Tennessee's Fishing and Boating Community

Go Back Tennessee's Fishing and Boating Community > Mid South Outboards > Projects
Register FAQ Members List Calendar Mark Forums Read

Thread Tools
Old 09-04-2018, 09:17 AM
jaybird's Avatar
jaybird jaybird is offline
Senior Member
Join Date: Nov 2015
Location: Mount Juliet, TN
Posts: 268
Default Lower unit


I have a 1983 Johnson 70 hp outboard. I have owned it for 4 years or so. I went to change the lower until fluid last weekend and the only thing I got out was water. I filled it and used it twice this weekend with no issues. My guess is I need to replace the seals on my lower unit. Is this something I should attempt myself and is it something one guy can do by themselves or is the lower unit removal a two person job. Any advice would be appreciated.
Reply With Quote
Old 09-04-2018, 11:31 AM
tkwalker's Avatar
tkwalker tkwalker is offline
Owner and Administrator
Join Date: Apr 2005
Location: Lebanon, Tennessee
Posts: 2,925
Smile Lower unit seals ... <'TK><

The lower unit can be removed by yourself. Sometimes it helps if there are two people to help go back with it .. You will need to align the water tube, engage the drive shaft into the crank while turning the flywheel until the splines match.

As far as the seal leak 90% of the time it is the shift linkage "O" ring seal. I haven't replaced a 3 cyl. 70 hp OMC in a while and off the top of my head can't remember the the logistics of removal and replacement ...(Is it an electric shift?) It would also help if you pressurized the lower unit with about 7 PSI of air and check all of your seals via Soapy water ...

While you are there you might as well change the Water Imp. Now if you want to make this a winter project and it seems this is not a fast leak, Just keep an eye on it .. It takes 3 to 5 days for the water and oil to separate. The first thing out will be the water out of the bottom fill hole or it may be milky. you do not need to dump all of the oil ...Just add until it clears up coming out of the upper vent... Quicksilver High Performance HyPo 80/90/ will mix with water and continue lubricating ... Hope this helps <'TK><
Reply With Quote

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT -5. The time now is 04:59 AM.

Site best viewed at 1280X1024