Cross thread 3.0 Merc prop shaft

[1960vw]

I took my prop off of my '93 I/O 3.0 Merc as regular maintenance. Sadly , The nut began to crossthread putting it back on and now I'm stuck. Can I use a die to clean it up ? What size do I use? Should I let a shop do it to make sure it's done right?

 

[ricovw]

Re: Cross thread 3.0 Merc prop shaft

I am a machinist by trade, and if you don't know what you are doing, you can make a real mess of things pretty quick. From your post, I can't determine if it's the nut you stripped, the shaft or both. I cant give any tips until that is determined. At this point, things may still be save able, so the next step is very important.

 

[picklenjim]

Re: Cross thread 3.0 Merc prop shaft

Hopefully the nut was brass and didn't damage the stainless steel shaft threads being the softer of the two. Try popping the brass out of the threads on the shaft with a sharp pointed object like a ice pick or awl. Then use a wire wheel on a drill to clean them up or you can run a die down them. As for the size not positive but can tell you it's larger than 5/8" and smaller than 1".

 

[fishrdan]

Re: Cross thread 3.0 Merc prop shaft

I don't remember the die size (3/4"x16P???), but I cleaned up the prop shaft on my Mercruiser drive. It's a big honking $20 die that won't fit into a normal die wrench, but it's possible to clean up the threads if you are careful, go sloooowwww and use lots of lubricant. If you haven't done this type of work before, it might be best to leave it to the pro's as you could make a bigger mess of it.

If it's just the first thread or two that's messed up, you could use a small fine pitched "V" file and straighten out the threads. There are also "thread files" that have notches cut in them to match the bolt's pitch, I haven't used one and can't comment on how well they work.

 

[Fun Times]

Re: Cross thread 3.0 Merc prop shaft

3/4-16 thread size on the prop shaft. Just recently my prop shaft cleaned up nicely to.

http://forums.iboats.com/showthread.php?t=515948

Good luck.

 

[fishrdan]

Re: Cross thread 3.0 Merc prop shaft

LOL, Good call on dredging up the thread I posted last fall Fun Times...

 

[1960vw]

Re: Cross thread 3.0 Merc prop shaft

Thanks for the great input! i'm taking in the shop to change out the impeller. Hopefully they won't gouge me to fix it!