Re: 1982 4.5 merc lower unit help
The shift cam has been pushed out-of-position by the spring-loaded shift clutch. So it's in foward gear all the time.
To fix this, first have all the oil drained out of the gearcase.
Then, you'll need to remove the shift shaft bushing/seal assy. It's held in by the square-headed screw sticking sideways to the middle of the bushing.
Very Very carefully grab the shift bushing with a set of pliers or Vice Grips. Not too tight because you could crush the bushing. Then twist while pulling upwards, this should take the bushing right out. If it's reluctant to move, you'll have to apply heat to the outside of the gearcase in the area of the bushing, in order to expand the parts & get enough 'wiggle room' to loosen the bushing for removal.
Once you have that out, the next thing to do is to get the shift cam in the correct position.
To do this, turn the prop clockwise. You'll feel a slight resistance then it'll ratchet. If you leave the prop in the position just before it ratchets, you've removed the spring pressure off the shift cam.
Then you can wiggle the lower unit around while peering into the shift shaft hole, until you get the cam realigned. As soon as you see the center hole of the shift cam, get the shift shaft in there!
If the prop happens to move <click!> just reposition and try again. The shift cam will move around a bit but can't really go too far.
Keep in mind that there is a groove in the shift shaft, in this groove is supposed to be a clip which supposedly prevents the shift shaft from being removed. Unfortunately this clip is easily overpowered when the upper and lower shift shafts are stuck together.
Hopefully you'll be able to find the clip. Personally I wouldn't re-use it, instead find a "C" clip that fits the groove. It'll hold better. Be sure to clean up any burrs on the shift shaft that could tear up the seal.
If you can't find the clip and don't intend on tearing the lower unit apart to find it, I'd recommend getting a drain hole screw with attached magnet, just in case the clip is floating around. The magnet will capture the clip and keep it from possibly getting in the gears and being ground up into metal shards.
Note: if the shift bushing/seal assy is damaged, it's available as a unit. The shift shaft seal is available separately although it's a bit of a pain to change out.
Anyway, that should get you there. The only other alternative is to pull apart the lower unit. You'll need to purchase or make a tool to remove the threaded gearcase cover. After that, the 'guts' pull out easily.
If you have a 'Salty Dog', it's gonna come apart real hard and I wouldn't recommend doing so unless you had to. A freshwater motor won't have those issues so you might consider it if necessary.
HTH & G'luck with the repair......ed