Re: Bearing Carrier Question
It doesn't appear to use a ball bearing for the reverse gear. This is a newer-style bearing carrier with integral thrust surface for the bearing, and I'm assuming the reverse gear rides directly on the aluminum i.d. of the carrier.
I wouldn't think this would be as durable as a ball bearing, however, I expect Merc did the engineering to prove that gear oil would adequately lubricate this hardened-steel bearing riding on bare aluminum! Maybe it's even stronger than the ball bearing, who knows!
There's not quite as much stress on the reverse gear, anyway, since you're not usually going full throttle in reverse! Forward gear has a proper tapered roller bearing, with bearing race pressed into the front end of the gearcase.
This exploded parts diagram clearly shows a lack of reverse gear ball bearing:
Mercury Marine 140 HP GEAR HOUSING ASSEMBLY, COMPLETE (PAGE 2) Parts
At any rate, I don't think you have any issues there. But you are missing a thrust ring which goes against the square shoulder of the gearcase. The O-ring on the machined lip of the bearing carrier seats up against this ring. Or maybe you have it, it's just not in the picture. The flat side of the ring faces the front of the gearcase, and the other side, which has a contour/bevel in it, faces the O-ring.
You'll want to renew the O-ring as well. When you reassemble the lower unit, coat the O.D. of the bearing carrier, where it will contact the i.d. of the gearcase, with Permatex No. 3 Aviation-type brush-on gasket dressing. This keeps salt and other nasty corrosion products from getting into the joint and seizing the bearing carrier into the gearcase. Or, in extreme cases, cracking the gearcase.
Renew the 2 propshaft seals and check the propshaft needle bearing for roughness/corrosion/cleanliness.
Note that there's a teeny weeny key that locates the bearing carrier; very easy to overlook and wouldn't be a good thing to leave out! P/N 67 on the diagram. If you look carefully, you'll see the notch in the i.d. of the gearcase where the key sits. Sometimes, if there's a lot of corrosion buildup, the key will stick in its groove in the carrier; and junk/gunk builds up in the gearcase notch, making it easy to miss. Scrape clean the gearcase & carrier so the key will fit properly. If you slather some Permatex No. 3 in the groove in the carrier, it'll help hold the key in place and keep corrosion from building up around the key.
The gearcase locknut (aka gearcase "cover") requires a special tool to turn it; and it takes a ton of torque to properly tighten. If you're handy with fabrication, you should be able to make a satisfactory locknut tool, otherwise there are factory and aftermarket tools available. I'd expect your manual has a good pic of the tool.
HTH & G'luck with the reassembly.........ed
