Repeated driveshaft failures.

misery

Petty Officer 3rd Class
Joined
Jul 18, 2010
Messages
98
Hi folks. last season my 1986 evinrude 90 hp cut a driveshaft off just below the impeller. I found a used one and installed it and finished out my season. Well almost to the day, it just cut off its replacement shaft. I have another shaft but I am scared to put it in. The first time I just thought that it was age and fatigue, but now i am suspecting something more sinister. What could be causing this? Is there something i may have done wrong when reassembling the gearcase? thanks for everything.
 

JDusza

Ensign
Joined
Apr 21, 2009
Messages
934
Well, it is more sinister, that is true. It takes a lot of work energy to cut a drive shaft. We have to look at what is located right below the impeller, in that vicinity. Can you line up the pieces and determine what may be interfering with the shaft? Does the shaft look "cut" or "torn"? Right below the impeller are the seals and bearing, so, I would guess there is something wrong with the bearing that is cutting the shafts. Is the bearing housing seated properly?
Did something go wrong at reassembly of the gear case? I'm guessing "yes."
Check out an exploded view, like on marineengine.com, and see if you can relate the position of the break to one of the components of the drawing.
J

http://www.marineengine.com/parts/j...0MLCDC&manufacturer=Evinrude&section=Gearcase
 
Last edited:

JDusza

Ensign
Joined
Apr 21, 2009
Messages
934
Well, it is more sinister, that is true. It takes a lot of work energy to cut a drive shaft. We have to look at what is located right below the impeller, in that vicinity. Can you line up the pieces and determine what may be interfering with the shaft? Does the shaft look "cut" or "torn"? Right below the impeller are the seals and bearing, so, I would guess there is something wrong with the bearing that is cutting the shafts. Is the bearing housing seated properly?
Did something go wrong at reassembly of the gear case? I'm guessing "yes."
Try this link to guide you. http://www.marineengine.com/parts/j...0MLCDC&manufacturer=Evinrude&section=Gearcase
J
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
A bent gearcase or exhaust housing will cause the drive shaft to break so cleanly that you would swear it never was attached. The factory service manual explains how to check the parts for bending. It isn't easy.

BTW, don't think the parts are so hefty that they can't be bent. Believe me, they can.
 
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