View Full Version : Lower unit

09-04-2018, 09:17 AM

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.

09-04-2018, 11:31 AM
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><:)