Some thoughts on the best or preferred method of a cast iron engine block repair....

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Hi all,I did a job today for a body shop that discovered a pair of broken out engine mount holes cast into the block.  One was sheared off and the other was actually broken out.  My general policy regarding cast iron engine block repairs is 1) take on those repairs that are on the extremities of the block where the part (or area) in question is free to expand and contract without restriction to prevent cracking.  2) Use bronze to braze the part back or to build up the area.  Part of my reasoning is that I am concerned with creating stress cracks from the concentrated heat of arc welding a repair like this.  So I had a few questions of others who routinely do these types of repairs.The only concern I had when I started this repair was that the transmission bell housing was bolted tightly to the engine block at two points where the damage was so I removed the bolts holding the bell near where I was going to be welding so that the area could expand and contract.  I felt the bolted are might lead to a crack situation.   The repair went smoothly and I drilled and tapped fresh holes.If I had chose to use some ni-rod here are my questions:1) could I have welded it out in one shot as I did with the brazing?  Would the same logic apply to the arc welded approach, that is the area is free to expand and contract freely?  My fear is that the intense heat of the arc could lead to cracking if I did so as the metal would be super heated instantly as opposed to the torch which would heat it relatively slowly.2) Is the "cold" method the right way to have arc welded this repair?  That is, run small beads and let each one cool before beginning the next one until it is all built up?3) Could I have used silicone bronze and tig welded it?  Slowly, right?4)  How would others have done this type of repair?I probably get about three or four of these types of repair a year and they have all been brazed.  I avoid those that are inboard on the block unless, as mentioned they are at an extremity like an air conditioner mounting hole, etc. where the part can expand (and contract) freely.The reason I stick with the brazing approach is because it has worked for me, not necessarily because I think it is better.  I'm somewhat timid to try the other route as my only experience using the nickel rods has been with small bench type repairs on cast iron parts (exhaust manifold, cast iron drill press base, etc.).Thanks in advance for your feedback,Tony
Reply:The heavy equip guys used to use nickel-copper mig wire but a roll probably costs as much as a car in todays phony money movie.Brazing is underrated.I would have brazed it too. Unless a chump with Popeye arms gets nutty with the ratchet(or worse yet-impact) that repair will hold until that car goes to China for recycling into Harboring Fright tools.Bubble gumTooth pixDuct tapeBlack glueGBMF hammerScrew gun --bad battery (see above)
Reply:I've never liked brazing so I don't do it much. I would have done pretty much what you did but with ni99. I've done a few similar on tractor housings and such with good results.
Reply:Thanks for the feedback guys.  What I was anxious to know is what procedure would be used to repair this using one of the arc processes?  could this have been welded out continuously, rod after rod?  Or small bead after small bead, letting it cool each time so that the area gets no hotter than the bare hand can take?  What do you all think?Thanks,Tony
Reply:Generally I heat iron to about650-800, weld with Hilco Nickel Iron and let it cool as slow as possible. Even with brazing. Hard to pull off with a block unless it were out and stripped. I suppose some heavy rosebud time and a bundle of blankets might be a go ?.Check out Muggyweld dawt kom. Some of the guys like hi$ produkt$Bubble gumTooth pixDuct tapeBlack glueGBMF hammerScrew gun --bad battery (see above)
Reply:I have always preferred brazing myself.Idealarc 250AC 225SVictor OA-older made in USA stuff.And a crap ton of other stuff.
Reply:Get it hot and keep it hot til done. 5-600 deg or so to start and don't over do it so it gets too hot, but don't let it fall below about 500 either.
Reply:The Tinman has an instructional video for rent where he shows you step by step how to repair weld cast iron.  He covers it with a insulative blanket, Preheats the metal, then welds quickly and throws it in a hot stove to slowly cool as the fire does down over night!  Seems like controlling the cooling rate is the key to prevent cracking.
Reply:Originally Posted by BurpeeThe heavy equip guys used to use nickel-copper mig wire but a roll probably costs as much as a car in todays phony money movie.
Reply:Brazing is indeed often very unappreciated.  In my opinion, you made the safest and can not hardly miss repair.  When dealing with the worst of castings then brazing is usually the wisest choice.  I agree your repair looks likely to last the remaining life of the unit (and craftmenship quite good by the way).  The only thing that I could think of that might it a tad stonger is to braze studs or boltheads in to the repair and then use nuts at the mount.  Not sure if design would have permitted this or not though and this way your threads would be tightening on steel stud to steel nut instead of steel bolt to brass/bronze threads in repair.  My next choice would have been migging/wire feeder.  Special alloy would likely be better than standard wire although I have had luck repairing some castings with plain ole E71T-11 flux core.  That said there is some risks with migging castes so definitely much more risky than your brazing repair.Stick welding it.  I absolutely would not do that.  My stick welding attempts have always went way bad even when I used expensive rods. FWIW:   CEP has posted some interesting reading in the past on proper cast repairs and I believe what I have read in those postings based on my limited experience.  Long story short of those specialists is that arc welding (even migging to an extent) is the absolute worst way to repair castings as it creates a very large and very brittle Heat Affected Zone.  Castings should ideally be reapired with an Acetylene torch using similar cast filler (sometimes even old piston rings can be salvaged for filler), but even then special procedures must be followed for the repair to be successful.  Brazing is next best repair and very forgiving if proper procedures are not followed and usually the best for amateurs like me who do not follow the book.Last edited by rankrank1; 01-18-2014 at 01:25 PM.
