Attn: Castweld and others. Cracked iron block questions!

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So a good friend of mine bought a boat last fall with a known cracked block. 85 Chaparral 198XL for those of you interested. He got it cheap enough due to that.Anyhow. Not knowing the extent of the damage and hoping it was minor or just a freeze plug or two, he pulled it apart recently. Found some pretty severe damage that is definitely not worth fixing considering how easy it will be to find a replacement block. The engine is a Chevy 3.8L/229ci 90degree V6. Essentially a 305 with two cylinders lopped off much like a 4.3L is to a 350.However, as an exercise in what is POSSIBLE with todays knowledge and technology I was interested in how some of the cast-repairing pro's on this board would approach damage like this, and if they would even attempt to repair it. Naturally as with anything cast my first instinct was massive preheat in the oven and NiRod. Then I started thinking as this is non-structural mostly maybe brazing it would make more sense? Powder welding is interesting but I have no experience. If it was an external crack I don't think I'd have any issue just V-ing it out and JB Welding it to be honest! But a little leak into the boat is not nearly as catastophic as a leak INTO the engine...Points to Consider:For the sake of this example, it is a marine engine with an open cooling system, you should see no pressure in the water jackets. Of course you can't call AAA for a tow out on the lake either... The crack does extend up into the deck surface of the block on both sides but not anywhere near the combustion chambers.Attached are pictures. Discuss. Attached Images
Reply:Well from the perspective of the engine manufacturer, I would suggest O/A fusion welding with CI filler and flux, Torch brazing, or Spray Welding (actually brazing). Of course it would depend on the exact location of the failure and surrounding parts. Pre and Post heating (slow cooling) a must with welding or brazing. I would avoid ANY electric welding as we have seen too many failures of the surrounding area due to temperature shock even with pre-heating.
Reply:Toss it.  Not worth the time, effort, and expense to try and fix that much crackage.  IMHO.  Which is what you already said.    The best laid schemes ... Gang oft agley ...
Reply:duct tape
Reply:As you have stated, I do believe that a repair is possible. Some of the things I would want prior to any repair are:Material identification. Positive identification and CEFull volumetric NDT inspection. Most likely 100% RT. From there you would be in a much better position to take appropriate steps. Until then it's just a best guess."Religion is regarded by the common people as true, by the wise as false, and by the rulers as useful." -- Seneca the Younger
Reply:or if your lucky enough to have all the engineering drawings and stress models already.............
Reply:Damage is just too severe to make this even worth debating.  Your odds of missing something that needs repairing, or getting a bad spot in all that repaired surface make this one impossible to succeed with under anything approaching a reasonable amount of time and expense.(yes, you could make some kind of super lost wax mold of the block and then re-cast it whole.  Or you could slice it into 1" thick sections, repair all the damage and then reassemble with long, strong bolts from the oil pan all the way up through the block.  But you'd never spend the time and money to do either of these things, so why even debate it?)Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:This is a low-performance motor. 170hp rated. That in mind for what it's worth, my focus on the repair would be on creating a water tight repair rather than an as-original-strength repair. There is one head bolt directly above the crack. That's the most load bearing point in the area. Being that there is a lot of head bolts per cylinder, and the low performance nature, that may be a non-issue? Considering the forces the expanding water must have put on that point to cause said damage, I would not be surprised to find additional cracking or potentially even damage to the cylinders. But at this point I have not seen any. Would take a full magnaflux really to find out for sure.The way that the iron pushed out of the block like that means there is definitely some cracking inside of the water jacket that can't be seen. I think I'd prefer to pull that whole piece out and re-fit it if I'd attempt to fix...I'm not surprised by the number of people who immediately say it can't be fixed. I would have thought the same thing myself if not for reading some of Castweld's posts and also looking all over the internet at other information. The most interesting (and kind of expensive) was this Lock-n-stitch system. Uses some really neat bolts that actually pull the crack together. I didn't get it at first but basically you drill a hole right into the crack, and tap it with a special tap, then thread in a break-away bolt. The threads have a relief cut in them which allows them to hook onto each side of the crack and pull it in. Supposed to be as good as new when you're done. No welding, brazing, sealing, etc. Completely mechanical. No way I'd spend $300 on bolts for a $100 block though. Link to some repair examples. Has an OMC Boat enigine with freeze damage which put a hole right in the side! http://www.locknstitch.com/RepairExamples.htmBut the point is that it really makes me wonder if brazing a repair like this is completely out of the question? The LocknStitch guys hate welding is seems, for good reason I guess.Edit: And yes, I am being a bit of a Devils Advocate for the sake of discussion on the matter. It seems cast repair is as much the stuff of legends as it is a science. Everybody has their own beliefs and potions!Last edited by chicksdigwagons; 03-31-2009 at 08:52 PM.
