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Thread: Duramax Head Gasket Replacement

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  1. #1
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    Wink Duramax Head Gasket Replacement

    Well, I'm into it. Pulled the truck into the cleaned-out garage yesterday, and began the dis-assembly. A lot of prep work had to be done before hand...

    Had originally planned to let a Duramax enthusiast (GM mechanic) I've known since about 2007 do the work, but it didn't work out. As complex a project as this is, and being hard to please, it's best if I do it anyway - for a variety of reasons (some shocking and some, well, just because). More later...

    Onward and upward!

  2. #2
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    Anxiously await lottssa pics
    (1) 1995 Suburban 2500 4x4
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  3. #3
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    Watching as well i think the same job is in my future on my 2001 Tow truck.
    Getting a hard rad hose,and losing fluid,smoke on starts
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

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    Will there be Pop Corn provided?
    "The Constitution is not an instrument for the government to restrain the people, it is an instrument for the people to restrain the government."
    -Patrick Henry


    A5150nut
    2006 K3500 D/A
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  5. #5
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    BYOPC....
    Shop towels advised.....Coveralls mandatory dress code.....yeah buddy
    (1) 1995 Suburban 2500 4x4
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  6. #6
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    I'm looking at 2 possibilities, as of right now, for why I was seeing excessive pressure in the cooling system. By the way... there are patches of soot visible inside the coolant surge tank, which is a dead give-away.

    The 2 possibilities...

    #1- The No. 2 injector failed at about 120,000 miles (I identified it as having a way out of range fuel rate), which produced a "chugging" while the engine idled, like at a stoplight. I suspect that may have stressed the head gasket surrounding that cylinder - maybe.

    #2- The excessive pressure in the cooling system was identified not long after an injector replacement (see #1). My GM Duramax mechanic/enthusiast friend seems to think the problem will be identified as a cup seal leak. He's seen enough LB7 cup seal leaks in his day (that follow an injector replacement) that he developed his own procedure to prevent them from happening. If my truck's problem is due to a cup seal... then it may have been a byproduct of risky/lazy injector replacement (meaning it was an independent shop's fault... ). Unfortunately, without taking it apart there's no way to tell if the excessive pressure is due to a bad gasket or a cup seal leak.

    Another "by the way".... according to my mechanic buddy, the design of the Duramax head gasket produces a more likely problem at the #2 and #7 cylinder. If the head gasket were to fail... and that's not injector or cup related, the problem always winds up being associated with #2 or #7.

    Have a look near the end of the following story on water pump replacement to learn more about head gasket failures*.... (LB7 cup seal problems). https://www.thedieselpage.com/durama...xwaterpump.htm

  7. #7
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    Dig into it Jim
    Gonna be interesting to see what ya find...
    (1) 1995 Suburban 2500 4x4
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  8. #8
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    Here's a shot of the engine bay as it exists this morning (June 2, 2021). Getting closer... I need to unbolt the exhaust up-pipe from the exhaust manifold and remove the steel fuel lines. There's still a fair amount of electrical and plumbing to get the left side clear enough to look like this side.

    I know there's a grounding strap on the back of the driver's side head (left side) that'll need to be unbolted. And, I think I just need to remove the three bolts at the bottom of each exhaust up-pipe to then free the heads... If I'm missing something, let me know. The book says the turbo needs to be removed to do a head R&R, but it looks like I can get the intake Y-pipe unbolted without removing the turbo. Just need to remove the turbo compressor inlet elbow to allow access to the intake bolts... I think.

    Getting the electrical connectors disconnected up to this point took quite some time... There are many different types used here, and each has its own enigmatic snap-lock design (plus needing to be very careful due to 20 year old hardened/fragile plastic). You can see the soot in the plastic coolant surge tank...

    Last edited by More Power; 08-24-2021 at 09:02.

  9. #9
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    We've done them in chassis I believe one time. Then started removing engine from chassis altogether. Easier to work on this way. Most lift the cab, and we always thought about it, but the risk of doing any paint and body damage...

    Use a 10 mm ujoint socket for the turbo inlet bolts. The ones that I have are Snap on and have a very shallow socket.

    ANY signs of rust on the injector inlet bowls or supply lines I would replace with new, in fact a set of SAC 00 injectors with new lines would be mandatory on my list. Hazing at idle shortly down the road will tend to break your spirit and all LB7 VCO seem sto do this. Some sooner than others.
    Kennedy Diesel-owner
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  10. #10
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    Quote Originally Posted by Kennedy View Post
    We've done them in chassis I believe one time. Then started removing engine from chassis altogether. Easier to work on this way. Most lift the cab, and we always thought about it, but the risk of doing any paint and body damage...

