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Discussion Starter · #1 ·
83 25hp merc tiller

works fine in forward any rpm
works fine in low rpm reverse
when giving any significant gas to reverse it sounds like the hub is spun plus a little clanking sound.

thoughts?

thks

Alex V
 

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Discussion Starter · #4 ·
No recent service. It just started doing it about a week ago or so. I like the idea of the rounded clutch dog ears, makes sense for the current symptoms. I've subsequently started the tear down process. First prob was a fair amount of water in the foot oil (bolstering the need for the rest of the tear down for seal replacement if nothing else). The prop was stuck on the splined prop shaft necessitating cutting the prop off with a saw (oh so fun). Yes, I tried heat, penetrating oil, hammer taps, sailor-grade cursing etc. Now I can't seem to get the rear bearing carrier off easily. Looks like it takes a special wrench? Also, any idea on how to pull the shift rod's shift shaft retainer? Not sure if it pries off? I'm getting that sinking feeling...
Thks
Alex
 

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Lower unit tear down and repair requires special tools and IMHO not a job for the normal guy.

Might look for a marine trade school to do it as a project.

Good luck.
 

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Discussion Starter · #8 ·
You guys are acting like a bunch of wusses. Especially with all the home repair stuff I see you posting. If you're just gonna tell me to get a refurb then let's have some fun with this one (and learn something).
I finally managed to get the rear bearing carrier off with a three screwdriver technique. I'd tell you a little more about it but I'm waiting to hear back from the [*******] patent office. Didn't even require the high level profanity that the prop removal did. Just a little low level stuff under my breath. The wife was much appreciative as the kids are still asking questions about the last "episode." Inspection of the reverse and forward gears and the clutch dog showed what I would consider is minor (expected for an '83?) wear. The wear was even across all the gears/dog also (and not worse on the reverse to help diagnose the original prob). Call me silly but I would guess they would make the metal of the clutch dog a little softer than the gears so that it would wear or break before them. But then again I'm not in the business of selling replacement parts, am I? I pulled the drive shaft and it and the pinion gear look good. There are roller bearings for the forward/reverse/pinion gear and a thrust bearing for the pinion gear that feel nice and smooth as well. The clutch dog spring has plenty of force (could it be the problem?). Would be easy to replace if so I guess. I ordered a lower unit seal kit off eBay after checking the part numbers like 15 times. Those superseded part numbers always worry me. It came on Friday and seems to have all the stuff. Also ordered a water pump kit. The seal kit and water pump kit have stuff that overlap but not enough to do both jobs with one kit.
I still can't get the shift shaft retainer off. I've tried prying, pulling, and twisting. Not sure if I don't have my mouth just right or just don't have a big enough hammer. It's part number 24 on the parts diagram:
http://www.marineengine.com/parts/mercury-outboard-parts/25-2-cyl/5705532-thru-6416712-usa/gear-housing-drive-shaft
It's the piece that holds in the shift shaft in that you see when you drop the foot for a water pump change (it's under the rubber boot). I'd like to inspect it and change the seals there also. Any help appreciated.
I'll post some pictures at some point.
Btw, it was pretty neat seeing the lower drain screw from the inside. At first I thought it was something bent as it comes in from an angle (ha).
Also, if you ever do this, watch out when you pull the spindle shaft out with the gears. There's gonna be a little oil in there still, even if you drain it well. And that oil will always find its way to the top of your shoe...cover your ears kids.
 

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I damaged a prop shaft on my old 03 Merc 25. I was really not looking forward to opening up the gear case, but it wasn't a big deal after all. I used a lathe to resurface an area of the shaft and added shims to get the proper clearances. The cost was only for one bearing, seal and a couple of shims. I even straightened the prop shaft back perfectly while it was chucked up in the lathe. I used it for a few years after the repair and it held up great. A crab trap tangled around a gear case and prop is very destructive!
 
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