Hmmwv reliability

[Eric isley]

If the engine,transmission and transfer case was removed how reliable is everything else in a hmmwv?

 

[simp5782]

If the engine,transmission and transfer case was removed how reliable is everything else in a hmmwv?

Meaning you are going to put a different drivetrain in that has more power and more reliable will make the rest of the truck more unreliable for something it wasn't designed for

They are as reliable as the reason they were redlined and/or just surplus'd out. You can replace everything and it may last a million miles.

 

[Vapor Trail]

I am curious about this also. They've always had a reputation of breaking down all the time and being junk. When I tell someone who's been in the military about my project they say something similar

 

[Thumper580]

I own my second HMMWV... high maintenance money wasting vehicle. I can't say if they are inherently unreliable... Good maintenance will certainly go along way to reducing issues, just like any mechanical device. Wondering what the expectations were from the military... I'm sure it depends on the level of abuse.

 

[SmartDrug]

In my opinion, they get a bad reputation in service because they're generally maintained by relatively inexperienced mechanics and driven like hell by inexperienced drivers who aren't paying the repair costs- think rental car. When they hit the secondary market, they're a crapshoot. Now you introduce a ton of unknown with a vehicle many people don't have experience with, which functions quite differently from almost every other wheeled vehicle (portal axles, strange cooling system, everything tucked into the center tunnel, huge tire weight without solid axles, etc.).

I don't think they're inherently unreliable, but rather that they need sorting before they run properly, if you forego that sorting, stuff will break and possibly leave you stranded, hence the reputation. I know that on my M1123, I had a TON of stuff to get sorted, some of it took quite some time, I'm still not 100% done, and probably never will be. That said, everything I've repaired or replaced has been fine afterwards. Things will pop up, but that's the case with every vehicle. I've had FAR more mechanical failures with my wife's SJ Subaru Forester with 55,000 miles (transmissions, wheel bearings, brakes, etc.), than I have with my HMMWV.

YMMV, but I think that side of the reputation is largely undeserved. Now as far as it being slow, loud, obnoxious, ridiculous, and awesome, that reputation is well earned.

 

[glcaines]

Reliability issues was one of the main reasons they are being replaced by the military.

 

[Retiredwarhorses]

Reliability issues was one of the main reasons they are being replaced by the military.

Really? The hmmwv is 38yrs old…the JLTV is NOT replacing the hmmwv, it’s supplementing it, the JLTV has the worst
NMC rate of any vehicle ever rolled out, The Army moved JLTV funds to acquire more Hmmwv’s due to JLTV
NMC issues, so just how bad is the hmmwv?
oh, and the USMC isn’t set to retired the HMMWV till 2040

 

[Mogman]

Meaning you are going to put a different drivetrain in that has more power and more reliable will make the rest of the truck more unreliable for something it wasn't designed form

Is this from actual experience or are you just parroting what others have said?
This has not been my experience, also there is nothing inherently undependable about the HMMWV, most issues are from poor maintenance and neglect.

 

[98G]

Sample size of one...

But I've driven mine from KS to AZ to FL to KS to IL to WY...

@simp5782 has ridden in it in TN. @RGS20inophir has spent 700 miles or so in the (admittedly uncomfortable) passenger seat. @lindsey97, @AndyAK and @silverstate55 have all ridden in it.

And all I've done to it is change fluids. Mine is the gutless turd 6.2 and 3speed. Nothing special. Shows rebuilt in ME in 2004.

I was in the army when these things were new. They didn't seem unreliable in comparison to the CUCV platform.

 

[87cr250r]

The engine, transmission, and transfer case are the most reliable parts of the HMMWV. It's everything attached to those components that fails.

 

[blutow]

comparing them to a mass produced civilian vehicle probably isn’t fair, but I’d bet they aren’t much worse than many other American vehicles w 1980’s technology. Probably a little worse because of some of the odd (low production) systems the hmmwv uses, but in some ways they are simpler with less to go wrong. The engine/trans are old civilian tech and arguably more reliable in the hmmwv compared to their use in the civilian world (where the electronics on the injection pump were always failing). I’m very new to the hmmwv world, but have owned several old/classic vehicles and the hmmwv seems pretty middle of the road as far as common problems and price of parts. From a reliability standpoint, I wouldn’t hesitate to drive my 1123 across the country.

 

[Mogman]

comparing them to a mass produced civilian vehicle probably isn’t fair, but I’d bet they aren’t much worse than many other American vehicles w 1980’s technology. Probably a little worse because of some of the odd (low production) systems the hmmwv uses, but in some ways they are simpler with less to go wrong. The engine/trans are old civilian tech and arguably more reliable in the hmmwv compared to their use in the civilian world (where the electronics on the injection pump were always failing). I’m very new to the hmmwv world, but have owned several old/classic vehicles and the hmmwv seems pretty middle of the road as far as common problems and price of parts. From a reliability standpoint, I wouldn’t hesitate to drive my 1123 across the country.

Actually it could not be much worse than anything Detroit turned out in the early 80s, it was all junk.
The amount of vacuum crap ford and others put on their vehicles just to try and comply with pollution standards was a total nightmare, If you got 100K out if a GM product before the cam went flat or it just tossed a timing chain you were lucky, those were the dark days for sure.


EDIT, in fact the extended warranties came about because everyone knew they were building junk and it was the only way to get folks through the door.
The mid-late 80 ushered in the age of "electronics which made things SOOOO much better.

