Cracked Block - JeepForum.com
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post #1 of 17 Old 02-15-2013, 04:29 PM Thread Starter
semperfi1919
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Cracked Block

Well after all the work I have put into the jeep I finally got my seat brackets built and seat installed and fenders built and shocks installed, and was about to take it out for a road test and discovered antifreeze pouring out from underneath, Thought, well just a hose leaking, no big deal, But NO WAY, I discovered the block was cracked, about 6 inches long, on the drivers side just about 3 inches below the freeze plugs, It has had antifreeze in it and has not been ran so I know it didnt run hot, So cant figure out why it cracked, Well guess its time to start looking for the V-8 to install now...


MSG Cooley Sean, KIA Feb 3 2005
1LT Oneto-sikorski,Robert KIA Oct 31 2005
Rest in Peace, gone but never forgotten
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post #2 of 17 Old 02-15-2013, 04:40 PM
BESRK
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Don't feel too bad. My son replaced the radiator on his Comanchee a couple months ago.. and refilled it with straight water.

Got down to 17deg a few weeks ago and put a nice 5" long crack along the driver's side of the 2.5 fourbanger. Since we use that truck as the "shop beater", I pulled the engine, ground a "V" along the crack.. and filled it with JB Weld..

Dropped the engine back in today.. will fill it tomorrow and see how long it holds up.

'80 CJ5 w/AMC360, T176, D44 w/Detroit 4.56, RE 4" YJ lift and 35s..


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post #3 of 17 Old 02-15-2013, 04:54 PM Thread Starter
semperfi1919
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Quote:
Originally Posted by BESRK View Post
Don't feel too bad. My son replaced the radiator on his Comanchee a couple months ago.. and refilled it with straight water.

Got down to 17deg a few weeks ago and put a nice 5" long crack along the driver's side of the 2.5 fourbanger. Since we use that truck as the "shop beater", I pulled the engine, ground a "V" along the crack.. and filled it with JB Weld..

Dropped the engine back in today.. will fill it tomorrow and see how long it holds up.
Im gonna try to put some of the Bars stop leak into it and try that out, I dont think its gonna stop it, then I might try the JB weld, Just wanted to get some play time in it before the engine swap after I find the 350 to install.

MSG Cooley Sean, KIA Feb 3 2005
1LT Oneto-sikorski,Robert KIA Oct 31 2005
Rest in Peace, gone but never forgotten
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post #4 of 17 Old 02-16-2013, 08:17 PM
Cutlass327
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Don't waste your time with Bars Leak.

Rick

1978 CJ5 5.0HO/T177/D300, '86 D30/D44 WT axles, 'glass body, 31x10.5 BFG A/T, TDK galv'd frame - DD and weekend toy

http://www.jeepforum.com/forum/f8/ri...8-cj5-1223197/
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post #5 of 17 Old 02-16-2013, 09:32 PM
lucdog
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Quote:
Originally Posted by BESRK
Don't feel too bad. My son replaced the radiator on his Comanchee a couple months ago.. and refilled it with straight water.

Got down to 17deg a few weeks ago and put a nice 5" long crack along the driver's side of the 2.5 fourbanger. Since we use that truck as the "shop beater", I pulled the engine, ground a "V" along the crack.. and filled it with JB Weld..

Dropped the engine back in today.. will fill it tomorrow and see how long it holds up.
My 258 held up for a year, with the "V" and JB Weld. I was in the same place as the OP's and a foot long. It only started seeping in one 1/2" spot.

OP, I wouldn't use anything but the JB weld. Not the 5 minute set stuff either. The best JB takes 24 hours to set up, so read the label.
The best way is like BESRK said, make sure it's bright metal,clean, and dry. This means draining the block, grinding, and blowing the crack out with compressed air.

IMHO, any other fix will be a waste of time and money.

Bill

1957 WILLYS pickup,
1973 J 4000,
1978 CJ7 DD.
1979 CJ7 360, TH400/Quadratrac.
1979 J20
1980 CJ5 trail Jeep.
1983 CJ7
1989 YJ the CJ to YJ.
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post #6 of 17 Old 02-16-2013, 11:54 PM
82JeepCJ7
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Never put stop leak in an engine.

Clean the crack up real good and grind a V in it as described before. Warm the area up with a propane torch. Put a good bead of JB weld down the crack. Let it harden a day or so. It will last a long time.

We did this on our race car motor on the 2nd night of the season. It lasted the whole season on a 360 sprint car motor.

Beat it to fit, paint it to match!

