Help remove a bearing carrier on '73 Mercury lower unit..

Colwell87

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Jul 9, 2013
Messages
11
Hey, I'm looking for some good input on what to do with my outboard. It's an 1973 Mercury 850. There is gear oil leaking from the lower unit.

The gears fill tight, no slop in them and it seemed to be shifting through its gears just fine. But I took it off the upper unit to figure out why it was leaking and to replace the impeller. Turns out the bearing underneath the impeller housing, on the input shaft is shot and I think that is where the oil is coming from, the seal above that was in pretty bad shape also. So, according to my service manual the output shaft has to come out in order to loosen a nut on the input shaft to get that to come out.

I ended up having to cut my cover nut out because it was stuck, it wouldn't budge any direction with any tool for any reason. I tried heat, lubricant and made sure the tab was out of the way.

After cutting the cover nut out I was able to get a slide hammer on the bearing carrier. And that's as far as I am. I've heated it, lubricated it, waited for it to cool, and just about everything else I know of and it wont come out.

Before doing all of this I did inspect it and noticed a few odd things, first it is cracked on two of the wings, maybe from the previous owner trying to fix the oil leak? Also, the threading on the lower unit is odd, it stars out one size and than changes to a smaller size about half an inch in, is this normal?

How would you guys recommend going about getting the bearing changed? Thanks for your help!
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,638
Your are proceeding as the service manual recommends. I ended up using a puller on the bearing carrier, and beating the puller with a BFH (hammer). You are sure the driveshaft bearing is bad? The waterpump base seal is easy to replace.
 

merc850

Commander
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Jul 7, 2010
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2,055
I had the same problem; a puller can be attached to the bearing carrier, tighten it then keep penetrating oil in the exhaust outlet. Heat will also help, the threading is normal but don't break the edge of the LU housing.
 

Colwell87

Cadet
Joined
Jul 9, 2013
Messages
11
Thanks for your responses, guys!

Am I 100% sure the bearing is bad? Well, its not in terrible shape, I went ahead and cleaned it and it seems alright, but the whole drive/input shaft has about half an inch movement straight up and down, when its pulled up, there is a fair bit of side slop, is this normal? If so, I think I might get a new nut, seal kit and put it all back together. The only concern I have with just putting it all back together is the cracks on the bearing carrier. The carrier is still pretty solid in there but who knows...

merc850, the edge on the LU housing is okay right now, there are two minimal cracks that I think I had caused when getting the cover nut out. They are about an eighth of an inch long each, I think they can be fixed with a little epoxy or some sort of metal repair compound.

Anyways, thanks for taking the time to help and read my long post!
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,638
Does your driveshaft have a preload pin on the end? Merc used different kinds of cone bearings on their driveshafts. Some needed preloading, some didn't.
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
Items 10 and 11 are the pre-load pin and spring. Fits into the motor end of the shaft.
 

Colwell87

Cadet
Joined
Jul 9, 2013
Messages
11
So I looked at the shaft and it does appear to have a preloading pin, so that begs the question: what is it for?

Also, looking more into it it seems the bearing is in okay shape, the leak is coming from the base seal(below the water pump) and the reason the seal is bad is because the drive shaft is corroded where the seal comes into contact, so I'm starting to wonder if I should cut my losses on this lower unit and search for another in better shape.

Any one have any thoughts up to this points? Thanks!
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,638
I would clean the driveshaft with sandpaper and then lube it up. Now install a new waterpump base (w/ a new seal) and gasket and Oring. Install an impeller, wearplate and two gaskets and the waterpump cover and slinger. Refill with gearoil and retest. Since you cut out the bearing carrier nut, you might like to install a rivet or two to hold the bearing carrier in, should the gearcase be serviceable.
 
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