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Author Topic:   Split gear-case housing on older Fastwins

Sojo81007 posted 08-20-2011 11:01 PM ET (US)
I have the original 18hp Fastwin that I believe came with my little Whaler. It runs great except for water in the LU...Water appears to be running out of the seam in the gear-case portion of the LU (as you know, these LU are two pieces and the gears can be accessed by removing 6 screws.)
I ordered a new spaghetti seal because I assumed that water should not be running out of that seam when I pull it from the water. My question is can I open that case and replace the seal without causing harm? I heard that there are shim/bushings which have to be set just right. I have a 1947 14hp Johnson with a similar (looks identical, actually) lower unit and I opened it. Looks like I just set a new gasket in there with permatex or something and then simply put it back together. Am I missing something? I have a manual but it says "if there is water in your lower unit please contact a certified marine mechanic." ha!
:) I'm nervous about doing all the seals on the LU. It's not worth paying someone else to do it...I did toy with the ID of doing the old 47 as a practice run...and then, if they truly are compatible, I'd have a spare LU for the motor.
Tohsgib posted 08-21-2011 12:11 AM ET (US)
I would not sweat it.
Binkster posted 08-21-2011 08:03 AM ET (US)
Actually a very simple job unless the 6 screws are corroded from salt water. Clamp the gearcase in a vice upside down, remove the 6 screws and the one small one in the base of the skeg that holds the shift yoke, and just lift the bottom off. Use some grease to hold the new spaghetti gasket in place. I haven't fooled with these gearcases in a while but I think there is another seal at or near the prop end. I have taken these gearcases apart when I was 16 years old, back in the day they are very simple.
adlert posted 08-22-2011 09:28 AM ET (US)
As Binkster and Nick have noted, this is not a very tough job. I often find it helpful to use an impact driver to loosen the 6 screws. It is also needed occaisionally for loosening the philips head screw (on side of skeg) securing the yoke as Binkster mentioned. To do this job properly you should of course replace all 4 of the gearcase seals (spaghetti, prop shaft, drive shaft, shift shaft). With a good manual and care, you can do this fairly easily. The one sticking point will be your need for a highly specialized tool to remove the shift shaft o ring. I own this tool and can loan it to you if you promise to return it!
If water is leaking out of the lower unit you may already have significant bearing damage. I strongly recommend lifting the entire prop shaft assembly out once you split the gearcase and then separating all the parts on a clean surface for a good inspection. It literally just lifts out. Talk to me if indeed you've got some damaged pieces. It is possible I have some usable spares available that I have no use for.
conch posted 08-22-2011 06:27 PM ET (US)
No shims that I recall but there are several(3) thrust washers.
This should be easy,use the impact tool and maybe some heat.
All the seals are in a kit online at IBoats for about 15 dollars.
Notice that the pivot pin (philips head screw in skeg)has its own seal
Parts diagrams are online at boats.net
I use a liquid brush-on sealant for the spaghetti seal and the mating surfaces.
If the clutch dog or cradle are worn they can be reversed which puts the worn side towards reverse gear which is used less often and at lower speed.
Take care not to lose the small dowel locating pin at the gear case head seal.
Usually it is just the seal at the prop shaft torn from fishing line.
Chuck

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Author	Topic: Split gear-case housing on older Fastwins
Sojo81007	posted 08-20-2011 11:01 PM ET (US) I have the original 18hp Fastwin that I believe came with my little Whaler. It runs great except for water in the LU...Water appears to be running out of the seam in the gear-case portion of the LU (as you know, these LU are two pieces and the gears can be accessed by removing 6 screws.) I ordered a new spaghetti seal because I assumed that water should not be running out of that seam when I pull it from the water. My question is can I open that case and replace the seal without causing harm? I heard that there are shim/bushings which have to be set just right. I have a 1947 14hp Johnson with a similar (looks identical, actually) lower unit and I opened it. Looks like I just set a new gasket in there with permatex or something and then simply put it back together. Am I missing something? I have a manual but it says "if there is water in your lower unit please contact a certified marine mechanic." ha! :) I'm nervous about doing all the seals on the LU. It's not worth paying someone else to do it...I did toy with the ID of doing the old 47 as a practice run...and then, if they truly are compatible, I'd have a spare LU for the motor.
Tohsgib	posted 08-21-2011 12:11 AM ET (US) I would not sweat it.
Binkster	posted 08-21-2011 08:03 AM ET (US) Actually a very simple job unless the 6 screws are corroded from salt water. Clamp the gearcase in a vice upside down, remove the 6 screws and the one small one in the base of the skeg that holds the shift yoke, and just lift the bottom off. Use some grease to hold the new spaghetti gasket in place. I haven't fooled with these gearcases in a while but I think there is another seal at or near the prop end. I have taken these gearcases apart when I was 16 years old, back in the day they are very simple.
adlert	posted 08-22-2011 09:28 AM ET (US) As Binkster and Nick have noted, this is not a very tough job. I often find it helpful to use an impact driver to loosen the 6 screws. It is also needed occaisionally for loosening the philips head screw (on side of skeg) securing the yoke as Binkster mentioned. To do this job properly you should of course replace all 4 of the gearcase seals (spaghetti, prop shaft, drive shaft, shift shaft). With a good manual and care, you can do this fairly easily. The one sticking point will be your need for a highly specialized tool to remove the shift shaft o ring. I own this tool and can loan it to you if you promise to return it! If water is leaking out of the lower unit you may already have significant bearing damage. I strongly recommend lifting the entire prop shaft assembly out once you split the gearcase and then separating all the parts on a clean surface for a good inspection. It literally just lifts out. Talk to me if indeed you've got some damaged pieces. It is possible I have some usable spares available that I have no use for.
conch	posted 08-22-2011 06:27 PM ET (US) No shims that I recall but there are several(3) thrust washers. This should be easy,use the impact tool and maybe some heat. All the seals are in a kit online at IBoats for about 15 dollars. Notice that the pivot pin (philips head screw in skeg)has its own seal Parts diagrams are online at boats.net I use a liquid brush-on sealant for the spaghetti seal and the mating surfaces. If the clutch dog or cradle are worn they can be reversed which puts the worn side towards reverse gear which is used less often and at lower speed. Take care not to lose the small dowel locating pin at the gear case head seal. Usually it is just the seal at the prop shaft torn from fishing line. Chuck