1967 Johnson 6hp - lower unit questions

[tml1138]

Model CD-24. Did they make these years and sizes in electric shift? I'm not familar with the differences, only that I'm using common sense that this is just manual due to the fact that there's no wires going to the lower unit.

This leads to my main question. Service manual says to use OMC Type C lubricant in the lower unit. I have some 80-90w gear oil already, for automotive. I know I'm not the first to ask, but I've not seen anyone ask in regards to the motor I have.

I'm thinking if it's just manual shift, then nothing special over regular gear oil here, except maybe to be sure it has additives to keep from foaming should water penetrate into the lower unit case. Which I think all modern gear oils have this anyways.

I can't find OMC Type C locally (so far), and I'm trying to look for standard "Marine Gear Oil" if I should at least do that.

Thoughts?

Thank you.

 

[kfa4303]

Re: 1967 Johnson 6hp - lower unit questions

Hi tm. No electric shift on these little, old motors, although some of the large hp OMC motors did use selectric shift, but it can be a nightmare. No need for any special oil in the LU. Just regular 80/90w hypoid, outboard lower unit gear oil. You can get it at Wal-mart, as well as many auto parts and boat stores. One quart will be enough for several fillings. You'll also want to get a little hand pump like in the pic below. There are lots of brands, but it doesn't matter which one you get as long as it's the right weight.



How to Change Gear Oil in an Old Outboard Motor - YouTube

 

[Fleetwin]

Re: 1967 Johnson 6hp - lower unit questions

Replace the fill/drain plug o'rings too.

 

[tml1138]

Re: 1967 Johnson 6hp - lower unit questions

Yeah I think the automotive 80w-90 I have would work, but I guess the marine type is the best way to go. My motor is a bit different with the plugs. It has a fill plug and one on the same side at the clear at the bottom, marked drain. Ok makes sense to me until I read the service manual. It says to open the drain plug and insert a tube into the hole. Then open the fill plug and fill up until it is just dribbling out of the fill hole. But with the drain plug open....huh? Not sure how that is going to work. I'm thinking I'm going to leave the drain plug in when I do this and fill it up.

Thanks for the replies.

 

[nwcove]

Re: 1967 Johnson 6hp - lower unit questions

You drain and fill you lu through the same bottom plug. Top plug is just a vent so to speak. When the oil drips from the top hole, put the plug back in tight. Then remove the filler pump from the bottom hole and put the plug back in. ( you will lose a bit of oil while doing it!).

 

[kfa4303]

Re: 1967 Johnson 6hp - lower unit questions

+1. You start by rmoving the VENT screw, followed by the DRAIN screw. You then allow all of the old oil to drain. After all of the old oil is gone, you can thread in the plastic tip of the hand pump and begin to re-fill the gearcase from the bottom up as nwcove said. Once you see fresh oil come out of the upper, VENT hole, you can then replace the screw along with a fresh washer. You can now remove the pump from the lower hole and quickly replace the DRAIN screw along with a new washer. You'll have a bit of oil dribble out, but that's ok. Wipe off any excess oil and you're good to go. Whatever you do, don't fiddle with the small, phillips head screw.

 

[tml1138]

Re: 1967 Johnson 6hp - lower unit questions

Ok will do. It seems backwards to do this way. After fully draining, I can't just fill at the top vent hole until it dribbles out? I believe you if it has to be done the way you say, and I'll need to get a hand pump to do this then. I am at least curious why it has to be done the way you guys describe.

Thanks!

 

[nwcove]

Re: 1967 Johnson 6hp - lower unit questions

Ok will do. It seems backwards to do this way. After fully draining, I can't just fill at the top vent hole until it dribbles out? I believe you if it has to be done the way you say, and I'll need to get a hand pump to do this then. I am at least curious why it has to be done the way you guys describe.

Thanks!

its done that way to ensure all the air is out and the lu is actually full of oil. you can fill from the top if you wish, but it will take you hours to do ,and you still wont be sure that air isnt trapped in the gearcase.

 

[boobie]

Re: 1967 Johnson 6hp - lower unit questions

Filling from the bottom takes the air out of the G/C. DON'T fill from the top or you'll run into big problems. Been there with customer who did.

 

[tml1138]

Re: 1967 Johnson 6hp - lower unit questions

Ah, purging out the air. Ok well I got some 80W-90 marine gear case oil and a hand pump from Wal-Mart last night. I had to go to one further away because Walmarts near me don't normally stock marine stuff.

Thanks for all the feedback on this and patience with an outboard motor newbie.