cd-21a couple ?s

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frank27

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Feb 9, 2011
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i've searched on the site and cant seem to find what im looking for i want to reseal my lower unit i have a few questions
#1 when putting a new seal in the gear case head do u just put the new one in or do u have to grease it or anything
#2when putting the gearcase cover back on i have a long skinny seal do i just use the seal or use the seal and a sealent
#3 when putting the lower unit back on do i use a sealent for that
thanks frank
 
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AlTn

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Re: cd-21a couple ?s

read the thread belonging to ccvolsdhf..he's recently done this and has excellent pics
1. best to put some sealant around the outside metal surface of the seal before seating it
2. That seal and sealant <3M 847 is what the local dealer uses > cut the spaghetti seal ~ 1/16" longer on each side so it'll touch the bearing head surface
3.No sealant between the lower unit and exhaust housing
 
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frank27

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Re: cd-21a couple ?s

good video i got a new bearing housin and gear head for next to nothin so i wont have to pull the old one out
 
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AlTn

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Re: cd-21a couple ?s

are you replacing the d/s seal under the water pump?...the shift rod seal < fat oring > that's at the base of the shift shaft bushing?
 
kfa4303

kfa4303

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Re: cd-21a couple ?s

Hi Frank. this link can walk you through a reseal job too. It's for an 18 hp, but many of the steps are very similar. You do want to use a bit sealant around each oil seal as well as the spaghetti seal you mentioned. I also put it on the outside of the propshaft bearing where it mates with the gear case. The sealant of choice is 3M 847. It's a little pricey, but very good stuff and a little goes a long way. A local dealer may have it, but you may also have to order it. I know a mechanic that also uses Permatex 1000 instead, which is more readily available at most auto parts stores and is less expensive. You do not and should not put any sealant on the lower unit itself. Here's the link.

http://forums.iboats.com/showthread.php?t=277190&highlight=lower+unit+seal+kit+installation
 
kfa4303

kfa4303

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Re: cd-21a couple ?s

cool. be careful with some of those smaller o-rings, they can be awfully small. A bit of vaseline on the top of the splines of the driveshaft will help the drive shaft o-ring slip on a bit more easily and should help reduce the chance of chaffing. A bit of vaseline on the top of the lower shift rod will also help it pass through the short, thick little o-ring used under the shift rod bushing which can sometimes be pretty tight. Also, don't be surprised if the old seals are a PITA to get out. I think we've all had the clip, snip, and twist them out in the past. Particularly if they've never been changed before. Good luck. Holler if you get stuck.
 
1946Zephyr

1946Zephyr

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Re: cd-21a couple ?s

Hahaha just did this same job last weekend. When you install the new shift rod o-ring, its best to put the shift rod in the gearcase, like it's supposed to go and slip the o-ring over the shift rod. Then carefully poke it down inside the pocket with a blunt object. If you install the o-ring and then poke the shift rod through, you have a good chance of damaging the o-ring. Use lots of oil on all your seals, when you mate them up with the parts they run on.
 
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