Reply:The question you have to ask yourself is would you spend 50 dollars for new heels and soles on a pair of shoes you bought for 15 dollars?  There is no doubt you will find a shoe repair that will take your money if you look around long enough.
Reply:Originally Posted by lotechmanThe question you have to ask yourself is would you spend 50 dollars for new heels and soles on a pair of shoes you bought for 15 dollars?  There is no doubt you will find a shoe repair that will take your money if you look around long enough.
Reply:If you read all of the lock-n-stitch website on welding, you will notice that they dont like ELECTRIC welding, however they O/A weld ( not braze ) the castings. Their bolting method works OK in given situations, we tested it here at work however and didnt find it acceptable for our block repairs.
Reply:How would I repair it?? ok I would use braze welding however first I would have a machinist collect all the data he could in terms of tolerances and dimensions for cam follower tubes, alignment tolerances of camshaft bore holes as well as cylinders.    After that the block would have to be completely stripped and degreased.  To ensure no cracks are missed you would have to pay for at least two magnaflux inspections.  All cracks would have to be vee prepped and finished with a carbide burr.  Complete gaps would have to be inspected and a decision would have to be made in terms of finshing the fracture and resetting or just filling the crack.  You would have set up a muffle furnace with multiple thermalcouples located at key areas and preheat for several hours.  Consult tables and charts to reach optimum temp and heat soak.   Uncover a section at a time and torch braze repair.    Once it is all done a controlled cooling rate will have to be determined.  At room temp the casting would have to get a visual inspection then another magnaflux or die penetrant exam.  Ultra sonic or even X-ray would be a consideration.  If you don't have any repairs you then turn it over to the machinist who will machine the block completely and rebore the cylinders and bearing bores.  I am told there is a local guy who does magnesium alloy gearbox cases from Sikorski helicopters.  The complete repair up to certification is over ten thousand dollars.  New gearbox price is over 20 thousand.  Those are prices I was told about in the mid nineties.
Reply:Chicks,I think you are right to try to repair it.  What could it hurt? besides the pocket a little?  I would suggest brazing.  All you need is about 800 degrees. I might try welding the upper part where it comes in contact with the head area.  But even that might work with brass.  I wouldn't use those flux coated rods though. I'd buy a can of dry dip flux and use it with bare brass rods.  I thin you'll see a better result and get better sealage.  Get the engine magnafluxed first to see how far those cracks extend beyond the visible spectrum.If it was a little crack, I'd suggest using grits...It works.Esab Migmaster 250Lincoln SA 200Lincoln Ranger 8Smith Oxy Fuel setupEverlast PowerPlasma 80Everlast Power iMIG 160Everlast Power iMIG 205 Everlast Power iMIG 140EEverlast PowerARC 300Everlast PowerARC 140STEverlast PowerTIG 255EXT
Reply:I see this a few days old but I'll throw in my 2 cents.I use Lock N Stitch, this could be repaired but for cost of materials (you supply labor) you could get another block cheaper. From pic and past experiences the cracks that go through at an angle / (not 90 degrees) can be tough to repair using LNS method. After repair get 3/8 or 1/2 plate and cut to shape of head gasket without water jacket holes. Drill bolt hole pattern, then cut 3/16 or 1/4" neoprene sheet material to gasket shape. Bolt to block. Remove water pump, cut block off plate to fit water pump inlet on block, drill, tap 1/4 pipe and plumb in air regulated to 30 psi. Spray soapy water all over to test for leaks. Oh yea visual check outside of block by core plugs first, ice likes to crack these areas also. Take a look at intake manifold water passage also, as well as other engine bank. while you are at it the water cooled exhaust manifolds and elbows will ice crack. A fellow sent me a numbers matching big block chevy (bare block) truck frt from Atlanta with a ice crack for repair. The crack went over the deck like yours but the crack was only about 6 inches long. Did what I described above and sent it back to him. He called about a year later giving praise for repair and we discussed repairing some old chevy heads. It works.Braze would make better repair but, strip block bare, remove cam brgs, core plugs, galley plugs. Heat to 700 degrees weld at temp. If you try without heat you will end up with scrap. After this much heating, the bronze will require about 1800 degrees to stick, you will have some serious machine work to do. Deck block, bore cylinders (cyls next to weld WILL go out of round!), check crank line bore, cam bores, and the lifter bores next to weld may need bushing. If you price machine work this would be cost prohibitive. I like to joke with customers when they ask "can this be welded", I say well yes but I don't know if you can afford machine work and parts. As you can see pinning it- Lock n Stitch or Irontite wouldn't require machine work, new pistons, cam