Reply:Originally Posted by rankrank1Stick welding it.  I absolutely would not do that.  My stick welding attempts have always went way bad even when I used expensive rods.
Reply:I love those type jobs. Especially if someone says it can't be done. LOL. Is that a casting from an old case tractor?
Reply:Hi fellas (and any lurking ladies out there),those are great suggestions and great shots of a repair on that tractor part.  I love the idea of brazing bolts into the repair on that block job.  The thought NEVER even entered my mind yet it makes so much sense.  Of course!!!  That would remove any fear of stripping the threads.  Yes, the design would have allowed for that because what bolted against those broken out holes was in essence an "L" bracket shaped motor mount.  There was nothing that would have interfered with using a nut and washer to bolt the thing in place instead of a bolt into the holes.  I will remember that from now on and when presented with this type of repair I will use that approach unless as you stated the design would not permit, (like something interfering with the part sliding into place if a stud were sticking out which is what would happen if I brazed a bolt sticking out).I think the reason that the tractor repair went well with the arc welding approach is that the part being welded was not positioned so that it would hit some kind of restraint.  Instead it was free to expand outward and contract back into its original size.    I have never done such an extensive cast repair cold like that as I would have preheated it first.  But in part that was what I was looking for in terms of procedure.  Could a repair where the part was free to "float", expand and contract back be done in one shot like I did when I brazed those holes back into place as shown in the pictures of my repair job.It would seem that if you stick welded (or wire welded it) without much heat pre and post, then it would seem to hold that the same principle is in play which is that if the part can expand and contract freely, then no special requirements as far as heating and maintaining heat is a major concern. If this were an engine block  and we were repairing a crack over a water jacket for example, I am inclined to think that such a job would require having the motor stripped apart and pre heated and maintained while it was being welded (or brazed) as there would be too many areas where the welded area would "bump against" a gusset or flange area that would NOT allow it to expand or would NOT allow it to contract back because it was not all at the same temperature.  It would expand and contract at different rates, leading to the cracking.  That is why I turn down jobs that call for welding on the interior areas of an engine, (water jackets, crank case areas, etc.) because I feel I will be walking into a trap with no way out gracefully.When I worked in the steel mills in Chicago during the 70's, we routinely brazed huge cast iron parts such as an air compressor or gear box cases, machine bases, etc. The only way we did this was to have in some cases several gas burners on the part for hours at a time prior to and during the actual brazing process so that the entire part was at the same temperature and then we covered it with piles of asbestos blankets to keep the heat in and we turned the burners down real low and left them overnight and finally turned off the burners and let it cool nice and slow.  The result was a part that was good as new.  Sometimes we would add steel gussets or plates to reinforce a part before putting back into service.   I learned to have a great respect for the capabilities of brazed repair.So I think it is safe to say that I could have done that repair using arc with minimum pre-heat and welded it out knowing that it was free to expand and contract.  What do you guys (and / or ladies) think?Thanks,Tony
Reply:Originally Posted by aametalmasterI really like Crown Alloys 44-30 Cast Iron Mig Wire and the price isn't any more than than quality Ni rod and there isn't any waste from rod stubs...Bob
Reply:Originally Posted by welderjI love those type jobs. Especially if someone says it can't be done. LOL. Is that a casting from an old case tractor?
Reply:Originally Posted by Drf255Love the adapter you made.
Reply:And a few more of a broken bell housing for a hydraulic pump...Bob Attached ImagesBob WrightSalem, Ohio  Birthplace of the Silver & Deming Drillhttp://groups.yahoo.com/group/southbend10k/http://groups.yahoo.com/group/sawking/1999 Miller MM185 w/ Miller 185 Spoolmate spoolgun
Reply:And a few more. I really didn't want to hog the OP thread just showing different ways to do the same job...Bob Attached ImagesBob WrightSalem, Ohio  Birthplace of the Silver & Deming Drillhttp://groups.yahoo.com/group/southbend10k/http://groups.yahoo.com/group/sawking/1999 Miller MM185 w/ Miller 185 Spoolmate spoolgun
Reply:Hi Bob,those are great shots and nice repairs.  This may sound simple, but I assume you did no pre-heat beyond maybe taking the chill out of the metal?  All except the first one with multiple breaks are the type of repair I meant where the part is towards the extremity of the casting.  Thus the heated area could expand and contract freely.  No?  Thanks for the pictures.TonyLast edited by therrera; 01-19-2014 at 10:03 AM.Reason: for clarity
Reply:What sort of amperage are you running with that .035 ? Looking good !Bubble gumTooth pixDuct tapeBlack glueGBMF hammerScrew gun --bad battery (see above)
Reply:Looks like I need to keep some old copper around. Much better than using a burr afterwards.
Reply:As Burpee suggested, check out Muggyweld.com.   Here is just one brief description and video they have about welding cast iron.  Seems that Muggyweld makes a few different types of electrodes that are easier to use than Ni-rod. http://muggyweld.com/welding-cast-ironA Liberal is someone who lives in a gated community with private security,  but says that a boarder fence won't work and people don't need guns for self protection.