Welding cracked cast iron manifold

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A friend dropped off the exhaust manifold from a Massey Ferguson 1130 tractor (8 cylinder diesel-she's a beast !).  There is a hairline crack that goes 2/3rds of the way around the tube.I've read everything I could find on the subject, but this is my first attempt at welding cast iron.  I am prepared for pre and post heating, grind out the crack a little bit, etc.  My question is about rod selection.  I picked up a package of Nomacast as it said it was good for heat-affected, contaminated, cast iron.  Then I read on here that most use 55 to 95 nickel rods.  The Nomacast says it is nickel-free.  Is it still a good choice for this repair ?  Why is it nickel free?  I don't need to machine it or anything.Anyone have a good experience with the nickel-free Nomacast ?  Appreciate any advice.
Reply:i've never welded CI w/ Nomacast , but i am familliar w/ lincoln Ferroweld - which is the same idea .  i like it great for ornamental, non-structural , non-cosmetic , (cheap) cast iron welds .for the job  you want to do, i'd use NI-99 or 55. it's not going to be hard and brittle like nomacast  . it costsabout $40/lb for nickel rod vs $5/lb  for ferroweld type . i have some Harris NI-59that i'm partial to. nickel welds look like... shiny nickel , so if that's an issue - use the cheap stuff andhope for the best .Miller S60 feederCobramatic push/pull feederMiller CP-252tsLincoln Tig250/Tig250Lincoln weldpak 100 -italianC-H 90A- italianHarris & Victor O\Afull manual & CNC machine shop
Reply:I've used the NOMA-CAST rod with good success. In the application you are doing, I believe it will work better than NI-Rod. That manifold casting will be a bugger to weld just so you know.
Reply:The last cast repair I did was a housing on my Gravely tractors gear box .http://weldingweb.com/vbb/showthread.php...i+gravely+castThats how I did it, TIG with 309 fillerDisclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:Thanks guys !  I think I'll try the Nomacast and see how it goes.  I have a Miller Maxstar 150 , but I'm still learning TIG.  I don't feel comfy trying to TIG someone else's piece.  If it was mine....I'd give it a whirl !
Reply:Some say O/A is the best method for welding cast iron when the entire piece can be pre & post heated real good. It does allow you to do a repair using cast iron filler, and that should prevent future problems like cracking due to diffrent thermal expansion of the base metal and the filler.
Reply:Long story short.....it held without cracking.  I couldn't keep it from undercutting, but other than that it worked OK.  I practiced on a different piece of scrap cast.  It welded great.....the manifold did not.  I hope I never have to do a critical weld on cast.Thanks for all the tips!Verdict - Nomacast is ok stuff.  The operator (me) is less than great.
Reply:Been there, done that. O/A welding with cast iron filler and flux is by far the best from a technical perspective. But.....its a lot of work in preperation, process and technique. This is why the "lazy mans" nickel based arc brazing/welding rods came on the market as a way to do a barely acceptable job with less work than the O/A process which had been done since about 1905 ( meaning the silicon doped iron filler and flux process which we still use today ).
Reply:I was told when I had a cracked turbo manifold on my car to preheat it and use a mig with standard er70s-6 wire. Is this wrong? Or does nickel just work better?Torchmate 2x2 CNC with Flashcut CNC controlsHypertherm Powermax45 Esab ET220i Razorweld 195 MigRazorweld 200ac/dc TigTormach 770, Tormach xstechRazorweld, Vipercut/Vipermig, SSC Foot Pedal Dealer
Reply:It is very, very, very wrong to weld cast iron that way... but you probably had a cast steel manifold, and that's an other kettle of fish. Still doesn't make it right though.And by the way, just because something is wrong that doesn't mean it's never going to work, it's just less likely to do so.
Reply:is it acceptable practice to braze a cracked manifold?  or is that just a bandaid?
Reply:Originally Posted by G-sonIt is very, very, very wrong to weld cast iron that way... but you probably had a cast steel manifold, and that's an other kettle of fish. Still doesn't make it right though.And by the way, just because something is wrong that doesn't mean it's never going to work, it's just less likely to do so.
