The Stovebolt Site Forums The Shop Area Engine Shop JB Weld Repair

I have a 248 that appears to have a crack in the block. I'm assuming it does as there seems to be a couple of pieces of sheet metal epoxied onto the side of the block and there a little rust coming out of that area. When I pry/grind/chip these "patches" off I guess I'll see what I actually have. I've been reading about several folks fixing block cracks with JB Weld. I gather you have to grind out the crack with a grinder and then fill in the JB. My question is how deep and wide do you grind out the crack? Also, has anyone ever documented this type of repair with photographs? Just wondering how far to go with the grinding, I don't want to over do it.

Cracked block is still a cracked block. Just the same nothing tried is nothing gained. J B Weld makes I believe two kinds of filler. One is more runny thay the other and is more durable. I did use the stuff on an exhast manifold leak between the manifold and the block. To my suprise it is holding up quite well. This is on a John Deere tractor and would other wise be quite expensive other wise to repair the correct way. The tractor dose no hard labor but non the less it's help up well for the past the past year.
If you try it I would clean & grind only enough to make sure the crack is clean. Be sure to let us know how it works out for you. Good luck !!

And do not under estimate the power of liquid glass.
Seen many vehicles avoid the scrap heap juiced up on that stuff, with no tools needed.
I would have never thought it myself.

Yep, done it myself , had to use a strip of masking tape to stop the stuff flowing out of the crack, once it was cured the tape left a good texture on the "weld".

What is "liquid glass"?

sodium silicate, main ingredient in muffler repair cement

Bill

http://www.ytmag.com/ttalk/messages/84244.html
http://www.iccindia.biz/irs.html
THe stuff is nasty. Good luck

A necessary step in sheet metal and plastic repair is to drill a relief hole at each end of a crack, to keep the crack from progressing. I've successfully repaired cracks in radiator headers and tanks that way. (I know it goes against the grain to drill a hole in something that already leaks, in order to repair the leak, but the technique works.) I've not tried that technique on cast iron, but since cracks tend to progress with time, I think that method is worth considering, especially since you are considering a cement-type filler. Since you are planning to grind the crack to open it up, grinding a radius at each end would serve the same purpose as a relief hole.

Let us know how it goes.

Harvester

Although I myself repaired a crack successfully with JB Weld in a transmission, I don't think I would trust it with an engine block crack, no matter how good the stuff is. If you think it's salvagable, then see if someone will weld it. Yes, you can weld iron. The block needs to be preheated in the weld area first. But if there's rust coming out, I really don't know how you would clean up the crack, since it's obviously not fresh.

I think it's time to go shopping for a new engine my friend.
These guys sell aluminum Stovebolt heads, replacement blocks, EFI, etc., etc. Check them out and see how much it would cost you to at least get a new block. And maybe they have complete crate motors:

http://www.waynemfgco.com/frame.html

Also, I have found 292 Stovebolts on the internet in the form of crate motors. They weren't very much either, I think a few grand for a stock rebuild crate engine. I don't have that link with me, it's at home. But I'll try to remember to get it and post here later.

Thanks for the info. As for getting another motor, it's not in a truck right now and is just a motor I bought to fix up. I figure the worst I can do to it is completely ruin it but no biggie if I do (only cost me $100 and I can easily make that back selling some of the parts if I have to go that route). On the other hand, if I can fix it then I may have to talk Momma into a truck I can put it into. Anyway, since it's already in the garage half apart I guess I'll give it a shot and see what happens.

That is a 700 pound hunk of iron, and is huge enough to make it a real maneuver to take in and out of an AD truck. Why wouldn't you just want to do the job once? I'm afraid if you do it and it fails, you'll be doing it again, wishing you had just done it once with the last engine you'll ever need.

Bring that up to your wife, and she might agree.

You had me there, Bill, I always knew it by the name of water glass. My grandparents used to use it to preserve fresh eggs.
Bob

I have brazed, welded, and epoxied cracked blocks. Welding with nickel-alloy rod is the best, but also the most difficult fix. The crack must be stop-drilled at both ends, V-ground along the entire length of the crack, and then welded in beads of no more than an inch in length, after pre-heating with a torch. Don't get the block red, just hot enough to radiate a pretty good bit of heat to a hand held near the repair. Weld a short bead, then peen the weld for several minutes with the pointed end of a slag hammer to stress-relieve it. Heat again, weld another inch, peen- - - -repeat as necessary. Overlap each bead a little to minimize the possibility of creating multiple seep leaks at the bead starting and stopping points.

I strongly reccomend perfecting this technique on a junk block before doing the real job! Experiment with AC and DC current, ground polarity, and heat range to find the technique that gives the smoothest, least porous weld. Different block alloys require different approaches. A slag pocket can ruin your whole day! Once you're confident in the strength and continuity of your weld, the outside can be cleaned up by grinding, but not too deep. Don't try to hide the repair by grinding it completely smooth. Cool the block thoroughly before dressing up the bead.
Weld 10 seconds- - - -peen 10 minutes! Keep the block hot during the welding procedure, then bury it in sand or layers of some sort of insulation to cool it down slowly. If it goes "TINK!" during the cooling process, look for another crack, right alongside the weld bead. It happens! Good luck!
Jerry

I've done a JB weld repair on a 3 - 4 inch crack on the block (in place), and it went just fine and is holding up great. Sorry, no worthwhile pictures. As mentioned above, I drilled out the ends, vee-ed the crack, and really cleaned the surrounding area well. I followed a few other suggestions that the friendly stovebolters came up with. Of course the coolant was drained, and before applying the JB weld I preheated the crack, and I even attached the shopvac to the radiator so the JB weld was sucked into the crack.

At trick I learned long ago is to shut off the oxy to the torch and apply a good coating of carbon to the object to be pre-heated and then dial in the oxy and heat. If I remember correctly, carbon burns at 800 degrees and you can tell how quickly it disappears how hot and evenly heated your part is. As the part gets hotter it takes less and less use of the torch to make the carbon film disappear.

I haven't done this in 30 years but I know it worked back then.