A new section...HEMTTs

I know not many have HEMTTs, but hey, I'm starting to see them pop up on GL. I have some good knowledge of the series of trucks since ive been on active duty. I'd be happy to share as much as I can with anyone who'd like to know more, or have performance questions, especially that old dog of a motor the 8V92.

I second that - there are a few lucky ones here who own them and can utilize your expertise.

Okay, first question or observation. Noticed on GL related postings here or postings about HMETTS that there is always alot of surplus, (new and used) cabs about for these trucks.
Why?

the cabs ar GL come off the trucks that get the armored cab. It's a whole new cab assembly..

A few months back a hemtt wrecker, the M984A1 came up on GL. I'm watching every day, even deployed ((i have the most understanding wife on the planet)) for another wrecker. I have business plans for extreme duty recovery when I return from Iraq.

But yes, any questions or concerns relating to 800 series 5 tons, hmmwvs, hemtts, hets, super hets, m915s, 900 series 5 tons, fmtvs, lmtvs, the first of which are starting to filter down. I'm what was originally a third shop mechanic s i have alot of experience in drivetrains, and have come up with a few tips and tricks.

did the army have a problem with fuel getting in the oil with the 8v92, if so what was the cause and the fix, im thinking it was the fuel lines on top of the head to the injectors

I second the HEMTT column request.
Signed, the baby HEMTT... and his boy, Jones

Continuing with the logic in the current forum, I would suggest changing "5 ton and up" to just "5 ton" and then maybe add something like "10 ton and up" to include M123, M125, M911, M915-M920, LVS, HEMTT, PLS, etc. or maybe even "7 ton and up" to include the MVTR.

73m819, let me answer your question like this.

Assuming your not having difficulty starting the 8V92, but there is a definitive amount of fuel in the oil ((often not only can it be smelled but the oil, level consistently seems to stay at the same level, for those familiar, by design this engine uses oil at a rate of 1 quart for every tank of fuel, it's due to the 2 stroke port configuration wiping oil from the rings, and the seepage from oil getting past the rotor vanes on the supercharger next to the gearcase on older engines.))

If your engine is *easy* to start, but is obviously passing fuel to the engine oil, your first check is in fact the injector supply lines under the rocker covers.

If the engine seems to be difficult to start cold, or is cosistently lacking power, then it is also possible you have a faulty injector(s), which if your familiar with the 8V92, if the injector is not spraying, but is streaming out fuel, it will simply wipe the oil from the cylinder wall and will not build enough compression to start the engine without cranking over and over and over, this fuel must go somewhere...right down into the crankcase.

If the second is the case, before suspecting the injector itself ((very unlikely on this series engine))you should check it's timing with a depth gauge, off hand i do not know the depth it is supposed to be set at ((Something like 1.465" don't quote that, ill verify in a few days))

But scratch all that for now, let me give you a flow chart to go off.

1.Does engine start easily.
2. ASSUMING it does, take off your rocker covers, start engine and idle, this is a great time to check your lines, they will visibly drip at the fitting if they are leaking, they are also made from stainless and quite brittle, so if you must tighten them be careful for twisting, there are three variations of the 8V92TA I know of, with small design changes in everything from fuel pumps to the materials used in injectors and lines, even the crankcase breather tubes, slobber vents and so on, so if you have difficulty send me the serial number of your truck ill look it up.
3. If you find NO leaks, there are two versions of this particular engine, one was a design flaw of the fuel pump, if the pump bearing went bad, and blew the seal it leaked fuel into the engine, at the same time an additional symptom was the engine to not start after sitting for some time. Then when investigated, the fuel filters to be empty. ((we corrected that in a pinch by using compressed air in the fuel tank itself to forcefeed the system))


Things CAN get complicated, but I think you hit it on the head, especially if it feels like one particular cylinder or part of a bank of cylinders just isnt getting all the fuel the rest are.

Look for a slight leak, it's gonna be a hard drip to find, but then again I highly doubt you use the Hemmt like soldiers do, and this is an engine suspect to wet stacking moreso than any other engine in our current fleet. Your best bet if you reach no conclusion is to literally take it out and run the ever loving *ell out of it and *if* it is leaking fuel it will be evident surely upon your return.

Sorry for my rambling, my thoughts can be hard to follow, but yea...that should be helpful.

my 8v92 is in my xm977, it had the making oil problem when i bought it, that is the reason the old owner shut it down, im told that it had good oil pressure and power, just started spitting out oil, its high on the dip stick now, i have not had time to work on it so far, it needs a starter and alt.

the xm977 is PRE hemtt, it is a prototype hett (or something like that)

I've thought about making the suggestion of a hemtt section or 10ton-up section- as long as it gets some use. I know I've always got something to say about them - being knee deep in restoring one right now.

I don't check GL much, are there hemtts coming out as surplus? I was under the impression that it was mostly just cabs and wheels and such. Isn't Oshkosh still sucking up most of the damaged/wornout trucks for their RESET program?


Lets give it a try.

hemtts fall through when they dont meet the requirements for rebuild, however the only vehicles that dont qualify is the patriot missile tractors, the m978 cargos and original M984s OR m984E1 NOT the A1, I've seen all of the above on GL, usually from depots or reserve units where the machine has sat for several months or years.

I've seen maybe five HEMTTs on GL over the years. They ranged from a wrecker with a broken boom that ran to a cargo that was rolled. The rolled truck was probably only good for parts. The best way to get a HEMTT is to build one. There are a few parts trucks in CO (on another post) that could probably be pieced together. I was building an M978 until I stumbled upon my M977 for sale.

I recall Cabell told me in November that there were a few HEMTTs sitting in the Fort Bragg DRMO yard that were going through the screening system. Hope they come up for bid! (not that I'll be bidding on them, I just like seeing big iron get auctioned off)

With the newbies bidding things up these days, trust me, they will go high! I am watching today's auctions and it shocks me what they'll pay. I wish I could get their contact information. It sometimes seems as though people want to pay more on GL than they do through other retail avenues.

I spoke with the GL rep at the site here at FT Jackson and he told me of a HEMTT that was auctioned off yrs ago that was rolled. The buyer was Australian and paid over 60k for it then had to find a way to ship it there.

army_greywolf said:

I know not many have HEMTTs, but hey, I'm starting to see them pop up on GL. I have some good knowledge of the series of trucks since ive been on active duty. I'd be happy to share as much as I can with anyone who'd like to know more, or have performance questions, especially that old dog of a motor the 8V92.

Click to expand...

I know this is an old thread, but now it is even more relevant! If we take all the HEMTT owners, and add those MK, and PLS guy's. Maybe lump in the others that own anything with a 8V92, we should have a great group to share in a dedicated section here. I know the push back from the ones that actually hold the site together here is that would be ALOT of work to separate all the history, but I say we start somewhere and make it work over time.

I have to of these beasts and would like to see a category for them!