# Repair cast aluminum crack on lower gear housing



## TexasLoneStar56 (Nov 6, 2014)

In restoring an old 1955 Merc, I've discovered a crack in the lower gear housing. :x It's cast aluminum. I know it can be tig welded, and that can get rather pricey. I'd also have to remove all the parts on the inside to have it professionally tig welded.

What's the opinion of JB Weld? Will it do the job?

The crack is about 1.5" long, vertical. The crack itself is tiny, maybe 1/16", or less.

Thanks for your replies. I need all the help I can get, and I appreciate it.


----------



## PA Delaware Fisher (Nov 6, 2014)

Not sure how the jb weld will handle what your asking it to but i can say I've never seen a successful jb weld job and if it was even close to being successful it was just temporary.


----------



## Pappy (Nov 6, 2014)

Is the crack where gearcase oil is leaking from it?
I would think that the only way you will get JB weld to hold in this area is to completely disassemble the gearcase, stop drill the crack at both ends, thoroughly clean away all oil, grind out the crack on both sides, do your JB weld job and cross your fingers. 
Also you need to find out what caused the crack in the first place unless it was a freeze crack.


----------



## RiverBottomOutdoors (Nov 7, 2014)

No, JB Weld is not the solution. It won't last.


----------



## TexasLoneStar56 (Nov 7, 2014)

A couple of pics of the crack.


----------



## TexasLoneStar56 (Nov 7, 2014)

After posting yesterday, I re-examined this crack. It is not 1/6" at all. In fact, I can't even get a fingernail in it. I have to only assume it is from a freeze. Yes, it has leaked oil before, but not sure when. :?:


----------



## TexasLoneStar56 (Nov 7, 2014)

I did some research yesterday on some stuff that is suppose to work like brazing. BUT, you have to heat the metal with a propane torch to apply. The rod is never heated. It is suppose to melt into place, like silver does.

So....whether I have it tig welded, or try this other stuff, I'll have to disassemble it so as to heat the cast. :evil:

I know it has to be cleaned before anything can be done to remove oil, dirt.....
Paint thinner perhaps?

And, thanks for the tip on the stop drill holes. Great advice!

I welcome any other comments.

Keith


----------



## Y_J (Nov 7, 2014)

TexasLoneStar56 said:


> I did some research yesterday on some stuff that is suppose to work like brazing. BUT, you have to heat the metal with a propane torch to apply. The rod is never heated. It is suppose to melt into place, like silver does.
> 
> So....whether I have it tig welded, or try this other stuff, I'll have to disassemble it so as to heat the cast. :evil:
> 
> ...


Use a Stainless Steel brush on the area you'll be brazing. The rod you'll be using is actually a low temp aluminum rod. The base metal has to reach 720 degrees for the rod to melt. Once cooled down after the job, it is actually stronger than the base metal. You can then grind, sand and paint and never know the crack was there. Well, you will but no one else will LOL.. 
I've used this technique on my tin can several times during it's makeover.


----------



## KMixson (Nov 8, 2014)

RiverBottomOutdoors said:


> No, JB Weld is not the solution. It won't last.



I agree with you on that. I know JB Weld is used in a lot of situations and you may have luck with it. I would only use it as a temporary fix if I do use it. I have seen it give way too many times.


----------



## lckstckn2smknbrls (Nov 8, 2014)

Do you have a high school or community college with a welding program in your area?


----------



## Moedaddy (Nov 9, 2014)

Jb weld will not last. More than likely it will cost you more in the long run. Just do it right the first time and be done with it.


----------



## TexasLoneStar56 (Nov 9, 2014)

lckstckn2smknbrls said:


> Do you have a high school or community college with a welding program in your area?



Yes we do. I'm not sure I'd trust a high school kid welding on this old cast. I remember stick welding in FFA. Just took me once at having to grind off all that mess to learn how to figure 8. :? 
But, it is a good idea. I'll check with the Ag teacher and see if he can do it. Thanks for the advice!


----------



## TexasLoneStar56 (Nov 9, 2014)

YJ,
Yes indeed a stainless brush. I think the one I read about said something about having to heat the metal to about 500. I could be mistaken though. I need to read it again.
Thanks for the advice. I appreciate it. 8) 

And, thanks for the heads up on the JB weld. You never know till you ask, and now I know not to use JB weld on this particular item.

Thanks for all the comments! Very much appreciated!


----------



## Boat2fast (Nov 22, 2014)

Look for a parts engine. Talk to some of the old guys in town. Ask at the shops. That's how you find old motors. Sometimes it can really pay off.


----------



## TexasLoneStar56 (Nov 22, 2014)

Boat2fast said:


> Look for a parts engine. Talk to some of the old guys in town. Ask at the shops. That's how you find old motors. Sometimes it can really pay off.



Thank you for that advice. I appreciate it.


----------

