FD-15 lower unit
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- This topic has 15 replies, 11 voices, and was last updated 7 years, 9 months ago by donsmarine.
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June 4, 2016 at 4:04 pm #4432
Changing the seal on the driveshaft. There were two seals. First one was in normal, the top one put in upside down. The kit calls for one seal and the part list calls for one. Any reason why there were two? There is room for both. Baffled and confused. 1961 18 hp Johnson.
June 4, 2016 at 4:25 pm #37683Well someone was probably just trying to use a dual seal set up like found on later model engines. The outer seal’s lip faces out, meant to keep water from being pulled inside the gearcase. The inner/lower seal’s lip faces down to keep gear lube from leaking out.
June 4, 2016 at 5:41 pm #37684Sounds reasonable. But the driveshaft now has a groove where the seal lip is. The lower unit passes the air pressure test of five pounds for 15 minutes but still seems to get water in it. I’m thinking that the next thing is to replace the driveshaft. Thoughts?
June 4, 2016 at 5:55 pm #37685I am thinking speedy sleeve to cover the groove worn in the drive shaft.
June 4, 2016 at 5:57 pm #37686Not familiar with that. What is it?
June 4, 2016 at 6:42 pm #37687Speedy Sleeve is a thin stainless steel sleeve that goes over the worn area. They aren’t cheap. Neither is a drive shaft. How about the shift rod seal? And of course there are other places too, like the spagetti seal, etc, etc. How bad is it leaking anyway? You might consider a few extra oil changes if we are talking drops.
June 4, 2016 at 6:48 pm #37688Frank, thanks for the response. The other seals are good. Under pressure, the driveshaft seal did leak originally. I pulled the two seals that someone had put in. Evidently it must have leaked in the past. Time to figure out how much to put in it.
June 4, 2016 at 7:43 pm #37690Aggreed,If you haven’t already changed it, the shift rod seal [o ring] is most likely the culprit…. very common to leak on most 50’s and 60’s OMC outboards. Easy to change with the correct tools. When you have the lowerunit pressurized, try wiggling the shift shaft around a bit to see if it leaks while shifting in and out of gear.
June 4, 2016 at 7:54 pm #37692Did you shift it, wiggle shift shaft and drive shaft, turn drive shaft while doing the pressure test?
June 4, 2016 at 7:59 pm #37693Yep, did all of the above. Replaced many of them, have a couple dozen o-rings in the parts drawer. OEM rings. I use the Stevens pump for pressure testing. I even have Frank’s special tool! Thanks once again Frank!!
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