70HP lower unit seal replace?

My 1984 Johnson appears to be leaking oil from the gearcase. I noticed some black oil sliding down on the back of the prop from the lower unit after running it with muffins at the house. Next day I noticed about 2 ounces of tan oily yuck under the prop on the driveway. I tried to drain the remaining oil to check the lower unit and about 6 ounces of water (clear) came out...no oil. I pushed in about 20 ounces of oil and it needs more. My guess is it was empty and I am lucky it didn't blow out. After replacing the oil, nothing else has leaked, but I haven't run it either. Anyhow, I'm thinking the seal at the prop is bad...could be more (what do you think). How difficult is it to replace that seal? Special tools or car mechanic stuff?

Re: 70HP lower unit seal replace?

I filled the lower unit with oil...about 31 ounces so it was empty. I can't imagine that it was running fine without oil, but.... I will start it up soon and would prefer a real water test--not muffins--but the weathers been yuck and time isn't on my side. The good news, I suppose, is that after I filled the gear case (haven't run it) there is no sign of leakage and it's been about a week. Then again, there hasn't been any pressure.

Re: 70HP lower unit seal replace?

Muffs.

I got a mechanic to replace my seal on a 70 and it wasn't very expensive.

Re: 70HP lower unit seal replace?

Shouldn't be to hard, you can buy a seal remover (its been awhile, but $15 or so) or if your careful you can use a screw driver, use it as a pry bar between the rubber of the seal and prop shaft, push down a little at a time and work it around the inside of the seal. If you use your engine in salt water take your time and go around several times. If you use a seal remover tool be careful again the edges are VERY sharp and can cut yourself or put a hole in the metal part of the seal, no big deal about the hole just keep trying, be genital. What I've done is file the edges flat on the seal remover, this helps to stop putting holes in the seals metal outer rim and makes it a bit easier to remove it. Be careful no to damage the the surrounding aluminum.