Welding crack in lower unit

norman2013

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Hello, I have a 1984 mercury 18xd that i just recently purchased. The lower unit has a 5 inch crack on the bottom. Iv heard that welding it will work and iv also heard that jb weld works as well? Any suggestions?
 

wired247

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Re: Welding crack in lower unit

I'd weld it but you can use JB weld if its not in a stressed area. If it doesnt work with the JB weld you can always get it welded later.
 

erie_guy

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Jan 16, 2007
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Re: Welding crack in lower unit

Depends where the crack is located. If it is into the oil gallery, the JB-Weld will probably not bond well and the leak will return. I would give the JB solution the first try as it would only cost a few dollars. My advice would be to clean the crack as well as possible and roughen up the edges of the crack to get a fresh bonding surface.

Best of luck !!
 

wired247

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Re: Welding crack in lower unit

A good TIG welder or a kid with a good spool gun and a grinder could fix that. JB weld wont do it.
 

Faztbullet

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Re: Welding crack in lower unit

Welding wont fix that as it will draw housing and pinion aligment can be thrown out. Skags/cavation plates along with holes where gear/bearing has popped a hole are ok to weld. Usually welding on sides for large cracks result in case warpage which I seen bearing carriers become unremoveable,foward bear races **** and result in gear failure. BRP has a alignment checker to check housing to see if warped and I have thrown housings away that looked like new due to being warped.
 

norman2013

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Re: Welding crack in lower unit

If there is a chance that it may work, I was planning on taking it to a professional welder so that he could do the job right?
 

wired247

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Re: Welding crack in lower unit

If it doesnt work you need to buy a new lower. If it does work you don't have to buy a new lower. See how that works?
 

norman2013

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Re: Welding crack in lower unit

Update on the lower unit weld! Took it in yesterday to a professional welding company and they had a guy there that specialized in welding boats. He said it would be no problem. So a few hours later and only $20 he had it done. Image 6.jpg
 

wired247

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Re: Welding crack in lower unit

Looks like he used a DC spool gun. You can lay down a LOT of metal with one and not do much metal distortion. I'll bet that right after he laid that down you could have put your hand right on the weld and not even gotten close to being burned. If it craps out you are only out $20 more on your way to buying a new lower.
 

mercurymang

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Jul 14, 2012
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850
Re: Welding crack in lower unit

Lol. Looks like frankenstein. Are you going to grind down the weld?
 

norman2013

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Dec 8, 2013
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Re: Welding crack in lower unit

I wasnt planning on it. Id rather the weld be strong then be week. I panted the area black
 

bruceb58

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Re: Welding crack in lower unit

If it got real hot, your seals may be toast.
 

wired247

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Re: Welding crack in lower unit

If it got real hot, your seals may be toast.

If he welded it with a spool gun as it appears it wouldnt have gotten real hot. TIG welding crappy merc cast stuff WILL transfer a LOT of heat as you have to heat the whole piece up before you get good weld penetration. With ER5356 wire and a push pull gun or a spool gun on a DC source you can lay your hand on the work immediately after welding and it will just be warm to the touch.
 

bruceb58

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Re: Welding crack in lower unit

If he welded it with a spool gun as it appears it wouldnt have gotten real hot. TIG welding crappy merc cast stuff WILL transfer a LOT of heat as you have to heat the whole piece up before you get good weld penetration. With ER5356 wire and a push pull gun or a spool gun on a DC source you can lay your hand on the work immediately after welding and it will just be warm to the touch.
No matter how he welded it(TIG or MIG), the base metal has to melt in order to get good penetration. For aluminum, that takes a lot of heat since aluminum sucks the heat away. If you can hold a hand on a weld right after you are done, your wire feed is either too high or your voltage is too low. I have welded with both and prefer TIG.
 
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