Wheel, Wrench, Repeat.
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post #7 of 17 Old 02-17-2013, 03:38 AM
RWise
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many moons ago I used a product called "water glass" works well on cracked blocks, (cannot be added to anti freeze) JB weld can work well also. Bars leak, well, ground black pepper works as well or better,,,,,, only you can see the leak, good luck!
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post #8 of 17 Old 03-04-2013, 08:39 PM Thread Starter
semperfi1919
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UPDATE:: Used the grind and pack with JB weld method. Its working. Thanks for the reply's

MSG Cooley Sean, KIA Feb 3 2005
1LT Oneto-sikorski,Robert KIA Oct 31 2005
Rest in Peace, gone but never forgotten
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post #9 of 17 Old 03-04-2013, 10:09 PM
JrTjK
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Quote:
Originally Posted by semperfi1919 View Post
Well after all the work I have put into the jeep I finally got my seat brackets built and seat installed and fenders built and shocks installed, and was about to take it out for a road test and discovered antifreeze pouring out from underneath, Thought, well just a hose leaking, no big deal, But NO WAY, I discovered the block was cracked, about 6 inches long, on the drivers side just about 3 inches below the freeze plugs, It has had antifreeze in it and has not been ran so I know it didnt run hot, So cant figure out why it cracked, Well guess its time to start looking for the V-8 to install now...
too bad you're not closer to me...I have brand new amc crated blocks and I'm pretty sure they were for '76 years.

g'luck!
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post #10 of 17 Old 03-08-2013, 05:59 AM Thread Starter
semperfi1919
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Quote:
Originally Posted by JrTjK View Post
too bad you're not closer to me...I have brand new amc crated blocks and I'm pretty sure they were for '76 years.

g'luck!
I dont think I would rebuild another 258 to go into it if the JB weld didnt work, I am going to go with a V-8 after this one.

MSG Cooley Sean, KIA Feb 3 2005
1LT Oneto-sikorski,Robert KIA Oct 31 2005
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post #11 of 17 Old 03-08-2013, 06:09 AM
timgr
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Quote:
Originally Posted by semperfi1919 View Post
I dont think I would rebuild another 258 to go into it if the JB weld didnt work, I am going to go with a V-8 after this one.
AMC 4.0L, with Mopar MPI. Easier swap than a V8, drops right in, plenty of power, and better mileage than the 258. And they are plentiful.

1) '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps. 2) '82 J20 360/T18/NP208/3.73, KOs, 7600 GVWR 3) '75 CJ-6, 304/T15, PS, BFG KM2s, soft top 4) '95 VW Golf Sport 2000cc 2D
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post #12 of 17 Old 03-08-2013, 06:25 AM
Matt1981CJ7
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An AMC V8 is a simple swap, as well, assuming your tranny is compatible. One motor mount is different, but otherwise it's pretty much plug and play with the 258 harness.

Matt
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post #13 of 17 Old 03-08-2013, 06:45 AM
timgr
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The AMC V8s are great engines - I own both a 304 CJ and a 360 J20. Both will be going TBI when I get the time to pursue the upgrade. And converting a 258 Jeep to an AMC V8 is easy, compared to all other options except maybe the AMC 4.0L.

However, to me, the 4.0L makes more sense here, considering the price of gasoline. And the 4.0L comes with the excellent Mopar MPI. 4.0L donor cars are a lot more plentiful than any AMC V8 donor. An the 4.0L has as much power on the highway as a 360 in factory trim. Lots of compelling reasons to go with the 4.0L rather any AMC V8.

A modern SBC swap could approach the same mileage as the 4.0L, and have more power, but that's a whole other cost/complexity universe.

1) '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps. 2) '82 J20 360/T18/NP208/3.73, KOs, 7600 GVWR 3) '75 CJ-6, 304/T15, PS, BFG KM2s, soft top 4) '95 VW Golf Sport 2000cc 2D
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post #14 of 17 Old 03-08-2013, 07:02 AM
Matt1981CJ7
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Quote:
Originally Posted by timgr View Post
An the 4.0L has as much power on the highway as a 360 in factory trim. .
That's a little mis-leading. It's quite easy to get over 300 hp with a 360, using mostly stock components. I think you'd be lucky to get 200 hp from a 4.0L.

I don't see where the OP mentioned gas mileage as the primary factor. In fact, I believe he specifically expressed a desire for a V8.

If that's what he wants, an AMC V8 will be the easiest swap.

Matt
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post #15 of 17 Old 03-08-2013, 08:46 AM
travisrda
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put a 401 in it? That way you won't be putting a cheby in it and you will keep it amc. and it is a pretty easy swap.
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