can someone explain how to change the lower unit lubricant.

i have a 1986 150 mercury

i'm having a friend(that knows what he's doing) help me.  but i was wanting to get an idea of whats going on before we do this.

Outboard should be near vertical when filling/draining.

1. Place a container under foot to catch fluid.

2. Remove lower drain plug.

3. Remove upper plug to allow air to replace fluid.

4. Allow time for oil to completely drain. While it is draining wipe the plugs clean. The lower plug is usually magnetic and will have metal attached(normal).

After draining is complete

1. Pump new fluid into bottom drain until fluid is running out of top plug at the same rate you are filling from the bottom.

2. When full replace the top plug.

3. Remove the filling tube/hose from the bottom and replace the magnetic plug at the bottom of the foot. Some fluid loss is expected but speed is important replacing the bottom plug.

There are o rings or gasket type seals on the plugs. You should replace these however they can normally be reused several times before being replaced. Be sure to inspect drained fluid for water. If water is present it will separate from the oil. If water is present you will need to replace shaft seals.

This is the condensed version, but the process is quite simple, and you will understand as he performs the steps. Hope this helps..........................Al

thanks AL, well explained.

my gaskets seem to be really old, where can i get new ones? and do they have to be a special kind?

timmy,

i guess they're special i told the guy at carquest what i wanted and he pulled out a book(same book he ordered my water pump out of) showed me a picture of 'em.  they come 2 in a pack.  few bucks i think.

BTW, check walmart, BPS or cabela's, most of them sell a pump assembly with a fitting that screws into the lower drain hole and allows you to pump the new fluid in making it much easier.  The cost is usually around $11-13 for the pump, hose and fitting. They make fittings for most of the major brands of OB's.