Repair on a cast iron engine block

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Hello all,I hope you all don't mind I pick your collective brains.  A client called me tonight and sent me pictures of a broken alternator mounting lug on a cast iron engine block.  I usually shy away from cast iron engine block repairs as my success rate is only 50-50 when doing a repair on the interior of an engine such as around a water jacket, etc.I readily take on repairs that involve the outer perimeter of an engine where the part can expand and contract without interacting with other parts of the casting that could cause a new fracture during the contraction process.  I have had 100% success with this strategy and have used brass rod to braze such parts or build up material.I am not sure about this repair only because the broken lug base is close to other parts of the engine casting such as next to a freeze plug.  The location of the break has me lean towards using ni-rod for the repair as I can lay little beads, peen them and never let it get hotter than I can put my bare hand against it.  This approach has the added benefit in my opinion as a broken bolt inside the broken base can serve as a tie in point for the nickel rod to cast iron.Any opinions from my welding brothers (or sisters) out there if fix-it land?Ni-rod it or braze it with brass?  I attach a picture of a similar type of repair done with brass.  However it was in a simple part of the engine casting and not near other dips and stiffeners as in this case.All opinions welcomed,Tony Attached Images
Reply:I would definitely use TIG, the heat from oa would scare me in that area. Brazing is probably the safest especially since the alternator vibrates a lot and would encourage cracking in a weld.
Reply:Hi chirsbmx68,Thanks for your input.  I was thinking of using stick welding using a nickel based rod.  Wouldn't TIG generate greater heat than stick?  Your comment that brazing would be better from a vibration standpoint indicates that it would be a preferred filler metal?In a website devoted to welding (www.weldingtipsandtricks.com), the author suggests for cast iron using an aluminum bronze alloy TIG rod.  Think this would comply with your thinking  of using a brass or bronze alloy as in brazing? See the link below:http://www.weldingtipsandtricks.com/...cast-iron.htmlWhat do you think?Thanks,Tony
Reply:How long is the piece that broke off . . . why did it break?I'd consider a mechanical repair.  Increase the thread to the next size . . . even if it meant drilling through into the water jacket.  Flatten the broken surface with a 2" angle grinder, install a stud with Loctite (to seal the coolant).  Then make a spacer to replace the piece broken off and drill out the bracket for the larger stud.Dynasty 300DXSmith He/Ar gas mixerMM350PHobart Handler 120Smith LW7, MW5, AW1A
Reply:tig weld and use a ni44 rod
Reply:Hello all,I received the car today in my shop to start the repair on this broken alternator mount.  The owner told me that a mechanic told him that this engine is notorious for breaking at this point.  They usually toss the block and get another one.  I tried finding tig rod for cast iron but it is all special order stuff leading to my next question:I have some Stoody castweld 99 3/32" nickel based stick welding rod.  Can I chip the coating off and use the bare rod with my TIG torch?  Or is the coating  part of the deposited alloy that is needed for this rod to work.This rod is rated by the spec sheet for flat welding only.  I can see the stuff drooping all over the place on me as I try going uphill or overhead with it.  Instead I like the idea of welding with TIG as I have absolute control over the puddle.  I could lay down small beads, peen and let cool then continue until its done.  What do you say?  Anyone?Tony
Reply:I accidentally let a mopar 440 engine that I was building fall over and it broke off the cast iron ear for the alternator mount.  I held the piece in place with one hand while I welded the ear back on with a nickel rod using 90 amps DC + with the stick welder.   It's held for 10 years so far. Just make small spot welds and don't build up the heat too much using the nickel rod.Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:Im guessing your going to pull the engine for the repair?...use what your familiar with, if you have had success with brass no need to change, after repairing as a ( just in case) I would replace the freeze out plug just a cheap insurabce and covering all basis. do you have to piece that broke off?..
Reply:I prefer nickle based rods for these repairs. Hopefully you are going to do the job on your work bench, and not in the vehicle. If you don't have access to tig rods, I wouldn't recommend stripping the flux. You should get the stud out of there, rather than using it as an anchor, and drill the hole oversize. The transition zone between the casting and your weld will be as hard flint. Plug the hole with weld and drill and retap as deep as possible. If you peen the weld properly, you should be able to rebuild the lug. If you have the missing piece, it is probably too short to prep and weld properly.
