HELP! 4.0L overheated, cracked block, now I need a new motor. - Page 2 - JeepForum.com
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Go Back JeepForum.com > Models > Jeep Wrangler Forums > TJ Wrangler Technical Forum > HELP! 4.0L overheated, cracked block, now I need a new motor.

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Unread 09-19-2012, 10:57 AM   #16
LiveAndLearn
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for 5800 you could put a corvette motor in it....

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Unread 09-19-2012, 11:00 AM   #17
TEXAS_TJ
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Quote:
Originally Posted by 3eff_Jeff View Post
I'm with 98tjsport. The 4.0 is super strong block. It's not a diesel block, but it's still way overbuilt. Firestone is trying to fleece you ($5800 with no upgrades sounds like robbery to me).

What does your oil look like? Does it look like dark to black cooking oil or a milkshake? Pull your oil fill cap on the top of the engine and run your finger around the inside. Any frothy residue? (These symptoms would mean the coolant was leaking into the oil.)

Are you getting white smoke out of your tailpipe? You should see something coming out of your tailpipe if the block is cracked and the coolant is leaking into a cylinder.

Is there any coolant in the engine bay? It should be an orange liquid (green if someone put the wrong, older stuff in), and it probably dries to a white powder or otherwise looks like a white hard-water stain when dry. Any of that in the engine bay? If there is, can you trace where it's leaking from?

Have you checked your radiator cap? When you pull it off, there's a rubber gasket in the cap that should be smooth and clean. If the rubber is cracked at all, toss it and get a new one. It should be an 18psi cap, and they're cheap (Summit has them for $5).

Also, all of these symptoms can be caused by other things failing, like the head gasket, which everyone keeps bringing up for a reason. You've got a 2004, so you should have an 0331/TUPY head, which is unlikely to crack (but would likely go before the engine).

Again, take it to someone else. Firestone's estimate is bad, and I would be surprised if they didn't misdiagnose your problem. The block is the last thing to check. At 80,000 miles, your 4.0 is just getting broken in.
Ok, thanks for the input. I forgot to mention that I also replaced the radiator cap when I replaced everything else, so it should be good. My out-of-town guests just left last night, so I'll go pickup the jeep tonight and check the oil to see what it looks like. I assume I can fill the radiator and drive it about 4 miles home and it'd be ok as long as it doesn't over-heat, right? I'll have my Wife follow and look for any smoke out of the exhaust as well.

If it is the head gasket and not the block (as everyone is suspecting) is this something that needs replaced asap and can cause more damgage or could I just replace the radiator and keep driving it?
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Unread 09-19-2012, 11:01 AM   #18
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Originally Posted by LiveAndLearn View Post
for 5800 you could put a corvette motor in it....
I actually own a 2001 Corvette also.
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Unread 09-19-2012, 11:26 AM   #19
3eff_Jeff
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Quote:
Originally Posted by TEXAS_TJ View Post
Ok, thanks for the input. I forgot to mention that I also replaced the radiator cap when I replaced everything else, so it should be good. My out-of-town guests just left last night, so I'll go pickup the jeep tonight and check the oil to see what it looks like. I assume I can fill the radiator and drive it about 4 miles home and it'd be ok as long as it doesn't over-heat, right? I'll have my Wife follow and look for any smoke out of the exhaust as well.

If it is the head gasket and not the block (as everyone is suspecting) is this something that needs replaced asap and can cause more damgage or could I just replace the radiator and keep driving it?
It's something you want to get fixed sooner rather than later. Particularly if you are losing coolant as fast as you are. (Which also means: that coolant has to be going somewhere, and if you can figure out where, it will tell you a lot about what the problem is.) The head gasket is also a lot easier to fix than replacing the whole engine. I won the 0331 head crack lottery with mine, and I did the work myself. It's a lot less work than replacing the engine, and should be much cheaper to have done, but it's still a non-trivially repair, even for the mechanically inclined.

Before you top it up and turn it on, check the oil. If it is milkshake consistency and has a coffee with cream color, you don't want to drive it or turn it on (except maybe to check for smoke out the exhaust, and that might still be a bad idea). When there's enough coolant in it to make it milkshake consistency, it doesn't work as an engine lubricant and the chemicals in the coolant will eat away at your bearings. (So the answer is: yes, this can cause more damage if left alone.)