brgs, ect.OK now cheapest way. NI rod. A lot of people are going to complain here but...Drill holes at ends of crack, grind casting clean the width of bead over the crack, weld 1/2 inch- stop- peen immediatly ( I use a needle scaler)  do not weld again unless you can hold hand on previous weld. Always start at end of crack and at some point weld from other end to meet in middle. The problems are going to be hand grinding the deck flat enough not to leak, and keeping metal and grinding wheel dust out of engine. Any of that stuff stays in engine will wipe out oil pump and bearings real quick and damage everything else inside! I would plaster epoxy all over the weld between the deck and lifter bores. Done "cold" it shouldn't distort lifter bores and cyls much, but check anyway.I could go into more detail if needed. I type real slow but weld real fast!Peter
Reply:On the nickel rod........  Is the cold start, and getting hotter as you progress part of the solution?  The hole you drilled would act like a hinge to allow the hotter end of the weld to contract?"Any day above ground is a good day"http://www.farmersamm.com/
Reply:I see this a few days old but I'll throw in my 2 cents.I use Lock N Stitch, this could be repaired but for cost of materials (you supply labor) you could get another block cheaper. From pic and past experiences the cracks that go through at an angle / (not 90 degrees) can be tough to repair using LNS method. After repair get 3/8 or 1/2 plate and cut to shape of head gasket without water jacket holes. Drill bolt hole pattern, then cut 3/16 or 1/4" neoprene sheet material to gasket shape. Bolt to block. Remove water pump, cut block off plate to fit water pump inlet on block, drill, tap 1/4 pipe and plumb in air regulated to 30 psi. Spray soapy water all over to test for leaks. Oh yea visual check outside of block by core plugs first, ice likes to crack these areas also. Take a look at intake manifold water passage also, as well as other engine bank. while you are at it the water cooled exhaust manifolds and elbows will ice crack. A fellow sent me a numbers matching big block chevy (bare block) truck frt from Atlanta with a ice crack for repair. The crack went over the deck like yours but the crack was only about 6 inches long. Did what I described above and sent it back to him. He called about a year later giving praise for repair and we discussed repairing some old chevy heads. It works.Braze would make better repair but, strip block bare, remove cam brgs, core plugs, galley plugs. (gouge completely)  Heat to 700 degrees weld at temp. If you try without heat you will end up with scrap. After this much heating, the bronze will require about 1800 degrees to stick, you will have some serious machine work to do. Deck block, bore cylinders (cyls next to weld WILL go out of round!), check crank line bore, cam bores, and the lifter bores next to weld may need bushing. If you price machine work this would be cost prohibitive. I like to joke with customers when they ask "can this be welded", I say well yes but I don't know if you can afford machine work and parts. As you can see pinning it- Lock n Stitch or Irontite wouldn't require machine work, new pistons, cam brgs, ect.OK now cheapest way. NI rod. A lot of people are going to complain here but...Drill holes at ends of crack, grind casting clean the width of bead over the crack, weld 1/2 inch- stop- peen immediatly ( I use a needle scaler)  do not weld again unless you can hold hand on previous weld. Always start at end of crack and at some point weld from other end to meet in middle. The problems are going to be hand grinding the deck flat enough not to leak, and keeping metal and grinding wheel dust out of engine. Any of that stuff stays in engine will wipe out oil pump and bearings real quick and damage everything else inside! I would plaster epoxy all over the weld between the deck and lifter bores. Done "cold" it shouldn't distort lifter bores and cyls much, but check anyway.I could go into more detail if needed. I type real slow but weld real fast!PeterForgot the powder thing. Follow braze procedure. Powder not needed here because not in chamber. I would use bronze because of cost.
Reply:Originally Posted by farmersammOn the nickel rod........  Is the cold start, and getting hotter as you progress part of the solution?  The hole you drilled would act like a hinge to allow the hotter end of the weld to contract?
Reply:Oh and pics look like 4.3, if bore is 4" its 4.3.Peter
Reply:Originally Posted by castweldDon't know about the hinge thing, but it will pull the crack together.NEVER weld to an end, weld from an end. If you weld to an end crack will form and keep going as long as you chase it.Peter
Reply:I just learned something and I have been welding for a long time, but probly will not see any frozen engine blocks here in So.Fl.  I have welded cracked blocks when I had a Shop in Mass.and always had good luck, just preheat and only weld 1/4 inch at a time let it cool 10/15 seconds peen  weld again ,worked for me. finished it off with magic stick,a graphite and sulphur product about 3/4nch round ,came in 6'' lgth to fill pinholes if they were any . Thats my 2 cents worth , but I wouldn't waste my time with that one. To much work.  Jim