Welding a Cracked Water Jacket

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Hi,I'm getting ready to weld a tractor engine block this weekend.The crack is about 10" long, I plan on drilling the ends, then the rest of the crack with 1/8" bit then v-out the crack,use 3/32 softweld 99ni rod,heated to 300deg.f. in a rod oven.Lincoln says the area should be heated to at least 500deg.f.My questions are what would the optimal heat be?around 750?My other question is what is the best way to weld this? weld an inch,peen,go to the end weld an inch peen go back to the front skip an inch then weld an inch etc...(skip around) or weld an inch peen,weld an inch peen etc.TIA for any ideas.
Reply:The following is my take on the situation base on what I've read on the subject, not from personal experience.What you're saying about skipping around and peening each segment makes sense, since this should help minimize the tensile stresses of the weld pulling on the somewhat brittle engine block material.A small short weld won't pull as much as a big long one.Peening counteracts the tensile stress in the weld, relaxing the stress, and even imposing compressive stress.The preheat is intended to slow down the cooling rate to prevent brittle martensite formation in the heat affected zone (HAZ) next to the weldPreheating a fairly large portion of the block, (the entire block?) is probably very important to reduce sharp differences in thermal expansion stresses produced by welding.  Slow cooling is probably a good idea as well.A very "soft" ductile weld filler such as 99 nickel is another key to preventing cracking in this weld repair.  The ductile filler can deform easily under the contraction stresses of welding and thereby prevent the less ductile block from cracking.Hope to hear how it comes out for you.
Reply:Before you try welding, maybe you should look in to other repair methods?  Stitching is an interesting process.  www.locknstitch.com has a ton of info with some great repair examples.Here is an example of a repair of a cracked water jacket on a Cummins 5.9Lhttp://www.locknstitch.com/Repair%20....9%20block.pdf
Reply:Cool link 76GMC1500_________________Chris
Reply:try to slow the cooling process as much as possible also.on small peices ive used buckets with cat litter or vermiculite(from gardening  supply) got it warm on or near a fire or stove then soon as done welding hit entire peice(least a big portion of it) with the torch again then buried it in the warm vermiculitenot sure how ya would go about that with a complete block unless its totaly dissasembled and ya dont mind re cleaning it.I quess u could hit with torch let cool a bit hit with torch a little less let cool a bit  or make a pad oughta welding blankets to try and perserve your heat but itll make for a long tense few hrs!!! If the crack is minor u may be able to get by with a good ceramic sealer(not hte cheapy radiator repair stuff at the local pep boys) if ya got a a good auto place ask em if the have some moroso ceramic engine sealer
Reply:Hello,The reply you received re;Lock N Stitch is the route I would suggest you travel for in chassis repair you have described. Gary Reed (owner of L N S) has a very reliable/dependable process. I weld damaged-cracked blocks and heads made of both cast iron and aluminum daily. With the block in the chassis and dirty to boot not to mention the area needing repair will probably not allow for any type of favorable positioning i.e. flat, like you had it on a welding table you will be doing battle with not only the dirt gremlin but gravity as well. If you should choose to do the repair with SMAW or Tig then as you have suggested use 99% nickel and try to heat the area (500f.) you will be repairing several times letting it cool in between each heating to allow the dirt in the crack/casting to pull out and dry the contaminants before you preheat to weld.Brush well with a stainless wire brush. After you vee the area to weld take a oxy/act torch with a slightly carburizing flame and pass it over the vee'd out area and you will see some very small sparks jumping off the casting, the sparks are the ferrites that if not removed from the weld zone will cause you fits in the weld pool at the boundary/joint. I try to only preheat a minimum (250 deg.F) and strike/start the arc on a piece of scrap and then move onto the block this will help with contamination and flux inclusions. only go about 1" at a time and peen the area and move to another area away from where you just finished to keep the heat concentration to a minimum.Remember whichever method you choose be prepared to deal with the foreign material (grinding/drilling debris) will most likely get into areas you want to protect so that when you through you haven't allowed the debris to get into the crankcase or cooling system. I hope this helps you a bit. Let me know if you need any other help. Let us know how this turns out.Ric
Reply:Here's an update on my block welding,I could'nt use the pre-heat method,The casting was too thin and started to crack at about half the preheat temp.drilled and ground the "new" cracks,then went with a real slow method.I just started with small beads about 5/16"just until it woud pool then stop.tap,tap,tap...go to the other end,same process over and over grinding weld smooth letting cool after a few tacks too keep the heat down.seems to be good.I don't know about my welding,but my "zen"breathing has deffinitely improved  .
Reply:Make sure you line bore the block and check straightness of decks.You may shift the entire casting with the weld.
Reply:good luck, cast is a finicky creature, but it sounds like you've got it licked
Reply:I have cold welded a few.  Preperation was noted above and is first rate.  Ric Havel has more exp than me.  If the block needs to be taken out, do it now or end up doing it later.  I was taught to back step weld.  One inch in back to the begining.  Peen, cool, another inch in back to first weld........  I was also taught not to use a grinding wheel, chip your Vee or use a carbide bit.Good luck.  Please post pics when done.David
Reply:Originally Posted by 59ih340.I just started with small beads about 5/16"just until it woud (sic) pool then stop.tap,tap,tap...
Reply:I saw a horrific long weld repair in the side of a dozer cylinder block. Owner told me that a welder had repaired it by burning one tack per day, over a couple of weeks. Have you ever seen a “patch” of plate steel, retained with screws?Then there's the old drill and pin program too.edit: Oops, looks like this ground has been covered.Last edited by denrep; 02-22-2007 at 08:26 PM.