Lower unit fluid change.

[cbull37]

Whats the right way to change the lower unit fluid on a 1987 Johnson 30 hp? How much fluid oz should it hold?

Thanks for the help!

cbull37

 

[Carusoswi]

Re: Lower unit fluid change.

Should be the same as for my two motors ('74 Evinrude 9.9 and '93 Johnson 25 HP). Back out the two "screws" that plug the fill and drain holes on the lower unit. Take out the top plug first, have a catch pan ready before you take out the lower plug. Allow the old lube to drain into the catch pan. Buy a lube kit (probably want to do this first, LOL). In addition to the lube, it will include a plastic tube with a silicon fitting, that you screw into the lower of the two holes on your lower drive unit, attached to a pump that you attach to the bottle of lube. Screw that silicon fitting into the lower hole, and pump lube into the lower hole until it begins to flow from the upper hole.

Replace the screw type plug into the upper hole, then remove the silicon fitting from the lower hole and replace that screw type plug . . . you are good to go.

The reason you fill from the bottom is to eliminate air from the system.

It's really more simple than it sounds.

As you drain out the old lube, observe its color. If it's old, it should be dark in color. If you see a milky color, your lower unit might be leaking water during use (I have this problem with one of my motors due to a cracked plug).

Good luck.

Caruso

 

[Mercury13]

Re: Lower unit fluid change.

If you have a manual look up the capacity, it isn't much. My Honda 15 takes less than half a quart.
I squeeze it in the botton through a gear oil bottle 1 qt. The nozzle fits in there nice. Everything else like Caruso said.

Steve

 

[ezeke]

Re: Lower unit fluid change.

Capacity is 11 ounces.

The main reason to stop filling when oil runs out the top hole is so that you don't overfill and blow the seals when the gearcase heats up.

 

[Al-53]

Re: Lower unit fluid change.

Also make sure you use new drain plug gaskets....using the old ones may let water into the lower end ..they are a 1 time use gasket using a compression seal....they are less than a dollar at a outboard shop...

Al