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LZ9 3900 leaking head gasket options

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  • LZ9 3900 leaking head gasket options

    Well guys it's finally happened, the LZ9 in my lightly tuned 2008 Uplander Cargo Van has developed a noticeable oil leak from the rear head. Residue had been building for some time but now the oil pan is saturated and the constant saturation even killed an engine mount. I even had a local shop double check the source of the oil leak without telling them my suspicions.

    The engine has been pretty flawless over the last 5 years and now has 188,000 miles, so the only options worth the time and money for me ($1700 head gasket repair is not a worthwhile option IMO and I'm not even going there lol) is to keep driving it and keep some cardboard under the van until I get the time and money to do a lower mileage engine swap since it's just a very lightly modded daily/work vehicle with an Overkill tune and Dryflow panel intake filter.

    So my questions to you more knowledgeable 60 degree guys are these-

    1. Once I get the funds to purchase a low mileage 3.9, with the vehicle being a 4400lb/4 speed auto van, would it be worth considering the better flowing top end LZ4 intake manifold? Even after pouring over pages of old 3900 related threads, I'm not clear on how much torque/power loss under the curve there could potentially be without the variable intake manifold that my LZ9 has. The LZ9 is a decent spunky engine in such a chunky van but of course if I can make it more fun to drive, then great!
    Obviously I'll likely need a retune if I ditch the variable intake. Even though it's a van, I like to somewhat enjoy whatever vehicle I own but I also don't want to create a gutless wonder with noticeable lowend torque loss and end up slower than stock.
    For whatever it's worth, I have an Overkill tuned PCM and TCM. The tranny is much more aggressive holding gears and downshifting which really transformed the driving experience...for a van at least!

    2. With the 3900 head gasket leak potential on any used engine, would you recommend I get new head gaskets installed prior to dropping another used engine in? This won't be my first used engine install but I'm not a machinist/pro mechanic like you guys and I work 60+ hour work weeks so I'll need to trust a gasket replacement to someone qualified.

    Being a work van and staying busy I'd prefer the fastest option and just drop another engine in but playing Russian roulette with another engine/potential head gasket leak really worries me.

    Just looking for some input from you guys that have experience with the LZ4/LZ9 head gasket replacements and/or guys running forced induction with these engines.

    Thanks!!

    Jeremy

  • #2
    I wouldn't bother with the better flowing intake, you won't notice a difference in power

    if picking up another used engine, a compression or leak down test would help determine if you had a a bad head gasket. if the tests are good, I wouldn't bother swapping gaskets.

    seeing as this is your work van, you prob don't need to spend the money on mls gaskets. I have seen some cheap top end gasket sets for the lz9 on ebay for under $100

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    • #3
      I appreciate the insight! And to clarify, if I were to try the LZ4 intake, I would couple it with an upgraded cam. And even though it is a work van, it also serves as my daily driver so I don't mind playing with the engine, etc to improve the driving experience where possible.
      I'd even try an LZ9 VVT cam if I could fine one.

      Thanks again

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