View Full Version : Changing lower unit oil...

09-30-2005, 08:04 PM
Time for more maintenance...

I bought this kit to change the lower unit oil. It a quart of oil and a pump. The directions say to drain first by removing the lower plug and then the upper plug. Once dained put back the upper plug and pump the oil into the bottom plug hole. Then immediatly put the plug back in.

I have a 48 Johnson 2 stroke. Hopw much oil should be put in? The whole quart? More Less? Any other tips?

09-30-2005, 08:21 PM
HI, been awhile since I change out lower unit oil, been running a jet unit for 7 yrs, but I believe the upper hole is left open till oil runs out of it as you put oil in the bottom hole. So the upper hole is the oil level hole and also the air vent when draining old oil. Confirm with a few more guys before you do it just to make sure.

09-30-2005, 08:34 PM
yes leave top plug out! fill from bottom until oil comes out top .

09-30-2005, 08:46 PM
That's the way I do it too, filling from the bottom top plug out till oil runs out then put it back in.

09-30-2005, 08:49 PM
Well i do see that in the directions as well. *So I get it now the top plug wont come out. *Its a flathead screw. *If I horse on it any more its gonna strip. *Tried 2 huge drivers and a drill with screwdriver bit. *Something sooo simple is now so hard...

Its too recessed to get vice grips on.

09-30-2005, 08:53 PM
I think if you don't get the top plug out you will have an air pocket and it will not get filled all the way.

09-30-2005, 09:23 PM
This was a fun article with lots of suggestions for me I think I may try some. Just thought I'd share...


09-30-2005, 10:12 PM
I would not use an impact screw driver on a lower unit. The screw is nice hard steel and the lower unit is soft aluminum. You could damage the lower unit.

The way I remove suborn drain screws is with a large screw driver with a square shaft. I hold the screw driver in the slot with one hand and use an open end wrench to turn the screw driver shaft with the other hand.

I once had to resort to heating the area with a blow torch. It didn't take much heat to loosen the screw, but I had to re-paint the lower unit.

09-30-2005, 10:30 PM
I dont wanna break anything before pyramid so I am gunna wait unit after to force it any further.

10-01-2005, 06:27 AM
Go in the tight direction first just enough to get a little movment then then try loosing the screw...use this in addition to Doc's method + a little penatrating oil you should be home free. GOOD LUCK ;)

10-01-2005, 08:51 AM
Thanks for adding that wetdog. That trick works particularly well for steel on aluminum parts.

10-01-2005, 10:01 AM
Already tried all that and tapping it in both directions with a punch. I am gonna get some penentrating stuff and try it all again.

10-01-2005, 05:29 PM
My first thought was to use an impact screwdriver (gently). *Although, I read doc's advice regarding that, which makes a lot of sense. You could damage the lower unit if you apply too much force. Aluminum does tend to fracture when whacked upon. If you do resort to using one, use a very good quality one. You are welcome to mine if you are close enough to pick it up.

Can you get a dremmel tool with a cutting wheel on the screw to clean up the screwdriver slot so you can get a little more muscle on it without stripping?

May I reccomend, after you do get it out, put anti-seeze on the threads before putting it back in. I have been using that on threads for as long as I can remember. Never had a problem since.

10-01-2005, 05:57 PM
Get out the hammer type impact screwdriver and remove the screw.

Just make sure the bit fits as well as it can, and that it has a freshly ground square and crisp edge to grab what's left.

10-01-2005, 10:21 PM
We use a trick on aircraft that sometimes works. After cleaning up the slot, ensure that the screw driver bit is "square", use a screw driver that you can increase your force with a wrench, and dip the tip of the screw driver in boraxo or comet cleaner. The cleaner adheres to the screw driver and provides a little more "bite". A little heat never hurt either. If you have one, A heat gun is preferable over a torch. Mistakes are way too costly and easy to make.

12-19-2005, 06:47 PM
You may have already succeeded in getting the screw out but if not, I had the same problem. I tried getting the largest head screwdriver I could find but to no avail. I respect what Doc said, he knows a lot, but I finally resorted to the impact screwdriver. I barely touched it with the hammer and the screw popped loose. That thing works really well. I would consider this a viable option if you don't need to stike it too hard.

I live in the south sac area if you would like to borrow it.