    Use a 10 mm ujoint socket for the turbo inlet bolts. The ones that I have are Snap on and have a very shallow socket.

    ANY signs of rust on the injector inlet bowls or supply lines I would replace with new, in fact a set of SAC 00 injectors with new lines would be mandatory on my list. Hazing at idle shortly down the road will tend to break your spirit and all LB7 VCO seem sto do this. Some sooner than others.
    Thanks John.

    The injectors in the engine now only have about 20k on them. I had planned on having them cleaned/checked/tested before they went back in. But, I hear you on the "spirit" point... It's a lot of work to complete a project like this, to then have an injector issue soon/right after... I'll think about it...

    Do you agree that the bottom 3 bolts on the exhaust up-pipes will free the heads from the exhaust system? Or, are there any bolts on the back side of the heads that secure the heat shields?

    The GM mechanic I mentioned earlier told me that they lift the cabs too, but I was against it for of a variety of reasons - including damage to the cab, and then having persistent gremlins move in (with electrical, A/C, brakes, Allison shift cable, steering shaft, etc.). He then said his next option would be to pull the engine. Working mostly alone and without a vehicle lift, I pulled each inner fender wheelhouse and front tire/wheels, then lowered the front of the truck about 5-6 inches onto jackstands. Using plywood, I then made a 6" high x 24" wide x 48" long platform to stand on while leaning over the rad area. I can still pull the engine if it comes to that.
    Last edited by More Power; 06-03-2021 at 08:54.

  11. #11
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    I am with John

    I would clear off the crap on top and then yank the engine out.

    One little issue in a hard to reach spot can lead to a redo.....and that stuff sucks.

    Take your time and yanking the engine will not be all that bad.

    THEN... you can walk up and get quite intimate with the old girl....
    And if there are any other things that show up....they can be dealt with easily.

    PLUS....While the engine is out...you can muck out the engine bay and make it all spiffy.....
    (1) 1995 Suburban 2500 4x4
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  12. #12
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    Had to buy a few more tools... i.e. a short 1/2" drive 12mm 12-point socket, a 10" long 12mm 12-point box wrench (need the leverage), 19mm flare nut wrench for the steel injector hard lines (although I used a 3/4" crow's foot, which worked perfectly), a set of 1/4", 3/8" and 1/2" drive adapters for my battery powered drill/driver, a set of metric Allen ball drivers and a couple misc tools to help out. Then, I removed the passenger side exhaust manifold and glow plugs. Up next is the driver's side exhaust manifold/glow plugs. I've heard that it's easier for one person to get a head up and out of the engine bay if the exhaust manifold has been removed. Gotta be careful not to ding the aluminum deck surface of the head.

    Advice from John and others I trust say the ARP studs are the better choice over the factory TTY head bolts. So... we'll go with that. More later...
    Last edited by More Power; 08-24-2021 at 09:07.

  13. #13
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    Hang in there Jim......It will get easier the more stuff ya get off of the beast.....
    (1) 1995 Suburban 2500 4x4
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  14. #14
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    Thumbs up Good show for the DuraMax members.

    This will give you a real workout, Jim. If I were closer to Montana I would be there to help you. If you do pull the engine out, you can do everything necessary to have it run another 20 years, and by then you might be ready for something different, like the diesel El Camino you have always wanted.
    Dr. Lee

    1984 C-10, custom 6.5L SAA, custom 700R4, Gone but NOT FORGOTTEN

  15. #15
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    The head and gasket look to be unremarkable. Really good for a 20 year old, actually. Just an observation.

    80/120 grit on an aluminum head? I can see Scotch-Brite or 600 as reasonable, and what I might use. Anyone who'd suggest 80 grit gets no more of my attention. I doubt you could fix that with a mill.
    1985 Blazer 6.2
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  16. #16
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    When re-doing the heads on a 6 liter gasser (aluminum heads) the FSM wants the surface to be "R15". When I got them back from the machine shop, you could almost see your face in the surface. In other words, check the FSM for surface requirements. Just a thought.

