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block crack, please help

J

jeepnuts311

NAXJA Forum User
Location
Atlanta, Georgia
hey all,

swapped motors and i had a coolant leak, suspected the head gasket. i tore down the intake side of the motor to start getting ready to do the gasket. i found two cracks just above the freeze plugs which appears to be a factory seam all the way down the block. there is a leak above freeze plug 1 and freeze plug 3.

crack.jpg


i plan on JB welding the crack since this motor is supposed to hold me over til i finish the stroker, but i am concerned since it seems to be a factory "seam" in the casting. please help

-Tim
 
jeepnuts311 said:
hey all,

swapped motors and i had a coolant leak, suspected the head gasket. i tore down the intake side of the motor to start getting ready to do the gasket. i found two cracks just above the freeze plugs which appears to be a factory seam all the way down the block. there is a leak above freeze plug 1 and freeze plug 3.

crack.jpg


i plan on JB welding the crack since this motor is supposed to hold me over til i finish the stroker, but i am concerned since it seems to be a factory "seam" in the casting. please help

-Tim
Click to expand...
I had a similar crack except it went from one freeze plug to the other. It was on an AMC gremlin a million years ago. Basically the same motor though. 258 slant 6. Any way I put some KW block sealant ( I think that was the name of it ) in the cooling system and it held until I unloaded it.
Man that is a long story. ( Short Version)My gremlin blew up from lack of H20 in the Nevada desert in the middle of the night and I hooked up with a guy with a flat bed who brought me up to Boise to fix the Gremlin up here and I haven't left since over 2 decades later. 3 kids and 2 grandkids later. Funny how life has its little surprises for us. Being from the Bay Area, Idaho was probably the last place I would of expected to land. But I landed, loved it and stayed.
Ok back to your thread. I'll research and see if I can't find it somewhere on-line and PM you a link.

PM sent !
 
Last edited:
Drill a hole on either end of the crack to prevent it from spreading and have it brazed, run some Porter Seal thru it to help seal it from the other side before you do.
 
just my 2 cents, leave coolant cap half loose so It doens't build pressure, might get you by for a bit.
 
Drill the holes and braze as somebody suggested.

There's also a technique called "lacing" for cast iron which involves drilling/tapping along the crack, threading bolts in the holes, breaking them off, and going back inbetween the bolts along the crack with more threading and bolts.

This is done to large industrial cast iron machinery when it can't be kinetically welded. Doesn't really hold anything together but it seals and keeps the crack from spreading.
 
alright, i buttoned the XJ back up after the JB weld cured and i filled her up and ran it. for about 5 mins everything was peachy, but once it got up to operating temp, there was a very very slow leak from the rear most crack (it was slowly wetting the block, but not dripping) and when i shut the jeep off, the front crack started to cry a little bit too..

somehow the water found a small passageway behind the JB

will that block stop leak fluid crap help?

-Tim
 
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