73 Evinrude 50 hp Lower Unit Repair

[sray]

After giving up on obtaining a used lower unit I have undertaken the disassembly of the damaged one. I have gotten to the point where the driveshaft and pinion must come out to remove the gear and shift mechanism. The unit set dry for some time due to the case freezing and cracking. All shafts and gears so far are smooth and crisp but bearings/seals are shot. I have removed the four bolts and the top bearing plate on the driveshaft and can turn it a little and it moves up and down about 1/4", but will not pull out. The information I have shows a set screw, but the one I have removed doesn't seem to help. It was in the water intake area. <br /><br />What do I do to remove the driveshaft? The shift mechanism is also stuck won't move up or down. The prop shaft will turn and the pinion is not engaged.<br />Thanks

 

[Skyhigh]

Re: 73 Evinrude 50 hp Lower Unit Repair

You must remove the pinion nut. <br /><br />Special tool OMC No. 311875 is required to turn the driveshaft in order to remove the pinion gear Nut.<br /><br />If the special tool is not available, clamp the driveshaft in a vise equipped with soft jaws, in a area below the splines but not in the water pump impeller area. With the proper size wrench on the pinion gear nut, rotate the complete lower unit COUNTERCLOCWISE....

 

[OBJ]

Re: 73 Evinrude 50 hp Lower Unit Repair

Sray....the little screw near the water intake holds the lower drive shaft bearing race in place.<br /><br />You must remove the pinion nut and then the pinion gear before the driveshaft will come out.

 

[sray]

Re: 73 Evinrude 50 hp Lower Unit Repair

Thanks for the help. The driveshaft won't rotate. So the nut can't come off by holding it and turning the shaft. I sure can't see how that set screw would hit a bearing, it seems so far from the centerline of the shaft. I have put quite a bit of rotating force on the drive shaft to try and turn it and it's froze, it will move up and down slightly. <br />Any other suggestions?<br />This has got to be better than any manual. I have a generic Evinrude manual, it doesn't show the problems you might incounter.

 

[Skyhigh]

Re: 73 Evinrude 50 hp Lower Unit Repair

Have you removed the water pump and the seal housing?

 

[sray]

Re: 73 Evinrude 50 hp Lower Unit Repair

Yes, i[ve removed the fou bolts and the top Bearing and seal assembly. I can see where the shaft get considerably larger. The shaft will shake form side to side at this point and move up and down.

 

[sray]

Re: 73 Evinrude 50 hp Lower Unit Repair

Where'd all my great help go, we were on a roll. It can't be so late that you've given up for the evening. I'd still like to know what is holding that shaft from turning or how much force it will stand to turn it without damage.<br />Thanks

 

[OBJ]

Re: 73 Evinrude 50 hp Lower Unit Repair

Sray...if the driveshaft moves up and down and side to side....it should turn unless somethind is binding the pinion gear or the driveshaft bearings are chewed up into the drive shaft. The bearing race set screw sets in ontop of the race. Weird I know....but thats' how it is.<br /><br />I would try and get a box end wrench on the pinion nut and try to losen it. It must come of if the drive shaft is to be removed. If you don't have special tools or a soft jawed vise, you can use a pipe wrench (somebodies going to say something about this) on the part of the drive shaft that doesn't have splines or have a sealing surface. Any marks can be cleaned up later with a file.

 

[The Marine Doctor]

Re: 73 Evinrude 50 hp Lower Unit Repair

For shame...the dreaded Pipe Wrench.<br /><br />If its done carefully..its should be fine...just try not to let it slip.<br /><br />You could though...try a vice grip farther down the shaft.<br /><br />Also...take note it was mentioned that it will not shift either...I would think there is some gear damage done and that is preventing the shaft from turning.<br /><br />TMD

 

[OBJ]

Re: 73 Evinrude 50 hp Lower Unit Repair

I'm all a'shamed

 

[sray]

Re: 73 Evinrude 50 hp Lower Unit Repair

Thanks for everyones help. I still can't believe the knowledge that's available on this site.<br /><br />Guess it proves that "not one of us is as smart as all of us".<br /><br />I'll put the suggestions to use today and let everyone know how it works out.<br />Thanks again.