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Thread: Help with M998 purchase on engine

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    Default Help with M998 purchase on engine

    Have 2 M998 in mind for same price and basic condition. All things considered to be same on same with the exception of diesel motor. One 6.2L, the other one a military rebuilt 2010 6.5L. Does anyone have any guidance. This will be a fun family vehicle, drive on beach, around town etc. Trip to beach will be maybe 1.5 hours to get there. Just simply asking if everything was in identical condition, which motor would you run with, and why? Thanks. New member.

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    4 Star General NormB's Avatar
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    Hoo-boy.

    ALL other things being equal, probably the 6.5 IF there's a 4-speed with it.

    This topic's been beaten to death and the only thing I can find - consistently - favoring the 6.5L optimizer NA motor is the extra power.

    I've read a number of reports about NEW 6.5L NA motors detonating. One favorable feature seems to be a single belt model is preferable.

    But the weight/power ratio is still low when you consider the mass of the truck.

    Me, I'd probably go with the 6.5L only for the marginal performance gain and purported longevity. Loaded with family and beach gear you might want to get an AC for it and the extra power from the motor will be needed to run it and the 200A alternator.

    Stick around, there'll be other opinions.

    I'll make popcorn.
    A day without rivnuts is like a day without a Humvee mod.

    MEP-802A TQG 04-2016
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    M1038 W/W 6.2L NA 9-2016
    MEP-803a TQG 09-2018

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    Thanks and would love to hear other thoughts. I assume this is a 3 speed, image of the 6.5 rebuild I am interested in. If the 6.5L is a military rebuild, does that mean the number 8 cylinder issue has been "fixed" so to speak? I looked around the Forum to find past posts like this but did not see anything that directly correlated. Also, "DETONATE?" UMM BLOW UP?
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    4 Star General NormB's Avatar
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    Quote Originally Posted by NCarolinadawg View Post
    Thanks and would love to hear other thoughts. I assume this is a 3 speed, image of the 6.5 rebuild I am interested in. If the 6.5L is a military rebuild, does that mean the number 8 cylinder issue has been "fixed" so to speak? I looked around the Forum to find past posts like this but did not see anything that directly correlated. Also, "DETONATE?" UMM BLOW UP?
    Yep, that's a 3-speed. DoD wound up just swapping out 6.5 engines for 6.2s as time went by. Detroit Diesels then GEP motors (more desirable) and yeah, "detonate" is a general term for total internal destruction, or otherwise broken beyond repair.

    That #8 cylinder thing I read about, not very versed in it; I THOUGHT after what, Dec 1999 or something all 6.5L motors had the boss reinforced, problem taken care of, but you'd have to dig around a bit.

    I'm pretty happy with the 3-speed so far. I don't even feel it shifting but have a tachometer cheat sheet to tell me approx. MPH with engine RPM and it matches that pretty well. I don't take it on the highway (often, or much) and don't really intend to when I get it to its final home in Hampshire, TN in a couple years (farm, retirement property).

    Would I have LIKED to have had a 4-speed? Maybe, but I don't feel comfortable at higher speeds in these things, in the words of one wag, "driving 55mph in a HMMWV is like riding the space shuttle down from orbit." Maybe so. 45-50 mph suits me fine. But that 4th gear drops the RPM a lot, less wear and tear/heat/noise.

    And don't forget, they're LOUD! Like aviation intercom/headset and/or earplugs LOUD!

    Keep looking around, don't rush into anything you might regret later.

    Choose carefully.
    A day without rivnuts is like a day without a Humvee mod.

    MEP-802A TQG 04-2016
    1992
    M1038 W/W 6.2L NA 9-2016
    MEP-803a TQG 09-2018

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    Preference for 6.5 GEP variant. Otherwise no preference between 6.2 and 6.5.

    In general, choose any truck based on overall condition before looking at trivial differences like NA 6.2 to NA 6.5.

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    My budget is around 21k so I am not looking for a total fixerupper. There are a few on ebay in this range now but not sure where the market is so a little apprehensive in pulling the trigger.

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    My budget is around 21k so I am not looking for a total fixerupper. There are a few on ebay in this range now but not sure where the market is so a little apprehensive in pulling the trigger.

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    If you have a fakebook account, there are MANY HMMWVs available on the various FMV groups like "Hmmwv swap meet" HMMWV and a few others I'm not connected to. I've seen some smoking deals come and go.

    Your price isn't unreasonable, and from what I've seen, about a year or two after people have invested blood, sweat, tears and their children's college funds in these trucks they often sell for very reasonable prices with very good upgrades (high back seats, better tires, airlift bumpers and RICO spare tire carriers), lighting, generators, better soundproofing, X-doors and more.

    One ad I saw was for TWO for $32k, one slantback the other a plain M998.

    There's a refurbished one for sale near Richmond VA for about $16k.

    Give it a look.

    There are SS members all over the country who might be convinced (many have offerred) to take a look at trucks you're interested in (gas and lunch money deals, some more commercial), but as much as I've seen several "sight unseen" deals that were awesome, I personally wouldn't take a chance now, especially knowing what I DO KNOW now.

    Again, take some time, good luck, and come back and post pictures when you score.

    Norm
    A day without rivnuts is like a day without a Humvee mod.

    MEP-802A TQG 04-2016
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    M1038 W/W 6.2L NA 9-2016
    MEP-803a TQG 09-2018

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    Can you elaborate on NOT TAKING A CHANCE NOW? Ate you saying you would not go the M998 route if you had it to do all over again. Can you elaborate?

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    4 Star General NormB's Avatar
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    Quote Originally Posted by NCarolinadawg View Post
    Can you elaborate on NOT TAKING A CHANCE NOW? Ate you saying you would not go the M998 route if you had it to do all over again. Can you elaborate?

    Sorry if that was confusing.

    I'd buy again, but I'd go over the truck with a fine-toothed comb. One of those "wish I knew then what I knew now" things.

    The one I bought had a cracked 218 transfer case and two bent wheels (just enough to make some road noise). Xfer case likely due to forklift handling at DRMO, I replaced it - while I replaced fuel hoses, seals, sender - with an NP242. Quieter, smoother.

    I think what I meant was, I don't think I'd trust someone ELSE to look at the truck for me unless it was someone who did this professionally - and there's a LOT of guys who do.

    Friend of mine - who goes by "AOR" on this board - bought a 1986 M998 which had a frame-off restoration up in New Hampshire (or Mass.? IIRC) in 2012, 6.5L GEP, 3 speed, 100A alternator, clean, new wiring harnesses, very nice deal and he bought it after we looked at pictures, friend of his hauled it from Iowa to Maryland. This was about a year ago and I THINK he paid around 14k for it.

    There're some guys who offer inspection services, you'd have to poke around the board to find them, Jeff (who runs an off-road JEEP shop) has a customer who was a former Army mechanic at Ft. Meade and he took a look at his truck when it got here and was impressed.

    Like I said, there are some deals to be had, and some buyers to be "had" as well.

    I'd been looking into buying one for about a year, six months on the SS board reading what I could, thought I had a good deal.

    Could've been better. But several hundred hours and a few thousand dollars in parts have it SO much closer to what I want and it's my dog's favorite place to sit in the house/garage so I couldn't possibly ever sell it.

    One suggestion I make to most everyone is, start reading through the "What I did to my HMMWV today" thread. Several hundred posts, many you can blow over, but there's a LOT of nuggets in there you don't want to miss.

    Norm
    A day without rivnuts is like a day without a Humvee mod.

    MEP-802A TQG 04-2016
    1992
    M1038 W/W 6.2L NA 9-2016
    MEP-803a TQG 09-2018

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