Reply:One way I've read but not tried is to use a sharp chisel and hammer on a corner edge. Cast steel is soft enough so you can chisel off a thin "wire" along the edge, while cast iron is brittle and only will chip off piece by piece.Another method should be to check grinding spark colour, diffrent metals give diffrent sparks.Brazing is generally a good repair method for cast iron, but unsuitable for anything being used at too high temperature. Might be fine on the manifold of a low performance engine, but wouldn't work on a turbo manifold that gets red hot after a few minutes of full throttle.
Reply:I've brazed Toyota Cast Iron Exhaust Manifolds with good success
Reply:Originally Posted by G-sonSome say O/A is the best method for welding cast iron when the entire piece can be pre & post heated real good. It does allow you to do a repair using cast iron filler, and that should prevent future problems like cracking due to diffrent thermal expansion of the base metal and the filler.
Reply:Has anyone used one of these amweld torches? The website is awfull & the vidoes short and poorly/ unprofessionally made. There aren't even prices listed for the kits. That said if the torches work like they say, it may be a nice thing to have. Oh the hoses have odd fittings too and the mention that but don't fully explain it. It leaves more questions than it answers. I would like to know more but if the web site is any indication it seems,  well unprofessional. Like I said anyone use on of these?Miller thunderbolt 250Decastar 135ERecovering tool-o-holic ESAB OAI have been interested or involved in Electrical, Fire Alarm, Auto, Marine, Welding, Electronics ETC to name a just a few. So YES you can own too many tools.
Reply:I've got an old Dillon, the same as the Henrob/Cobra 2000/DHC2000 but the name has changed through the years. Bought mine used a couple of years ago, manufacturing date says 1985 and it's still going strong.I know nothing about Amweld, I just like their demo videos on Youtube - there are other sellers like www.cutlikeplasma.com and a guy from there ("Henrob Jim" I think) has been answering alot of questions about it at the Metalmeet forum. Cutlikeplasma also has some videos, but older and lower quality.Personally, I love it. But I am just an amateur, and this is the only welder I have and can use so I have nothing else to compare it to. I did my research, thought about what kind of welding I would be doing, where I'd be doing it (limited access to electricity) and the Dillon is what ended up fitting my needs and "wants" best - the only option here would have been a TIG and at the same price that would mean one from the stoneage or some chinese junk - the difficulty getting parts if it breaks made me run away from those options! Doing that research I heard and read alot about what other people think about it. Some love it, others hate it, often for not being able to adapt to the pistolgrip after learning to use conventional O/A welders first. It does do what they say it does, but alot of other quality O/A welders will probably do the same jobs equally well.
Reply:Originally Posted by bl8tantLong story short.....it held without cracking.  I couldn't keep it from undercutting, but other than that it worked OK.  I practiced on a different piece of scrap cast.  It welded great.....the manifold did not.  I hope I never have to do a critical weld on cast.Thanks for all the tips!Verdict - Nomacast is ok stuff.  The operator (me) is less than great.
Reply:Method I've used for years with great success: grind the crack, drill stop at ends of crack for stress relief. Without drill stops it will just start a new crack right past where you welded. I use a DC arc welder and high nickel rod, but it's been a while, can't remember the rod's nomenclature, but they're red coated. It's a standard DC Arc rod for cast iron, LWS should know what it is.Prior to starting welding, build up a monster barbecue fire with lots and lots of charcoal in something big enough to take the whole part, and have a lid to cover it too. Preheat the piece before starting weld and even during welding if you have a helper. Soon as it's done welding toss it directly onto barbecue's hot fire and thick bed of coals, close the lid and let it bake with a slight vent allowed for airflow. Leave it to bake overnight undisturbed.When you come back in the morning the cast iron has been normalized throughout its entire structure at the same heat, has cooled gradually at the same descending temp throughout, all the way to cold. It will be ready for anything you can throw at it.  It's easy, cheap, low tech and works just fine including cast iron cylinder heads and exhaust manifolds. However on some cylinder heads and even exhaust manifolds I prefer brazing instead of arc.
Reply:the hardest part imo is determining your material. I did some vises that where grey cast by using preheat and buttering them with nickel then filling with 7018 and then post heating and ending it in a pile of sand over night. If you let it cool naturally the HAZ will become martensitic and just crack all over again because of the carbon content.hope this helps some. Im sure there is an easier way but this is what worked for me.speedway series 125 flux core welder