Cracked Block.....Repairable?
05-26-2008, 04:02 PM
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Cracked Block.....Repairable? O.K. as you can tell, I got a HUGE problem here. I saw what I thought was a small scratch on the rear of my block, on the machined surface that the rear cover bolts to. Well, I could feel it with my fingernail, and it looked kinda "jagged". Wow, I thought to myself, was this a small crack? Sure enough, I got a really good light on it and upon looking through a good magnifying glass....Bingo, it is a CRACKED BLOCK!!!
I have Darton Sleeves installed in my block and the block is a '98. In short, I got a LOT of money in it!! When Steve Dimirjian did these sleeves, he told me that the rear of the early blocks have 2 oil galleys that run from front to rear, like the newer blocks, but what they DON'T HAVE is a "connecting galley" that ties them together, like the '99 and newer style blocks have. He told me he could machine in this "connecting galley" and we'd be good to go. This is where the crack is. It is barely noticeable and runs from (And totally through) the rear machined surface to the small oil hole that runs up to your oil sender. It can then be seen again 180 degrees around to the other side of this "oil sender" hole, where it then runs down towards the center of the block for maybe another inch. I bought this block used, so it COULD have been there when I bought it. But that is hard to believe because I can't help think that Steve would've seen it and told me about it. I was getting no oil in the coolant or vice-versa. I was just starting to put the motor back together, but now find myself stopped in my tracks. What should I do? The motor didn't leak any oil, even though this crack IS under 70lbs., or thereabouts, of oil pressure, whenever the motor is running. I am wondering if you guys have had any experience with heli-arcing these blocks, or trying, in some other way, to repair them? Or, should I try and salvage the Darton sleeves and sell them and put that money towards a new LS7 block, or what? My son, who has a masters in mechanical engineering, stopped by for a look see, and he agrees that it is a crack. He is suggesting that since I have it nearly back together, I should go ahead and finish it up. He feels that the rear cover does add some small measure of strength, like a "girdle", as does the bellhousing, when it's bolted up. He thinks that when I have it all put together, instead of bolting it into the car, I should take it to W2W, or similar tuner shop, have them strap it to the dyno, and show it no mercy for around a half hour or so. His feeling is that if it leaks no oil, and the crack shows no further advancement upon a post run inspection, I should bolt it into the car and run it 'til it drops!! What do you guys think?? Please help!!! I value your opinions, guys. Thanks.
I have Darton Sleeves installed in my block and the block is a '98. In short, I got a LOT of money in it!! When Steve Dimirjian did these sleeves, he told me that the rear of the early blocks have 2 oil galleys that run from front to rear, like the newer blocks, but what they DON'T HAVE is a "connecting galley" that ties them together, like the '99 and newer style blocks have. He told me he could machine in this "connecting galley" and we'd be good to go. This is where the crack is. It is barely noticeable and runs from (And totally through) the rear machined surface to the small oil hole that runs up to your oil sender. It can then be seen again 180 degrees around to the other side of this "oil sender" hole, where it then runs down towards the center of the block for maybe another inch. I bought this block used, so it COULD have been there when I bought it. But that is hard to believe because I can't help think that Steve would've seen it and told me about it. I was getting no oil in the coolant or vice-versa. I was just starting to put the motor back together, but now find myself stopped in my tracks. What should I do? The motor didn't leak any oil, even though this crack IS under 70lbs., or thereabouts, of oil pressure, whenever the motor is running. I am wondering if you guys have had any experience with heli-arcing these blocks, or trying, in some other way, to repair them? Or, should I try and salvage the Darton sleeves and sell them and put that money towards a new LS7 block, or what? My son, who has a masters in mechanical engineering, stopped by for a look see, and he agrees that it is a crack. He is suggesting that since I have it nearly back together, I should go ahead and finish it up. He feels that the rear cover does add some small measure of strength, like a "girdle", as does the bellhousing, when it's bolted up. He thinks that when I have it all put together, instead of bolting it into the car, I should take it to W2W, or similar tuner shop, have them strap it to the dyno, and show it no mercy for around a half hour or so. His feeling is that if it leaks no oil, and the crack shows no further advancement upon a post run inspection, I should bolt it into the car and run it 'til it drops!! What do you guys think?? Please help!!! I value your opinions, guys. Thanks. 
05-28-2008, 07:52 PM
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A cracked block is nothing to sneeze at, regardless where the crack is located. I suggest contacting an expert like Katech or Race-Eng Development for solid advice.
