Filling a 75 hp lower unit

[911rsr]

I purchased a 1980 75 hp Chrysler outboard that has not ran in awhile so I am cleaning it up and working on getting it started. My question regards filling the lower unit with oil. There is a "fill" hole at the bottom of the lower unit but it is in the prop torpedo and recessed into the case about 3/8". There is a plug marked VENT at the top of the case and a plug marked FILL at the top of the case. I have never seen a fill plug at the top of the case before and I want to be sure I should be filling the case at this upper plug? Also does anyone know the capacity of the lower unit?

Thanks

 

[milehighboater]

Re: Filling a 75 hp lower unit

I do not know much about that motor, but my 1999 75 hp force lower takes about a half a quart... but fills from the bottom until lube pours out the "Full" hole. Use a small pump that screws onto the top of the lube bottle. They are about 6 dollars and you should be able to find them at any autoparts shop.

 

[roscoe]

Re: Filling a 75 hp lower unit

Always fill from the bottom, it forces all air out the top.

Doesn't work to pour in the top as the air is trapped inside the unit and the lube can't get in.

There are a few units that have the fill and vent holes at the bottom, but most have the fill at the bottom and the vent at the top.

 

[Frank Acampora]

Re: Filling a 75 hp lower unit

1980 is a one piece lower unit with three plugs. The lower plug is drain only, top two are fill and vent as marked. Internally, fill is an open chamber into the bottom of the torpedo while vent has a small hole in a web about 1/3 of the way up. Oil runs down into the torpedo while air is displaced through the hole then later, as the unit fills, oil comes through.

Remove all three to drain the unit with the engine in vertical position. Replace the bottom plug and fill through the fill hole until oil comes out the vent. let sit for about 1/2 hour to let air rise and then top off again. Close all three plugs TIGHT---replace the gaskets if in doubt of their condition.

Filling this way prevents losing any lubricant as you try to replace the lower plug--makes sense--since the upper bearing has no forced oil and since it is at the level of the fill and vent, it is imperative to retain all the lubricant to prevent the bearing running dry.

Lower plug is NOT on the side of the torpedo--that is the shift pivot and is recessed.

Chrysler used three different types of drain plugs: A slotted flat top 3/8 plug in front of the skeg, a slotted flat top plug on the bottom of the torpedo and on the side of the skeg, a 5/16 allen head set screw in front of the skeg, and a 1/4 NPT slotted pipe plug in front of the skeg. Yours will be one of those.

Note: the pipe plug and the 5/16 set screw do not have gaskets. Coat with anti-seize or teflon tape before replacing

 

[karatejoe]

Re: Filling a 75 hp lower unit

what they said and dont forget dawn dish soap to wash the lube off your hands. It works great for getting it off.
Because, you will get it on your hands and your favorite shirt.

 

[911rsr]

Re: Filling a 75 hp lower unit

1980 is a one piece lower unit with three plugs. The lower plug is drain only, top two are fill and vent as marked. Internally, fill is an open chamber into the bottom of the torpedo while vent has a small hole in a web about 1/3 of the way up. Oil runs down into the torpedo while air is displaced through the hole then later, as the unit fills, oil comes through.

Remove all three to drain the unit with the engine in vertical position. Replace the bottom plug and fill through the fill hole until oil comes out the vent. let sit for about 1/2 hour to let air rise and then top off again. Close all three plugs TIGHT---replace the gaskets if in doubt of their condition.

Filling this way prevents losing any lubricant as you try to replace the lower plug--makes sense--since the upper bearing has no forced oil and since it is at the level of the fill and vent, it is imperative to retain all the lubricant to prevent the bearing running dry.

Lower plug is NOT on the side of the torpedo--that is the shift pivot and is recessed.

Chrysler used three different types of drain plugs: A slotted flat top 3/8 plug in front of the skeg, a slotted flat top plug on the bottom of the torpedo and on the side of the skeg, a 5/16 allen head set screw in front of the skeg, and a 1/4 NPT slotted pipe plug in front of the skeg. Yours will be one of those.

Note: the pipe plug and the 5/16 set screw do not have gaskets. Coat with anti-seize or teflon tape before replacing

You hit the nail on the head.

Thanks