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Agreed, it is an oil burner family of the least merit... bleck.
 
The HMMWV came with the 6.2 originally. That got replaced with the 6.5 Detuned (Naturally Aspirated) when they quit making 6.2's. The 6.5 TD was only used on up-armors and the heavy shelter carriers, in the Army at least. I believe the Marines got 6.5 TD's in more variants.

We still have them right now and I've rebuilt a solid dozen 6.2's in my time. In all reality they aren't bad at all. While they don't make the power that the modern engines make they are stupid simple and get the job done. Pretty much they work until they fail catastrophically. Very rarely do we have to do more than replace glow plugs, and I've seen many of them literally eat a glow plug and keep running. We had one we pulled apart that made it all the way back from Louisiana with a connecting rod bent almost 90 degrees. It just kept running up until we pulled it.

If it wasn't for the fact that "we" run them pretty much at redline down the interstate for hours on end they'd probably last a lot longer too. HMMWV's have 3 speed automatics and basically a 6:1 axle gear ratio for 37's. So yeah, ripping down the interstate with the speedo clear past the 65mph mark and down at the bottom of the gauge probably isn't the best thing for them. The newer HMMWV's do have 4L80's in them so they get a slight break in the rpm department, but we still pretty much redline non-stop.

IMHO though, its perfect engine for military use. It makes enough power to get the job done, its stupid simple, and doesn't need any electronics to run. The only thing electrical the HMMWV engine needs other than the starter is signal voltage for the fuel shut off solenoid. You can run a 6.2 or 6.5 a long time on just battery power. Wile having the OD gear is nice, for our purposes I prefer the TH400 over the 4L80. Again, because the TH400 needs no electronics what so ever. It basically works until it doesn't and its easy to replace. The 4L80's come with a TCU and solenoids that like to act up. With a 6.2/6.5 and a TH400 you could drive a HMMWV's through EMP central and keep on trucking.
 
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Its the one I want. No limp mode, no sensor acting up causing running issues, no need for a computer to diagnose why it won't run. If it has fuel and 24V going to the injection pump it'll run. Its that simple. They just keep ticking, even after that catastrophic failure. We've pulled 6.2 and 6.5's out of trucks that had "poor performance" to find broken connecting rods, cracked cranks, missing/broken pistons, nuts/bolts/or glow plug remnants fused to the head or piston, all kinds of crap. They still kept running and driving. They might be underpowered, but that's probably what allows them to keep running even when they're all jacked up.

All this fancy crap the Army wants to upgrade/ and replace the old trucks. In terms of a utility vehicle give me a plain Jane M998 HMMWV with a 6.2L diesel and TH400 transmission in it. Why? Because no matter how sad and dilapidated it might look sitting in the back corner of the motorpool, it'll start right up and get me wherever I need to go.
 
ah, when you says "catastrophic", you mean still running, albeit incredibly poorly. I mean parts and fluid everywhere, and backpack on.
 
The 6.2/6.5 doesn't make enough power to spew parts and fluid everywhere. :D

Even if it did, it'd probably still run. Don't get me wrong, its no 12V Cummins. But its one hell of a little trooper despite all that sucks about it.
 
Its all a matter of what you expect out of it I guess. Do I think a 12V Cummins is a better all around engine that's just as simple? Yes I do. However, a 6BT isn't going to fit inside of a HMMWV. They are too tall and too long to work in that chassis. The engine mounts completely behind the front differential, so even with the shorter V8 the rear drive shaft is really short and the front is a long 2 piece unit.

For a civilian type application I think the Duramax is a much better engine to have in the HMMWV. For the Army's purposes though I think the 6.2/6.5 works just fine and its ease of maintenance (especially in a field environment) is more important to me than power and fuel economy. I don't care much about longevity either because we can always just stab another engine into it. High mileage military vehicles still have well under 100,000 miles on them. Its just the nature of the game. We're talking about vehicles intended to operate in a field environment with poorly trained operators and mechanics. Not only are the mechanics poorly trained, but they're poorly equipped too. We don't need vehicles with powerful engines that can glide over the desert. We need simple, rugged, reliable. I'm a big advocate that the Army needs to go back to using nothing but M998 HMMWV's, the old 2.5T/5T trucks (but I'd settle for the 900 series 5T's sans CTIS), and then the Detroit powered HEMTT Wrecker. For our bigger transportation (line haul) companies the current Detroit powered M915/916 trucks seem to work pretty well. I'd even settle to rip the CAT engines out of the FMTV's we run now and replace them with mechanically injected Cummins engines. We can keep the electronic shifting Allison's because honestly those don't seem to give us too many headaches.
 
crappy is all relative... for $2k with a bunch of TnT underneath, if the unibody isn't crapped out, it aint a bad deal.
 
Makes sense. If I had the cash at the time would have probably jumped on that one.
 
unibody cracks will be toward the front then, steering box unless the fairly beef front bumper covers that area. Looks like a TnT rear bumper too...
 
xj-grin said:
unibody cracks will be toward the front then, steering box unless the fairly beef front bumper covers that area. Looks like a TnT rear bumper too...
Click to expand...

It is, rails, front and rear bumpers. Their first gen winch bumper was very reinforced. So the front is likely okay.

tnt_xjrockrunnerfront.jpg
 
e497b8f210c56dd08cd7a24646aa9357.jpg


Still on their website for the y- link. I wonder if people are swapping the best parts off, then selling what's left. Looks like the shocks have been changed, and I doubt the original rig had a Lincoln locker.

Sent from my SM-N920P using Tapatalk
 
yeah, surely it had better axles at one point. Still, for a full y-link, frame plating, sliders and front and rear bumpers... there is alot still right with that rig, even if rode hard and put away wet.
 
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