stuck drive shaft on 1959 mark 55 40 hp

[tiger 650]

I just bought an old Mercury outboard . The motor was put up in storage with water in the gearcase. I pulled off the gearcase, I have removed the prop shaft and found the bearings are ruined from rust. I have removed the bolt that holds on the small gear inside the case. The gear is loose and wiggles. I have removed the water pump nut and removed the impeller. The body of the pump will not come out. It doesnt apper to be rusty. I need to pull the driveshaft out to get to the seal and bearings in there. The shaft is stuck. It will spin but just wont come out. I have held the unit by the shaft and whacked it with a rubber mallet and it wont budge. There is either a fastener that I cant see or the bearing is held in by rust. Help!

 

[Texasmark]

Re: stuck drive shaft on 1959 mark 55 40 hp

I just looked at an exploded view of the lower unit for my Merc which is higher hp and later model than yours. But a lot of things don't change especially if they functionally work. On mine, starting from the bottom of the drive shaft is a nut then the pinion gear then the bearing that the pinion rides in and supports the lower end of the drive shaft then nothing on the shaft till you get right under the water pump where the carrier bearing and oil seals are.

So, if you removed the nut and the pinion gear from the bottom of the shaft there should be nothing deliberately holding the shaft in the housing and you should be able to pull it out. The pinion gear and locking nut are what holds the shaft in place in normal operation. The lateral thrust from the gear meshing is transmitted to the pinion which is sitting in it's roller bearing race which is what keeps it from lifting up from the thrust.

Good luck,

Mark

 

[Chinewalker]

Re: stuck drive shaft on 1959 mark 55 40 hp

If you have the nut off the end of the driveshaft, then all that's holding things in place is friction. The ball bearing just below the waterpump cup is a press fit and there is a lip on the driveshaft just below the bearing that prevents the shaft from pulling out on its own - so, you need to pull the cup & bearing out with the shaft. You can brute force it out, but things go much easier with some heat. Using a propane torch, heat the housing just below the waterpump cup, where the bearing is. Heat both sides as evenly as you can. Then, with the driveshaft in a vice (use wooden pads to prevent marring the shaft) and a block of wood on the face of the housing, tape the housing away from the shaft. The shaft/cup/bearing SHOULD pull out with gentle tapping on the housing. Do not bash away willy-nilly on the housing as things can crack if you're too forceful. The heated aluminum housing expands away from the steel of the bearing, making things come apart easier. Heat helps remove the forward gear/bearing assembly, too....

 

[tiger 650]

Re: stuck drive shaft on 1959 mark 55 40 hp

The shaft is out. I soaked it with Liquid Wrench overnite and 10 minutes ago I clamped the shaft in a vise, heated the case with my B&D electric paint stripper and put a block of wood against the case and tapped the shaft out. Thanks for the help. Tiger650

 

[Texasmark]

Re: stuck drive shaft on 1959 mark 55 40 hp

The shaft is out. I soaked it with Liquid Wrench overnite and 10 minutes ago I clamped the shaft in a vise, heated the case with my B&D electric paint stripper and put a block of wood against the case and tapped the shaft out. Thanks for the help. Tiger650

Great. Hope things go smoothly from here for you.

Mark