Reply:Hi Roadkillbobb,No, the engine repair is being done in position.  I had pretty much decided on using the nickel rod with small beads as the only way to prevent the area from heating up and potentially causing cracks or damaging the freeze plug.If I braze, the area will have to get red hot and unlike the repair example (picture shown above) where I used brazing rod, this part of the casting is more complex than that one where the piece I was brazing to was free to expand and contract without running into a stiffener, gusset or other such thing that could create a crack.Part of the money saving aspect of these service calls is being able to do them in position.  If my repair is successful, for a modest sum (anywhere from $80 to $160), the client will save having to pull the engine, locate a decent replacement and reinstall it.Then he (or she) has to worry whether or not the used engine is in fact good which he (or she) won't know until they fire it up.  If it's bad, then it must be pulled and reinstalled again.There are some jobs where I can't perform the repair as there is too much stuff in the way (manifold, etc.) or is in part of the engine where I don't want to take a chance such as around a water jacket or other location where the casting is more complex.I have already run into the problem of new cracks forming.Don't you think it would be better to "cold" weld this repair rather than brazing temperatures?Thanks for your opinions,Tony
Reply:Hello Profab,I saw your post as I was going to put up another reply to other posts.  I am reluctant to try and drill out the  stud.  The owner of the vehicle attempled to sink a new stud into the block using the thread that was left after the break.  However he discovered that the hole only went another 1/4" or so and his plan did not work.  He cut it flush.Part of my concern is that being a mounting point for a bracket, the tolerances are pretty tight, may 1/16"  to an 3/32"or so.  When the bracket is put into position it will have to be close or the bolt won't match up with the new hole.  Granted there is room for oval-ling out the hole in the bracket.What I was going to do was install the bracket into the remaining bolt holes including the piece that broke off (about an inch or so long) and use the bracket to line it up for me. and then tack it in place prior to welding it out. This way I know its where it needs to be.As I write this I realize that the same bracket can be used to serve as a drill guide for a new hole.  Never having done this type of repair in that fashion I am a little hesitant to try an unknown approach.  There are two replies that advocate a mechanical repair.How have people made out in this type of situation?  Do others see my fear of brazing?  On another thread someone posted that the brass is stronger than the base cast iron.I am going to call around some other welding supply houses to see if anyone has some nickel TIG welding rods for use on this project.  If not, stick rod it is.Thanks all,Tony
Reply:If you want to do a mechanical repair, you should still take out the stud. If it is a new stud and is only in 1/4" deep, it should come out easy. You will get a stronger repair if you thread it in, rather than surface mounting it. Stay with stick welding as you are used to the process and how your rod flows.Threaded rod, although not as strong as a stud, would be better in this application (not zinc plated), as its mechanical properties won't be affected as much by welding. (s/s would be an option)IPut in a spacer so that you have sometning to tighten down to.
Reply:Originally Posted by therreraHi Roadkillbobb,No, the engine repair is being done in position.  I had pretty much decided on using the nickel rod with small beads as the only way to prevent the area from heating up and potentially causing cracks or damaging the freeze plug.If I braze, the area will have to get red hot and unlike the repair example (picture shown above) where I used brazing rod, this part of the casting is more complex than that one where the piece I was brazing to was free to expand and contract without running into a stiffener, gusset or other such thing that could create a crack.Part of the money saving aspect of these service calls is being able to do them in position.  If my repair is successful, for a modest sum (anywhere from $80 to $160), the client will save having to pull the engine, locate a decent replacement and reinstall it.Then he (or she) has to worry whether or not the used engine is in fact good which he (or she) won't know until they fire it up.  If it's bad, then it must be pulled and reinstalled again.There are some jobs where I can't perform the repair as there is too much stuff in the way (manifold, etc.) or is in part of the engine where I don't want to take a chance such as around a water jacket or other location where the casting is more complex.I have already run into the problem of new cracks forming.Don't you think it would be better to "cold" weld this repair rather than brazing temperatures?Thanks for your opinions,Tony
Reply:Hello again,The alternator bracket that attaches to this broken mounting point is bolted down and uses a long bolt instead of a stud screwed in the casting.  The physical geometry of the block and how the alternator is mounted does not allow for a stud as it would interfere with the bracket installation.  It must be positioned first and then bolted in place (see pic).I took a picture of the part that's broken more or less in place.  I will bevel it, position it, tack it and weld it out slowly.Thanks,Tony Attached Images
Reply:ProFab is right in suggesting that you remove the stub of the broken bolt before you weld the broken piece back on.  Even if you only gain 1/4" of thread, it will definitely make the repair less likely to fail.  Just be sure to provide a replacement bolt that makes full use of the depth of the threads.Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:Hi all,I couldn't get the bolt stub out so I ended up leaving it in place.  I beveled the  parts, tacked them in position with the alternator bracket in place so that the broken stub would be perfectly in line when welding.I couldn't get the bottom side of the joint so I beefed up the parts I could get at.  I cleaned it up with a die grinder to remove the cold starts and any undercut to prevent the formation of possible cracks.Thanks for your help and advice,Tony Attached ImagesLast edited by therrera; 03-15-2011 at 03:34 AM.Reason: wanted to include photos
Reply:It looks like the bracket uses three mounting points, so that repair should hold up just fine.Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:Hi DougAustinTX,Thanks for your input.  I was curious.  In general, are ni-rod repairs as strong or stronger than the base metal?Tony
Reply:Originally Posted by therreraHi DougAustinTX,Thanks for your input.  I was curious.  In general, are ni-rod repairs as strong or stronger than the base metal?Tony
Reply:Hello Dave,Thanks for the info.  No, I didn't block off the exhaust ports.  In fact it didn't even occur to me.  I should have.  If these had been intake ports, I would have instinctively done so.Tony