    Bill
    91 Buick Roadmaster/Avant 6.2 NA conversion (gone but not forgotten)
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  17. #17
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    According to (the latest bulletin regarding head/gasket prep and install):

    Bulletin No.: 06-06-01-006C


    Date: October 30, 2009


    Subject: Information on 6.6L LBZ, LB7, LLY Duramax(R) Diesel Engine Cylinder Head Gasket Design Change - New Head Gasket Part Numbers and Head Bolt Torque Specifications


    Models:
    2001-2006 Chevrolet Silverado
    2003-2006 Chevrolet Kodiak C4500/5500 Series
    2006 Chevrolet Express
    2001-2006 GMC Sierra
    2003-2006 GMC TopKick C4500/5500 Series
    2006 GMC Savana
    with 6.6L Duramax(R) Diesel Engine (VINs D, 1, 2 - RPOs LBZ, LB7, LLY)

    [snip]

    Special Cleaning Requirements
    For 2001-2006 vehicles produced with the first generation head gasket, special attention must be given to the cleaning of the engine block and cylinder head surfaces when servicing with a second generation gasket. The crimped areas (1) on the first generation gasket may, over time, allow corrosion buildup where they contact the block and cylinder head surfaces. The second generation gasket has raised ribs that seal at these crimped areas (1). A special cleaning procedure is required to ensure proper sealing.


    Cleaning Procedure
    1. Remove the old head gasket using service manual procedures. Save the gasket for reference until the repair is completed.
    2. Place clean rags in the cylinder bores and pushrod openings in order to keep out debris.
    3. Use the J-28410 or equivalent to carefully clean the gasket sealing surface of large sealing or corrosion matter. When scraping, take care not to scratch or gouge the metal surfaces. Do not push the debris into oil, coolant, and combustion openings or bolt holes.
    4. Inspect the gasket sealing surfaces for corrosion, especially in the areas that were in contact with the crimped tabs of the first generation head gasket. If corrosion is present, continue with the rest of the steps in this procedure for proper cleaning. If the sealing surface is sufficiently clean and smooth, use the revised torque specification listed towards the end of this bulletin and continue with published service manual procedures to complete the repair.
    5. For surfaces that have corrosion or pitting, wrap a piece of flat steel (4"x 2" or larger) with 600 grit wet grade sand paper. Using Moisture Displacing Lubricant, P/N 88862629 (in Canada, use 89020803) or equivalent, wet sand the block surface to remove any remaining gasket material or corrosion. Do not use any paper coarser than 600 grit.
    Notice
    - Do not use any power type sanding devices.
    - Do not use a wire brush or wheel to clean gasket surfaces.
    - Do not use chemical cleaning agents on gasket surfaces.
    6. Take care to keep the sanding block parallel to the block surface and evenly sand the sealing surface. Some areas of corrosion will still show a stain. Do not attempt to wet sand these areas down to a shiny metal surface.
    7. Change the sanding paper when it becomes clogged. Carefully and frequently wipe the surface, using a clean cloth each time, to prevent sanding debris from building up and contaminating the oil and coolant cavities.
    8. Clean the bolt threads and holes and remove the rags from the bore cavities and pushrod openings.
    9. Repeat the above cleaning procedure on the cylinder head gasket surface.
    10. Clean the engine block and cylinder head gasket surfaces with Brake Parts Cleaner, P/N 88862650 (in Canada, use 88901247) or equivalent, to remove any traces of oil or debris.
    11. Using the revised head bolt torque specification below, reassemble the engine with NEW M12 cylinder head bolts according to service manual procedures.


    Also:

    Bulletin No.: 07-06-01-009A
    Date: November 02, 2009

    Addresses head gasket thickness identification, Gen 1 crimped gaskets vs. Gen 2 riveted gaskets, and revised head bolt torque and angle procedure. DO NOT use the original Gen 1 head bolt torque procedure with Gen 2 riveted gaskets. Definitely worth a read.

    RTFM (note to self)
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  18. #18
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    I can't imagine using 80 grit.....omg...
    (1) 1995 Suburban 2500 4x4
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  19. #19
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    Quote Originally Posted by More Power View Post
    Thanks Greg... does the info you have list the new torque specs - i.e. "Using the revised head bolt torque specification below..."

    It does, in the 06-06-01-006C bulletin. I'll send the PDF to your email. The bolt torque pattern isn't specified, but it's the same as original.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  20. #20
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    As a "by the way", I couldn't resist watching one really short Youtube that was entitled "Remove the Duramax Damper Bolt in 2 Seconds".

    He used a 36mm socket and a ~24" 1/2" breaker bar, with the bar wedged behind the alternator pulley, held in place using bungie straps. Then, he got into the driver's seat and bumped the ignition key. The engine loosened the bolt.

    This seems more like a "here hold my beer and watch this moment", especially with a naked rear surface of the radiator in the video only inches away. I'd be wary of the engine starting with just a bump of the key.... then the loose tools would wreck the radiator, throw the wrench into a fender, then the windshield, then across the parking lot into your wife's car...

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