welding on the chain box

[rsherril]

My chain box has nine inch crack along the top inside weld that weeps a little oil from the box. Is it feasible to go over this with a new arc weld? Would I need to drain the lubricating fluid, (JD hydraulic fluid)? My JB epoxy weld fix cracked after a short time. I'm trying some plumbers glue now and will stop there if it holds-up. Concerned about water entering the box if the plumbing stuff leaks too.

 

[lumberjack]

You will likely need to drill the ends of the crack to stop it spreading and grind out the crack for a better weld. Draining the fluid will be required if the contamination from drilling is unacceptable.

I welded up a 100 gallon fuel tank last week with a similar length crack along a bottom weld. I emptied the tank, but then again it's hard to lift the tank when it's full, and it's hard to weld through diesel leaking out.

 

[rsherril]

Thanks for the advice to drill the ends of the crack. I would not have thought of that. My main concern was what the heat from the arc would do. I understand that hdy. fluid is not as explosive as diesel fuel fumes. Many years ago I was warned about welding on barrels that contained such fumes. I understand that filling the container with inert gas such as Carbon Dioxide or even exhaust from auto engine will minimize such risks. Would rather add a little fluid once in awhile rather than risk blowing up my chain box or worse.

 

[Nige]

Can you post a photo of the crack..? It helps to see what you're up against.

 

[rsherril]

Where the top plate is welded to the inside of the box. The gray is JB weld, which I have removed and replaced with a flexible plumber goo. Will take it out today to clean up some flood damage and see if it holds tight. I haven't noticed it increasing in length, but have it marked now for future reference.

 

[Nige]

To me that looks like the factory went real skinny on the original weld when they built it. You have the perfect opportunity to do something good because the 2 plates where the crack is will create a natural 90-degree fillet, so all you have to do is "fill it" (pardon the pun) with weld.

Grind as much of the old weld out then make a groove in it using a 4" grinder and as narrow a cutoff wheel as you can get hold of. Grind down carefully and try to take as muchj of the factory weld out as possible without breaking through to the inside. Go at least 1" past both ends of the crack that's visible on the surface - see if you can see any trace of the crack in that last inch. If you can, grind some more length until you've taken out the old weld and have at least 1" at each end where no crack is visible even if you grind the weld down right to the root. Warm everything up to about 150 degreesF to drive out any moisture and have at 'er with whatever diameter of E7018 electrode you're comfortable with. I wouldn't worry about draining the oil, not necessary.

 

[rsherril]

The plumber goo seemed stopped the leak for now but after reading Nige's comment about grinding and rewelding with the E7018 electrode I took another look and realized the structural nature of the chain box. It does a lot more than provide a oil bath for the chains. As I have a unopened package of low hydrogen 7018 and said grinding tools I will go ahead with the project. Didn't understand that 7018 provided deeper penetration and a stronger weld than my 6013 until I looked it up. So much to learn.

 

[Nige]

Don't be frightened to put plenty of heat in it when you weld it. The more liquid the weld metal the more it will melt the structural plates of the tandem housing and therefore the better weld penetration you'll get.