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J-B weld on engine block


Buick35
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I'm not sure but it looks like I have a small pin hole or hairline crack on my block around my #1 cylinder. I just put on a rebuilt water pump and thought that might be leaking but now there's a wet spot where I mentioned.Short of having it welded is there something I can use to stop the leak? I thought j-b weld but I think it has to be completely dry.Any thoughts please.Greg

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Your choices are to stitch it out of the car, or live with it. Trying to cover it with epoxy may work short term, but thermo cycling will eventually cause it to fail. It could be a crack, or a casting flow seepage. Believe it or not, running straight water may make it rust and close up. The more you mess with it, the more you will regret it. 

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Early Jeep flat fours are notorious for hairline cracks near the distributor on the passenger side of the block.  

 

Most Jeep guys lightly grind the area to get it 100% shiny clean and that leaves a toothy surface that will allow the JB to bond perfectly and grip good.  I did this to my son's 46 CJ2A well over 2 years ago and it's still leak free here in New England with air temps from upper 90s down to zero degrees in winter.  It does have antifreeze which as some people know, that can tend to weep compared to just water.  It does not weep at all.  This is the most used vehicle on his tree farm and is used every few days.

 

Yes it needs to be totally dry.  Drain the system and preheat the block by running or propane torch, to make sure the crack is dried out. Let it cool to normal air temp, then use the JB.  

 

Disclaimer on what type of cracks:  If a crack is vertical and goes up to, and underneath the head gasket, then JB won't prevent it from leaking at that gasket area.

 

i'd wash the whole suspect area with degreaser a few times, get it dry and see exactly what and where it's leaking, (before trying to do anything).  Sometimes leaks are not where we thought they were.

 

 

 

 

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If it’s a non-pressurized system you can have a weep, and no issues.

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You can do a lot of stitching with the motor in the car if you can get a drill in there.  I did our 40' Buick last year.  Many hours of fun.  

This car was stitched at some point but they left 1/4" gaps without pins and smeared JB weld over the entire thing.   

DSCF4414.JPG

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