Welding/brazing diesel engine block

I have an old log skidder which has a long (around 24 inch) crack line running most of the length of the water jacket which is cast into the block.
It was repaired years ago by the previous owner with JB Weld epoxy and has mostly held, but now the epoxy is giving way and some coolant is leaking out. It would be difficult to get this to a professional for repair due to it's size and weight, although I will look into getting someone to come out to where I am. I have an old 200 amp AC stick welder, a Miller 175 MIG and do not have an Oxy/Ac rig, although I may get one for this if recommended.
I know welding /brazing cast iron has been covered before, but I'm perplexed at how to repair this. First, I assume the block is cast iron. If I weld it with cast iron, high nickel content rod, how could I preheat and slow the cooling down on such a huge heat sink? Seems from what everyone has discussed before, I could crack it worse if I don't do this properly. So then, what about brazing? Would this hold under this application, and how difficult would it be to do? If all else fails, I may just grind the JB Weld down, clean it up and apply more epoxy, but this really goes against my nature. Anyway, sorry for being such a nerd on this one - its just something I haven't encountered before and I don't want to muck it up. Thanks!
John
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Preheating the block with a BIG oxy/aectylene tip and stick welding with nickle rod is the most practical solutions.
A contract welder with his own truck could do it in a few hours, but it will cost about $500 - $800, I would guess.
Since it is only holding water pressure it isn't as critical as other parts of the block. This is a common failure on marine engines.
There are epoxies far better than JB weld.
These guys make some truly amazing epoxies.
http://www.belzona.com /
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Thanks for the help on this, everyone. Sounds like epoxy is the way to go. The Belzona epoxies are hard to find - the nearest distributor is 120 miles from me, but I might be able to find an online source. I hope this works.
John
wrote:

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Doctor John wrote:

If you do find an online source, pass it on to the group. Froogle can't find anybody selling it...
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wrote:

leaking
due
slow
JB
For Belzona products try http://www.dbrassociates.com/index.htm
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Wouldn't it be possible to preheat by just running the engine?
David
Ernie Leimkuhler wrote:

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"quietguy" wrote: Wouldn't it be possible to preheat by just running the engine? ^^^^^^^^^^^^^^^ If you ran it with the coolant circulating, it would not get hot enough. If you drained the coolant, you would probably damage the engine before it got hot enough.
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I initially thought that, but then someone suggested an electric blanket and I know most motors get hotter than those blankets, but...
David - always willing to share his thoughts, even when they are NBG
Leo Lichtman wrote:

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A bit risky with no water jacket.

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| Wouldn't it be possible to preheat by just running the engine? | | David
It seems to me that whatever means get heat into the block will do just fine. If you are capable of warming the entire block up to a nice warm temperature, then you've put lots of heat in, but not all the way to the temperature you need. Now that things are warmer and less likely to suck the heat away, a torch might finish the preheat job, albeit a little bit more localized. The way to think of this is that heat and temperature are not the same. Heat in this respect, is like a tank you need to fill, except it has a leak in it. The leak is the external environment and the rest of the tank wants to have equilibrium of temperature as well, so you have to "fill up" the whole block with heat, all the while overcoming the leaks. Once less of the block and environment wants to suck massive amounts of heat away, you don't have to work as hard keeping it "full." There's the old question about which has more heat, a red hot nail or a bathtub full of cold water. The bathtub has more heat, but the temperature isn't as high. It obviously takes a lot more heat to raise the temperature of the water up ten degrees than the nail.
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I'll add my voice to the Belzona supporters. Throughout my Coast Guard career I watched several really talented shipboard engineers use Belzona products to make some difficult and effective repairs in engine rooms - things that couldn't be welded for one reason or another. Pricey and not easy to find, but good stuff.
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Drill a small hole at each end of the crack. This will prevent the crack from growing any larger.
Grind a small groove [approximately 1/8" deep] along the weld.
Heat the entire block [wrap in electric blanket or build a brick box around it, supply heat via any source]
Heat the weld area with an oxy/acetylene torch.
Weld with a Nickel electrode using a step sequence [start " from the start of the crack, weld 'backwards' towards the start, jump another ' and weld back toward the last weld, repeat]
After each " step, peen the weld surface with a dull point of a chipping hammer.
When done leave the block in the brick box or electric blanket for the rest of the day.
NOTE: All this is probably not necessary for a water jacket, but the same steps can be used to repair leaks in cylinder heads.
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At the risk of repeating myself (and differing in opionion from Ernie), this is exactly the application where cold welding with nickle rod shines. Drill the ends and V out the crack - use a narrow (60 degree) V to minimize shrinkage, and leave the back of the crack connected (you do not want to fully penetrate, getting crap in the water jacket). Use DC-, you should not have a crater (pulling iron into the nickle is not desired) - the manual I'm looking at says there should not be a spray, the metal should fall from the rod in "plops or blobs". Tack about every 2 inches, and then start each new short section on a tack, moving to the cast to lengthen the tacks until the whole crack is covered. Cutting and pasting my own comments from a January 2004 discussion of cast iron repair, with some slight edits:
Use 55 or 99 Ni rod and your stick welder. Weld 3/8 inch, peen the crap out of it RIGHT AWAY, weld 3/8 inch somewhere else on the crack, peen the crap out of it, repeat until done, never get the casting hot. Take a break if you're in danger of getting the casting hot. Very localised application of heat, lots of beating, very quickly, on the nickle to let the nickle move as the weld bead cooled, rather than let the cooling weld bead crack the iron. Keep peening until each bead has fully cooled.
I personally have only done a little bit of this in class 11 years ago. But the guy who taught me did it, and spent the summers teaching NYS DOT and town maintenance welders to do it, as part of the Ag Engineering school's mission to save the state taxpayers money by educating local maintenance workers. As he explained it, the difference between preheating and not preheating was the difference between (for instance) stripping an engine block, finding or cobbling up a furnace big enough to preheat it, welding on it, cooling it, then putting it back togther afterwards, .vs. cold-welding the crack in place, or at least without needing to fully strip the block.
Having both done it and seen it done, I do think it actually works. Welding a stich and goofing off for 15 seconds to find your hammer probably would not work. Trying to hurry the process definitely won't work.
On the other hand, if JB Weld worked for years, cleaning it up and either re-doing JB Weld, or using something a bit fancier in the epoxy line is not such a bad option to consider.
--
Cats, Coffee, Chocolate...vices to live by

