oil fill hole, using the Mercruiser oil pump (hand pump), allowing air to escape from the 'top' oil fill hole.

Once the oil gets to the top fill hole, bring the outdrive to nearly flat, with the top of the outdrive raised only about 1". . . replace the bottom oil fill screw cap and then manually fill any remaining oil from the top hole until you cannot get any more oil into the outdrive.

Replace the top cap and install the outdrive as/when desired.

 

[harringtondav]

Fill it per the above advice, to the top vent hole. After you install it remove the reservoir cap and add lube per process from the drain port. Watch the reservoir, or have a helper watch. You may see bubbles, maybe not. But when the reservoir level rises, you're good to go.

As stated above, if you do nothing the air will purge into the reservoir and the level will drop a touch. Top it off to the full line and move on.

The lube monitor system was a great Merc improvement. After I service my Alpha II the lube level always drops, then holds...assuming good seals. The check valve reservoir cap causes the drive to pressurize when warm, preventing water from entering the seals. As it cools, the check valve allows air to replace any lost lube, vs water being sucked in past the seals.

 

[pyrotek]

Thanks. I filled up to vent hole. What I forgot to mention is that

I pulled engines and transom assembly for steering pin repair. So my oil lines are full of air. I'm thinking its a good idea to fill the reservoir and manually push the valve open until oil starts filling the oil hose. Under normal circumstances the hose is filled with oil.​

I might also take tpenfield's approach and tilt on side and fill last bit into vent hole just for extra piece of mind. Although this is all likely to leak out when I go to reinstall the outdrive, which is always a mess for me, before I can torque down the bolts.