Cracked Lower Unit near nose cone (see pict)

[green heron]

I read the forums about cracked lower units, but most people had cracks above the prop. My gear casing ('73 Johnson 115 HP) is cracked around the nose cone. The crack is spreading around the nose cone as shown in the picture link below. The motor runs and shifts into gear. Is this fixable, and if so, I'm wondering if I should use the technique mentioned in previous posts and drill the ends of the cracks and JB Weld the entire area.<br /><br />Any advise is appreciated.<br /><br />

 

[OBJ]

Re: Cracked Lower Unit near nose cone (see pict)

Welcome green heron!<br /><br />I believe for a crack like that, I would find a good welder that can tieg or mieg weld the crack. What was the crack caused from and is it into the machined area inside where the shift pump sets?

 

[green heron]

Re: Cracked Lower Unit near nose cone (see pict)

I'm unsure what caused the crack since the Johnson 115 came with the Mako 19' boat I just purchased. I didn't pay much for the boat and didn't expect much of the motor - except it runs great and I'd like to keep it for a while. The lower "skeg" section has a large chunk of metal missing, probably from running aground or into a rock. This may have caused the crack. I haven't taken the shift pump out, so I'm not sure if it's into the machined area. On these old Johnsons, do you know how much of the nose cone is bored out, and does this section retain any of the lower unit's oil?<br /><br />The one thing I liked about the JB Weld option is that it would reduce the time of repair. I need to get the boat on its mooring in two weeks (otherwise it goes to the next person on the list)! Do you think this could last through the season?<br /><br />I appreciate your help!

 

[DJ]

Re: Cracked Lower Unit near nose cone (see pict)

You have nothing to lose by JB Welding it. Make sure the L/U has been drained, before you make repair attempt. <br /><br />I'm not even sure I would drill it since you do not know what is behind it.

 

[green heron]

Re: Cracked Lower Unit near nose cone (see pict)

I'm concerned that if I don't drill the endings of the crack, it will continue to grow past the JB Weld area. Does anyone know the thickness of the casing so I can set a stop before drilling through?

 

[dakotarmx]

Re: Cracked Lower Unit near nose cone (see pict)

green heron im new to the whole boat world but i have j b welded side cases on two dirt bikes .id give it a shot .id drill the ends out with the smallest bit you got .

 

[Texasmark]

Re: Cracked Lower Unit near nose cone (see pict)

As long as the bit is larger than the crack.<br /><br />Guessing thickness is 1/8". Put a stop on your drill bit.....anything that you can slide over the bit to stop it from going down into the housing when it punches through....(socket from a wrench set would work)<br /><br />Inside is nothing but oil and parts harder than the aluminum. No seals there so I wouldn't worry too much about punching through. Also go slowly and try to retrieve all your shavings.<br /><br />Might purge with oil (like you were filling the sump) when finished to wash out any that may linger.<br /><br />Then drain and be sure and rough up the housing and apply a good degreaser prior to JBing. I like to use automotive brake cleaner. It has pressure and the right chemicals that wash out the grease/oil etc, yet doesn't attack paint (like chemtool carb cleaner), and dries fast without residue.<br /><br />Good luck.<br /><br />Mark

 

[dakotarmx]

Re: Cracked Lower Unit near nose cone (see pict)

yep yep sounds like a plan good luck green heron

 

[green heron]

Re: Cracked Lower Unit near nose cone (see pict)

I successfully drilled out both crack endings, sanded, cleaned the area, and then JB welded the entire area with multiple coats. It looks great! Then the wind was really taken out of my sails when after filling up the lower unit with oil, I noticed a steady oil leak from the propeller shaft! It seems unrelated to the crack in the nose cone. Fast forward to Plan B.<br /><br />Plan B: <br /><br />I ordered a used replacement lower unit in better shape and an OMC manual. This will be my first attempt at replacing a lower unit. Can anyone tell me (best case/worst case) how long it should take?<br /><br />Thanks.

 

[dakotarmx]

Re: Cracked Lower Unit near nose cone (see pict)

ouch .that bites