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post #1 of (permalink) Old 08-21-2000, 07:33 PM
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Cracked Block?

I recently acquired an 80 model CJ-5 for a steal--$1200.00. Body is in perfect condition--ready to be painted, the tranny, case, and diffs seem to be in good shape-60,000 miles. The guy I bought it from lived way out in the middle of nowhere and was willing to sell it cheap if I would come get it--the only problem with the vehicle he said was it had a "cracked block." This may sound ignorant, but what the heck does that mean--I searched all over the outside of the block-can't find any cracks. So I started tearing into the engine--oil in the carb, and air cleaner. Bad valve cover seal--the valves seem to be in working order..... Anyway, am I missing something here???? What does cracked block mean? Can it be internal? HELP!!! It has the silly 151 GM in it, that will soon be swapped, but it would be great to have it running to buzz around in until the time and money acrue to do the swap.

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post #2 of (permalink) Old 08-21-2000, 08:00 PM
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Re: Cracked Block?

My guess would be that the ole feller was finding antifreeze in the oil or vise versa,yes its most likely internal,possibly waterjacket, or often a cracked head or even a faulty head gasket is mistaken for a cracked block,usually from overheating,or freezing without antifreeze.if it runs well,and dosnt show any outward signs of a crack,and your gonna swap it out anyway,I would just top all fluids to exactly full,and watch them real close for "disapearing" or for change of color.

post #3 of (permalink) Old 08-21-2000, 08:07 PM
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Re: Cracked Block?

"Cracked Block" is one of those generic terms used by people that don't have a clue what's wrong.

Let the Jeep sit overnight, Get your self a glass jar, and put it under the drain plug.
Crack the drain plug, and back it out about three turns, just shy of coming out.
See if water collects in the jar.

If no water in the jar, no cracked block inside.

If you do get water, could be anything from someone leaving the hood open to running through high water, to leaking head gaskets or intake manifold.

If the jeep has sat a long time with out starting, do all the regular stuff, change the oil and filter, the air cleaner, the gas in the tank, check the trans and diffs.
Pull the plugs and clean/ regap them.
Give the cylinders a LITTLE shot of oil while you have the plugs out.
Check the rotor nose and cap terminals....

Fill up the radiator, and fire the engine.
Use ether to get the engine to fire. Squirt a little oil down the intake before using ether doesn't hurt anything.
The quicker the engine fires, the better off you are.

Don't rev up the engine at first more than it takes to keep it running.

After it's run long enough to get up to operating temperature, (feel the upper radiator hose to make sure the thermostat is working, don't trust a gauge until you do, leave the radiator cap loose, and keep the radiator topped off) shut it down and let it set one day, and test the oil like I explained before.

Check the water, if the block is really cracked, the water will escape, and the radiator will be low.

If you don't find water in the oil, or oil in the water, the block is not cracked inside.
If you don't loose water, and you don't find where it's been running down the side of the block, the outside of the block isn't cracked.

"I Have The Body Of A God... Buddha"
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post #4 of (permalink) Old 08-21-2000, 08:22 PM
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Re: Cracked Block?

Thanks for the suggestions guys. i haven't even tried to crank it yet. We'll see.....

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