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Thread: 4.0L Cracked Head - Welding Fix?

  1. #1
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    Default 4.0L Cracked Head - Welding Fix?

    My 2000 TJ (100k miles) has been in the shop for a week getting the head gasket fixed. Yesterday they called with ONE more problem. The machine shop that was doing the milling found a crack. I didn't get a ton of info on the location and severity, but they suggested that I have the machine shop go ahead and weld the crack and complete the job.
    SO, is this my best option for a cost effective solution? I don't want to spend a fortune (as the shop suggested a new head was going to be expensive), but I do was the job done right. I also don't want to run into any additional problems down the road.
    Thank you in advance for your input and opinion-
    Craig

  2. #2

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    will they warrant the weld?

  3. #3
    Master Tech williambmac's Avatar
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    Depends on how bad the head is cracked and if the machine shop is going to weld it the correct way.
    The correct way is called furnace welding. the head or block is heated in a furnace the approx 1300 degrees and rod is fed into the crack. the cylinder head is then wrapped in a blanket and allowed to cool, it takes several days. then you get to remachine the head and re-assemble.
    It is a little time consuming but the correct way to do it.
    You can also purchase a brand new cylinder head assembly from https://www.alabamacylinderhead.com/productlist.php
    2005 Rubi LJ 35's 5.5 Clayton
    lots of extras

    2000 wrangler 35" Goodyears Rock-trac super 88 hp30 4.88Terminator trans 5.5" RE/Clayton lots of xtras. RIP
    2000 WJ 4.0 addco upcountry springs bilsteins
    2001 H-D Duece Black and Chrome (For Sale)
    1997 YZF1000 200mph Superbike (RIP)

  4. #4
    Registered Chris142's Avatar
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    there is a known problem with the 2000 ans 2001 heads with them cracking. I wouldn't mess with fixing one. I'd buy that one williambmac linked you to and be done with it.



  5. #5
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    Quote Originally Posted by williambmac View Post
    Depends on how bad the head is cracked and if the machine shop is going to weld it the correct way.
    The correct way is called furnace welding. the head or block is heated in a furnace the approx 1300 degrees and rod is fed into the crack. the cylinder head is then wrapped in a blanket and allowed to cool, it takes several days. then you get to remachine the head and re-assemble.
    It is a little time consuming but the correct way to do it.
    You can also purchase a brand new cylinder head assembly from https://www.alabamacylinderhead.com/productlist.php
    It is my understanding that the process explained above is how the shop will fix the crack, so that is good. Also, in speaking with the shop; welding was suggested over purchasing new from the machine shop (and from speaking with others, they are "the best is KC)". SO, I guess I have to "trust" that it will be completed correctly.
    I don't know... maybe I have a hard time trusting something that I know so little about. I am the kinda of person that likes to know what I am getting myself into.
    Thanks for your input guys!
    Craig

  6. #6
    Master Tech williambmac's Avatar
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    If that is how the shop is going to be repairing your cylinder head, I would not hesitate trusting the repair. I have had numerous repairs done in that fashion and never had an issue, most are on high horsepower race engines.
    That being said....the 0331 cylinder head is prone to cracking. You may be better off replacing it with the brand new casting from alabama cylinder head. You should ask the machine shop how much the welding repair and the machining of the head is going to cost including the valve job. Then weigh out the cost difference between remanufacturing your head or replacing it.

    You may want to check out this post.
    http://www.jeepsunlimited.com/forums...heads+cracking
    Last edited by williambmac; 03-05-2010 at 03:42 PM. Reason: edit
    2005 Rubi LJ 35's 5.5 Clayton
    lots of extras

    2000 wrangler 35" Goodyears Rock-trac super 88 hp30 4.88Terminator trans 5.5" RE/Clayton lots of xtras. RIP
    2000 WJ 4.0 addco upcountry springs bilsteins
    2001 H-D Duece Black and Chrome (For Sale)
    1997 YZF1000 200mph Superbike (RIP)

  7. #7

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    Quote Originally Posted by williambmac View Post
    If that is how the shop is going to be repairing your cylinder head, I would not hesitate trusting the repair. I have had numerous repairs done in that fashion and never had an issue, most are on high horsepower race engines.
    That being said....the 0331 cylinder head is prone to cracking. You may be better off replacing it with the brand new casting from alabama cylinder head. You should ask the machine shop how much the welding repair and the machining of the head is going to cost including the valve job. Then weigh out the cost difference between remanufacturing your head or replacing it.

    You may want to check out this post.
    http://www.jeepsunlimited.com/forums...heads+cracking
    x2. The 0331 head is known to crack. I wouldn't waste your money fixing it only to have the possibility of it cracking again later down the road. I put an Alabama Cylinder head on my 2000 XJ and have had good results so far.

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