Welded a Cat 650 Dozer stack (MIG)

   / Welded a Cat 650 Dozer stack (MIG) #1  

Sodo

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Lots of members (I think) are trying to decide whether to get a MIG or a stick-welder. Or would like to see examples of tasks that can be accomplished with the MIG they have. Here's an example (,,,,,,way on the thin end ! ) of a repair that can be done with a MIG.

Today a freind asked if I could fix the exhaust stack on a dozer. I said yes. How difficult could it be? Well I had NO idea the metal on this beast would be so thin. It must be 22ga (1/32 inch). And rusty too, so even thinner than 22ga in many areas. It was not an easy weld. Wherever it was rusty was constantly filling holes, and where I had full thickness (22ga) it wasn't really easy.

Heres some pics.

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The rusted out part is a cone reducer (from 5" to 4"). This stuff was underneath a wrap of coffee cans and pipe clamps. When I said I'd fix it I didn't know what was under there.

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Decided to proceed. At this point, seeing how rusty and run-out this stack is, I'm not concerned how it looks. Just want to get the stack on, and exhaust away from the operator (at least for awhile). Also hoping he'll let me use the dozer! If the friend wants to bring the correct materials such as an actual reducer, I'll weld that in for him.

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Luckily this exh stack is more like a "guide" attached to the "hood". It just sets over the manifold and guides the exhaust up and away. Its not a sealed exhaust pipe. I'm hoping the exhaust velocity actually sucks air into those holes rather than letting exhaust out. I didn't start the engine, just barely had time to weld and RUN!

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   / Welded a Cat 650 Dozer stack (MIG) #3  
Well, your plan was good, but you didnt finish the job. You should have welded up the slits because thats where the exhaust is going to blow out I think. Also, if the dozer sets outside in the weather, thats where rain water is going to run into the engine.
 
   / Welded a Cat 650 Dozer stack (MIG) #4  
I gotta ask why?

That pipe and that condition, Id just run to the local muffler shop and get a piece of pipe for $20 and get them to flare it. By the time you figure in gas and wire and other consumables, you spent that much at least, plus as pointed out, the job isnt finished, water will get in through the cuts and exhaust will blow out from them.

Now if this was done "for fun"... just weld up the cuts and call it good.
 
   / Welded a Cat 650 Dozer stack (MIG)
  • Thread Starter
#5  
If this welding job makes the operator happy doing work for me, I'm happy. I have him for a couple days. If he wants to bring me the proper materials to repair it I'll put it in. He has FOUR of these 650Gs, with 6-way (?) blade, doesn't use them, won't sell any. Not that I need to own one just seems a shame they are sitting.

Luckily this exh stack is more like a "guide" attached to the "hood". It just sets over the manifold and guides the exhaust up and away. Its not a sealed exhaust pipe. I'm hoping the exhaust velocity actually sucks air into those holes rather than letting exhaust out. I didn't start the engine, just barely had time to weld and RUN!

Exh manifold (on the engine below) has appx 3" diameter vertical stack. When you set the "hood" down, this 5" diameter cone drops over the 3" stack, there is an inch of space all around. I suspect to allow for flex that would otherwise break the exhaust manifold. Above the hood it reduces to 4" stack. Can't weld up the slits, I'd be there all day. I suspect that its been wrapped with coffeecans for 10 years, which probably didn't seal all that great.
 
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   / Welded a Cat 650 Dozer stack (MIG) #6  
Just for future reference, they do make a carbon backer that you can lay behind that thin metal. Weld wont stick to it and it would allow you to weld those slits up in one pass. At work we use those backers to weld up, (mig and stick), switch and frog points where you have to build up the wear and still retain the original shapes. It makes for easier grinding. Should work equally as well for thin sheet metal.
 
   / Welded a Cat 650 Dozer stack (MIG) #7  
I gotta ask why?

That pipe and that condition, Id just run to the local muffler shop and get a piece of pipe for $20 and get them to flare it. By the time you figure in gas and wire and other consumables, you spent that much at least, plus as pointed out, the job isnt finished, water will get in through the cuts and exhaust will blow out from them.

Now if this was done "for fun"... just weld up the cuts and call it good.

Ditto. That is going to be miserable to run with the exhaust coming out of the holes.
 
   / Welded a Cat 650 Dozer stack (MIG)
  • Thread Starter
#8  
Carbon backer that's interesting. I see copper welding backers on eBay but none are carbon.

I guess we'll see if exhaust comes out or air sucks in. Maybe we should take bets. :D

cat_exh_16.jpg

I've drawn the inner pipe as it should be, but in reality it's about half gone, doesn't extend up to the cone anymore. Further repair is outside my job description for the moment. But if he wants to reduce my dozer rental charge its something I can do that he can't,,,,,,
 
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   / Welded a Cat 650 Dozer stack (MIG) #9  
I just got thru talking to the welder at work about those carbon backers. They are in fact pure carbon. I was trying to find the proper name so I could look them up but he said he always just called them carbon backers. He orders them out of the company material catalog with a part number that doesnt mean anything outside the company. I'll have to do a little more investigation to see if I can find the commercial name for the product.
 
   / Welded a Cat 650 Dozer stack (MIG)
  • Thread Starter
#10  
That sounds like a useful item. Does copper work too? I have copper.
 
 
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