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Discussion Starter · #1 ·
I have a 305 small block with a crack on the driver side seam near the 5 & 7 cylinders. Water will pour right out even with it not running. Otherwise, the engine runs fine! I was wondering if you could safely use a product like JB Weld to seal it up. Obviously, I wouldn't run the engine hard, but it would be nice to have a working spare to get around with when needed.
 

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Magisnyc,

What are you calling a seam? If the leak is between the head and the block maybe a new head gasket would fix it. If the block is cracked they can be welded. You will need to find an experienced welder who can weld cast iron. I had one done a long time ago and it ran for years with no problems. One issue might be cost, the welding could be more than the engines worth.
 

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Discussion Starter · #5 ·
The crack is basically where the side wall of the block meets the top deck of the block. The cylinder head gasket is fine.

I got the car with the cracked block and was planning on throwing it away anyway but when I heard how good it was running - despite the water pouring out - I was wondering if there was any chance of saving it as an emergency spare.
 

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JB weld is cheap enough to give it a try!
I ran and stockcar for two or three years with a craked block from water freezing when I for got to winterize it.this motor saw 220* plus and never
leaked a drop. cleans the block with a wire wheeled air die grinder and wash withbrake clean a few times and smooth the whole side of the block with the JB weld I put on 2 coats of JB .
I did this with the eng in the car.

I would use the car for any cross contry trips but for a beater around town I think you would be fine ,just check every so often!

good luck!!!!
 

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I heard of a guy with that exact problem doing JB weld, it worked for him.
Pull the rubber gasket out of the radiator cap to drop the pressure on it. We do that on farm equipment that has leaky old radiators.
David
 

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We had a '69 DZ motor that had a schmutzed crack revealed by hot tanking. Whatever it the stuff was, it was unaffected. It passed a pressure test, got rebuilt, stuffed in car. Ran great; never leaked.

You do need to stop the crack from growing. Generally drilling a hole at each end does it.
 

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I suggest you do NOT try to have the block welded. I lost a fully prepped, 427 4 bolt main block that way once. There was a small place between the lifter bores that seeped a little coolant, I tried to have it welded and a giant crack opened up. Bye bye block! Just after that happened, I found an old magizine article that suggested you repair this common problem on BB Chevy engines with, yep you guessed it, JB WELD.I believe a cast iron block must be heated almost red hot to be welded sucsessfully. Clean it up real good and try the goo!

Harlan.
 

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I had a 350 freeze up and crack the water jacket in a "Y" shape. I pulled the motor and nickle welded the crack with the engine fully assembled. I had a slight seep when I got done that a tube of Alumaseal took care of. I sold the car 2 years later and it still didn't leak.
 

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we use alumiseal on the farm and it works well. I also used KW block sealer, you mix it water and dump it in the radiator, run the engine, then drain it out.
I got an extra year's use out of a bad block in a John Deere that way.
The block corrodes where the lower end of cylinder sleeves seal to the block.
anyone know where I can find a good used engine for a 2510?
David
 

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I've heard of successful block repairs with JB Weld, But, I've used the stuff myself, Tried once on a Hydraulic line (the metal fitting on the end-expensive little hose so tried to fix first), and the stuff would not hold, It wasn't high pressure either. So, I'm not going to stand by it working for you. You'd just have to give it a try (And keep an eye on it-Dont go on any long road trips).
 

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I didn't want to drill holes in my new GM cast aluminum valve covers to mount a baffle for a PCV valve and a friend recommended J-B Weld. I tried a few test pieces (aluminum to aluminum) and then used it to mount the baffle in the cover. The test pieces snapped apart too easily to make me comfortable about leaving the baffle J-B'd and without screws to hold it.(yes the mounting surfaces were roughed up) I guess J-B has some good uses, but I don't think I could trust it? At least not too far from home.
Jim
 

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I agree this is not a permanent fix and could fail at any time. But for running around locally it might be worth a try. We have a tractor block patched with "Liquid Steel" and it's going on 30 years! JB weld would be much stronger than that stuff.
David
 

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I have stripped out spark plug hole in my Cavalier. I heli-coiled it, and that stripped too. I then JB-Welded the plug in, and I've put 10,000 miles on it sense then. And that's got to be one of the hottest spots on the engine. Try the JB weld, might be a cheap fix
.
 

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I had a chip in my block near an oil gallery plug right against the oli pan. It was pouring oil out the bottom. I patched it with JB Weld. That was about 12K miles ago. Still no leaks. I run it at the track, put it on the dyno and just got back from running the Long Haul on the Power Tour.
I applied 3 thin coats with 24 hours of drying time in between. I have since painted over it so that it is not really noticeable.
 
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