Cracked block - JeepForum.com
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post #1 of 108 Old 04-08-2019, 07:55 PM Thread Starter
Robbiescd
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Cracked block

With a very heavy heart, I’m sad to say that my less than 1 year old engine has a crack in it.
I’ll
This morning I decided to take the Jeep to work. About 7 miles into the drive, I smelled coolant. I looked at my temp gauge and it was pegged out. I immediately stopped and had it towed back home. This evening, I went to take a look at it and evidently I had developed a serious coolant leak on the hose at the bottom of the radiator. This of course caused the motor to overheat and form a crack right behind the water pump on the block.

I’m embarrassed and extremely angry! This is a rebuilt motor that I have had in the Jeep for less than a year! I barley have 500 miles in it!

It’s the 4.2 with the injection conversion on it. I’ve read about these block sealers. Are these any good?

Any other suggestions? Just shelled out $3k last year. Can’t shell out another for another engine swap.

Easy on the “dumb a**” comments! I’ve already beat myself up pretty badly! I always check my gauges, but traffic was a little heavy and didn’t look down!

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post #2 of 108 Old 04-08-2019, 08:55 PM
Jeepsr4me
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how do you know its a crack..?
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post #3 of 108 Old 04-08-2019, 09:21 PM Thread Starter
Robbiescd
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I believe I see the crack. I filled up radiator, cranked engine and saw, what I thought to be, fluid leaking out of a pin hole sized area. It looks like a crack that leads to the pin hole....I suppose the crack could be some sort of casting marks.

But the more I’m reading, I’m seeing that it’s awefully hard to crack a block. Normally the head will crack first. When I let it run, I see coolant dripping alongside the oil pan. If I follow the “stream”, it looks like it originates just behind the water pump on the drivers side....right below the exhaust manifold.
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post #4 of 108 Old 04-08-2019, 09:25 PM Thread Starter
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Another observation....when I saw the high temp, I shut her down. Steam was coming from motor. It looked like steam coming from right behind the water pump. I assumed it was the water pump seal. But now, I’m not so sure.
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post #5 of 108 Old 04-08-2019, 10:42 PM
Chrisnvegas
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Before you go any further, tear it down and see what's up. Remove the radiator and water pump. Clean and inspect.

Or, get some dye. De-grease the engine. Add the dye and using a black light in a darkish garage, the source of the leak will literally jump right out at you. Yeah, it takes a lot to crack a cast iron engine block unless it's freeze damage.
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post #6 of 108 Old 04-09-2019, 05:18 AM Thread Starter
Robbiescd
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Nothing much to degrease! Have hardly any miles on it. I’ll probably pick up some dye and give that a shot.
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post #7 of 108 Old 04-09-2019, 06:56 AM Thread Starter
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So the more I read, I’m seeing statement like, “in all my years, I’ve never seen a cracked block”. Am I being to optimistic that what I think I’m seeing could possibly not be a pin hole leak? Maybe air flow around engine is making it seem like it’s a pinhole? I’ll try and take a few photos this evening and post.
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post #8 of 108 Old 04-09-2019, 09:16 AM
bpounds
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Don't get too worked up until you have pulled the water pump and t-stat housing. Chances are fair it has just blown a gasket. Unfortunately there are thin webs of cast iron around the water pump opening that could easily crack. On the other hand, might be an easy area to weld up too. You're not going to know until you disassemble some stuff.


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post #9 of 108 Old 04-09-2019, 09:49 AM Thread Starter
Robbiescd
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Thanks so much for the replies. Do you suggest possibly putting dye in the radiator to see where the leak is or just start dismantling.
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post #10 of 108 Old 04-09-2019, 10:56 AM
Jeepsr4me
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I would not waste money on dye. clean the area you think is leaking and dry it real good.
Now go to a parts store and rent for free the coolant pressure tester.
Put up to 18psi in the system and see if you can see it leaking.
Normally the fan wind blow the coolant every where so you really dont know where its leaking..
Seen T stat and water pump gaskets leak... and you think its the block..
Also when the engine was built did they use the sealant on the front head bolt? It goes thru the water passage.. SO if you got pudding for oil it may be that or a head gasket bad..
I would bet on the Tstat or hoses or pump...
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post #11 of 108 Old 04-09-2019, 11:06 AM
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Yeah, dye is good when you have a small leak and you're not sure where it is running down from. Usually oil leaks, sometimes you don't even know what kind of oil it is.

Pressure testing is good, but first you've got to get all the air out of the system. You can't see where air is leaking from, so you have to get the air out of the system before pressure testing. It's a good idea, but I think at the point where you are now, I would just pull that water pump and look. It's a 30 minute job to strip the front end of the block and head.

Bill
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post #12 of 108 Old 04-09-2019, 11:06 AM Thread Starter
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I thought about the pressure test and trying that. The coolant is actually dripping from the oil pan....running down the block and settling on the rim of the oil pan. I’m going to keep my fingers crossed.

There were a ton of folks on this site giving me advice when I was doing the build. Haven’t been steered wrong so far! So I hope everyone is right.....blown gasket in pump or thermostat.
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post #13 of 108 Old 04-09-2019, 11:08 AM
bpounds
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A coolant system pressure test kit is less than $50 from Amazon. I kind of think everyone should have one. I have the Miti-vac set. If you don't use it to find your leak, you should use it after you're all buttoned back up. That might have saved you from being where you are now.

Bill
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post #14 of 108 Old 04-09-2019, 11:11 AM
rocketboy
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If you do have a crack (hopefully you don't!), don't entertain attempting the "JB Weld" fix. It doesn't work. I speak from experience. Learn from my stupidity...

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post #15 of 108 Old 04-09-2019, 01:04 PM Thread Starter
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I’m not planning on the JB weld. It did cross my mind to use some sort of “filler” product. I think K Seal and some other products “claim” to stop cracks in the block. But I’m going to take it one step at a time.

I assumed the worse, but after some of the comments and those I’ve read on other posts, I’m going to keep my fingers crossed!
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