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I agree, the trouble it would take to do the job right may not be worth it. Epoxy may be sufficient more 5 more years. Welding it properly will be an all-day job. (A tube of chalk/mastic can be applied in 5 minutes.) There's a fair chance of the crack propagating if proper precautions are not taken. Plus it sounds like you may need to buy/borrow equipment. [Torches, DC welder, etc]
I like loctite for 2-part epoxies. They have a wide product range.
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"Ecnerwal" wrote: (clip) As he explained it, the difference between preheating and not preheating was the difference between (for instance) stripping an engine block, finding or cobbling up a furnace big enough to preheat it, welding on it, cooling it, then putting it back togther afterwards, .vs. cold-welding the crack in place, or at least without needing to fully strip the block. (clip) ^^^^^^^^^^^^^^^^^ This is also why brazing is a very poor choice in an application like this.
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If you are going to repair in place you might try a high tech epoxy as suggested. The other alternative is to use ni-rod and weld relatively cold. You will not be able to preheat the engine block properly if the engine is to remain in the skidder. http://www.twi.co.uk/professional/protected/band_3/jk25.html
The above site gives a good outline on the required preheat. Note temps are in Celcius. You might consider welding it cold as Lincoln outlines. http://www.lincolnelectric.com/knowledge/articles/content/castironpreheat.asp
A 24 inch crack is a long crack. If I was welding it "cold" it would take a full day since I don't put down another 1 inch bead until I can put my hand on the peened weld.
My vote goes for the epoxy repair unless you are going to remove the block, strip out parts and do an overhaul anyway. Randy

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It was somewhere outside Barstow when "Doctor John"

There's no way I'd even try to weld a crack that long.
As the epoxy has held so far, I'd be tempted to either repeast that, or to use something like Oyltite. Although this has no mechanical strength whatsoever, it's a little flexible and so it actually makes a better seal. If this really is just the water jacket and isn't under a mechanical load, then all you need is to make it water tight to a couple of bar pressure.
Another option is to drill the block and bolt a plate patch over it.
If it's a mechanically stressed part of the block, then I'd phone the Metalock guy and have them stitch it.
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I have used Belzona in engine blocks for many years. Belzona Technical Consultants will show you the proper way to use their materials. I have never seen a Devcon, Ciba, JB Weld or any other reo who would show up on the job site to lend technical assistance. Our Allis Chalmers 180 diesel tractor had a problem in the lower cylinder bore. We used Belzona Super Metal to repair the damage which had been caused by electrolysis. The repair is still in excellent condition. The repair was done in 1989. Years ago, I fixed a cracked oil pan on a M-60 tank. The pan was made of an aluminum alloy. Welding was not an option. The crack was drilled, tapped and screws inserted. The screws prevent the metal from moving. The crack was veed out. The surface was roughened and degreased with MEK. Belzona Super Metal with reinforcement cloth was applied to the damaged area. I have never had a problem with an engine, where Belzona was used. Caterpillar specifies Belzona. Must be good stuff. The long term results speak for themselves, Belzona works!
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An interesting post. I'd never heard of it but did a search and came up with http://www.belzona.com and the following info:
With Belzona Distributors operating in over 120 countries, you are never far away from Belzona products and service. Please contact the appropriate Belzona Headquarters based on your geographic location and the lead will be forwarded to your local Belzona Distributor.
Belzona Inc. 2000 N.W. 88th Court Miami, Florida U.S.A. 33172
Toll-Free 1-800-238-3280 Telephone: +1 (305) 594-4994 Facsimile: +1 (305) 599-1140 snipped-for-privacy@belzona.com
Belzona Polymerics Ltd. Claro Road, Harrogate HG1 4AY England Telephone: +44 1423 567641 Facsimile: +44 1423 505967 snipped-for-privacy@belzona.co.uk
=========== snipped-for-privacy@yahoo.com wrote:

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Just use some sealer on it. Make sure the coolent is hot so the stuff dissolves as it should.
John
Doctor John wrote:

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