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  1. #1

    Default How widespread is the Castech head crack?

    I just wonder how big of a problem this has been since there must be 10's of thousands of these motors out there.
    I guess I am just concerned since I just bought one with the 706 casting.
    Should I nip it in the bud and go ahead and replace the heads now?
    I do have another question that may be easier to answer/talk about.
    Are all the 706 heads made by Castech? Or is that why you have to look inside to see the Castech marking?
    I know I have the 706 cause I can see it clearly on the outside of the head passenger side.

  2. #2


    I found this about identifying the Castech heads. It does not indicate the 706 marking in the document. I have been searching for a few days and it seem as if no one has the answer to the question about only castech making the 706 head. I did locate some pictures that showed different font for the 706 number, but those posters never indicated if they found the castech logo inside.Sorry I can't help more.
    Last edited by Pikey; 01-03-2012 at 01:25 PM.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  3. #3


    Thank you for the reply, I think I found the same thing you did. Seems like you must look inside to properly identify.
    The good news for now I guess is that I'm not loosing coolant. So nothing urgent at this time.

  4. #4


    i don't know if mine falls into this category...i have the 6.0 motor and just recently found a hairline crack on the passenger side head and was losing coolant...good thing it was under warranty...only cost me $ it could've been worse.
    Mike - SoCal

    07 Sierra 1500HD
    Ultra Mammoth Wheels 17x8
    Nitto Terra Grapplers - 305/70/17
    Line-X Bedliner and Wheel Wells
    NFab Nerf bars
    CST 4" Spindle lift

    08 Hybrid Tahoe - wifey's ride
    McGaughy's 2/3 drop kit
    22x9.5 Tyfun Wheels
    Nexen Roadians 285/45/22

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