But, as many people (including myself) who are saying "head gasket", we don't know where the leak is yet...
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Unread 09-19-2012, 11:33 AM   #20
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Originally Posted by 3eff_Jeff View Post
It's something you want to get fixed sooner rather than later. Particularly if you are losing coolant as fast as you are. (Which also means: that coolant has to be going somewhere, and if you can figure out where, it will tell you a lot about what the problem is.) The head gasket is also a lot easier to fix than replacing the whole engine. I won the 0331 head crack lottery with mine, and I did the work myself. It's a lot less work than replacing the engine, and should be much cheaper to have done, but it's still a non-trivially repair, even for the mechanically inclined.

Before you top it up and turn it on, check the oil. If it is milkshake consistency and has a coffee with cream color, you don't want to drive it or turn it on (except maybe to check for smoke out the exhaust, and that might still be a bad idea). When there's enough coolant in it to make it milkshake consistency, it doesn't work as an engine lubricant and the chemicals in the coolant will eat away at your bearings. (So the answer is: yes, this can cause more damage if left alone.)

But, as many people (including myself) who are saying "head gasket", we don't know where the leak is yet...
Ok, I'll check the oil first.
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Unread 09-19-2012, 12:26 PM   #21
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Wait...the first question I have is the Jeep still running? Have you tried it, even if just starting it for a moment to search for any leaks?
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Unread 09-19-2012, 12:36 PM   #22
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Originally Posted by Mboelts View Post
Wait...the first question I have is the Jeep still running? Have you tried it, even if just starting it for a moment to search for any leaks?
Yes, the Jeep still runs. I just have to fill the radiator with water first and take along spare gallons. Seems to make it 3-5 miles before it starts getting hot due to the radiator leak.
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Unread 09-19-2012, 01:56 PM   #23
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I just don't see how you block cracked overheating once. If you drove it all day I would say yea but, just a few minutes I don't see how. My watermpump went out and I drove it at 260 for almost 10 miles to get it home. All it did was compromise the thermostant and I went ahead and changed my fan clutch while I was at it. Changed my oil just to be safe and it looked really good. Jeep runs like new. 5,800 is alot of money to replace that engine when you can buy a drop in stroker from Chad Golen for 4,200 to 4,500 depending upon your year 4.0L. Like others said get it away from Firestone those lube monkeys don't know anything. I don't think they are even ASE lol.
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Unread 09-19-2012, 01:59 PM   #24
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At most you would have done was blow a head gasket being its iron on iron setup not saying it can't but, the chances are really slim.
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Unread 09-19-2012, 02:08 PM   #25
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If it is running, not missing, or chugging or anything like that...engine is not the issue. I would get it out of there, fix the overheating issues by putting in a stock rad, stock pump, thermo, and stock cap on it. Then run it and see what happens. I would NOT take the advice of some place that just randomly says the engine is bad with no proof. Especially not one of the 4.0 blocks
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Unread 09-19-2012, 02:08 PM   #26
Speed94
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I just replaced my block with new water pump, hoses, thermostat, head, for under 3k including labor and warranty...
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Unread 09-19-2012, 05:12 PM   #27
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If it checks out that they were indeed lying to you I would go as far as filing a complaint with the local BBB. You might save a neighbor a lot of money down the road.
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Unread 09-19-2012, 05:25 PM   #28
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Firestone...........now thats the ticket!

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Unread 09-19-2012, 06:58 PM   #29
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Contrary to the opinion expressed earlier, the "block test" is a tester that uses a special fluid that changes color in the presence of combustion gases. You fill the tester with the fluid, remove the radiator cap, and place the tester in the radiator opening with the engine running. If there are combustion gases in the coolant, the special fluid will change color. Typically one of a few things will allow combustion gases to get into the coolant - a bad head gasket, a cracked head (cracked from the combustion chamber into a cooling pocket in the head) or a cracked block (typically a crack in the cylinder wall that passes through into a water jacket). This may be why they said you have a cracked block, which is possible, but not as likely as the other two scenarios. Note: the earlier poster was describing what is commonly called a "cooling system pressure test".

Even if it is just a head gasket, you should have the head checked for flatness. Yes, it's cast iron, but it's an awfully long piece of cast iron - inline 6 (or more) cylinder engines have always been more prone to warping a head if overheated due to the length of the casting. The shorter casting of a V6 or V8 engine is less prone to warping since it is compact and therefore more resistant to twisting.

Bottom line, pull the head and find out what is going on. Be aware that crack in the cylinder wall can often be so subtle that it's difficult to see.
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Unread 09-19-2012, 06:59 PM   #30
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Firestone is the worst place to take your ride. They will lie and rape you with a smile on their face. Never heard of a block test. Sounds like something they made up. Run as fast as you can from them.
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