 

[TOBASH]

If you remove the engine, transmission, transfer case, you have an extremely reliable paper weight.

If you replace the power train with a non-standard unit, you create an unreliable vehicle as everything you do will be custom one off.

 

[simp5782]

Is this from actual experience or are you just parroting what others have said?
This has not been my experience, also there is nothing inherently undependable about the HMMWV, most issues are from poor maintenance and neglect.

first Off anyone here who follows different areas on the forum here will tell you I don't parrot jack crap. I'm the guy that will say I'm going do a total transmission type upgrade that requires new mounts, drivelines, cab mounts and 10days later that truck is rolling 1300 miles to flagstaff grossing 100,000lb. Not driving it around town scared to go 5mi cause of what might break.

I've built surplus trucks of all types & sizes. Upgraded engine performance then whole engines, transmissions, then transmissions not designed for the vehicle it was put in. Upgraded transfer cases etc. Suspension changes cause it was the next weak link. This is of course on trucks being worked. 6 to 800mi a day. Sometimes 1200mi in a day never shutting off for weeks at a time.

If they are a pavement princess or a show and tell queen they probably wouldn't ever have any issues. Normal daily and heavy use you will just go down the list of what needs to be fixed or upgraded. It's a never ended cycle on anything ran worth a crap. This goes especially true on the condition of the roads they are used on.

 

[DeMilitarized]

first Off anyone here who follows different areas on the forum here will tell you I don't parrot jack crap. I'm the guy that will say I'm going do a total transmission type upgrade that requires new mounts, drivelines, cab mounts and 10days later that truck is rolling 1300 miles to flagstaff grossing 100,000lb. Not driving it around town scared to go 5mi cause of what might break.

I've built surplus trucks of all types & sizes. Upgraded engine performance then whole engines, transmissions, then transmissions not designed for the vehicle it was put in. Upgraded transfer cases etc. Suspension changes cause it was the next weak link. This is of course on trucks being worked. 6 to 800mi a day. Sometimes 1200mi in a day never shutting off for weeks at a time.

If they are a pavement princess or a show and tell queen they probably wouldn't ever have any issues. Normal daily and heavy use you will just go down the list of what needs to be fixed or upgraded. It's a never ended cycle on anything ran worth a crap. This goes especially true on the condition of the roads they are used on.

I can attest for simp's knowledge. He took a stock m923 swapped the trans cause it failed to a 7155 cat trans then needed more power after driving thousands of miles and swapped the engine. Needed lighter bed sides and more fuel so put 2 hemtt fuel tanks on it and a mtvr bed on it. Upgraded the stock transfer case to a oshkosh 55000. Found out he needed a different spring pack so stole one from a wrecker and swapped it. This man is not afraid of anything as long as it makes practical sense. I think in his build thread he put over 200,000 miles on that m923.

 

[INFChief]

It’s pretty much all been said. HMMWV’s are very reliable if utilized as intended. My ass sat in the passengers seat of a 998 for 14 years. We all understand that these weren’t built for speed or extreme off-road use.
In any vehicle that is altered, particularly with higher performance applications, reliability is no longer a consideration until those mods have been thoroughly tested and results documented. What does that mean? Well, unless one is an automotive mechanical design engineer with particular expertise in engines, suspensions, drive trains, & steering, we can do what we want for modifications but if it all goes South it’s our cross to bear. IMH & uneducated opinion, the biggest challenge & the weakest links in the performance arena is the differentials and geared hubs.

 

[msgjd]

Actually it could not be much worse than anything Detroit turned out in the early 80s, it was all junk. Those were the dark days for sure.
EDIT, in fact the extended warranties came about because everyone knew they were building junk and it was the only way to get folks through the door.

it was also the era of GM's "0% Financing" national campaign, the first of its kind as I recall .. That got a lot of people in the door to buy .. A neighbor grabbed a couple GM pickup trucks for his business in '85 or '86 and soon enough had to ask me for rides from the dealership for either a recall notice or component failure .. Both trucks started to rot through the beds and fenders before they were 3 years old .. They were hauled to a boneyard in 1991. He never bought GM ever again. I bought a like-new '84 GM in '85.. Since 1993 it has sat under my pine trees with only 52k on it.. Never again.. As far as the M151 Mutt, being a M38A1 owner not long after I had enlisted I didn't care much for Mutts except what it had over the willys, road speed, impressive climbing ability, and off-road agility. .Always felt the Mutt should've had a low-range xfer case, though .. When the CUCV's showed up, we got the blazers first.. It wasn't long before they got parked 5 months of the year and the Dodge's were back in the "in" crowd. Bn Maint had a lot of problems with the GM diesels in the early years.. I was not a fan of the hummers either.. When they showed up, I looked one over and first thing in my mind was "how the heck is anyone supposed to get these wide cumbersome things into the tight places the Mutts have to go?" I never got to drive one and thankfully never rode in one.. Don't recall Bn Maint having trouble with them when new and I was "out" by 1991, but even so, I will stick to my old jeeps thank you very much.. They always do a lot of work for me and with tire chains go everywhere i don't want to walk .. Keep them clean, maintained, and unabused, I hardly have to put a penny into any of our stuff dated from 1981 back to 1950

 

[87cr250r]

I see a heck of a lot more square body Chevies on the road than pre-2000's Fords.

 

[98G]

I see a heck of a lot more square body Chevies on the road than pre-2000's Fords.

Yeah, they have a cult following these days.

But when they were new they deteriorated rapidly. You could watch them rust through in real time, like kudzu growing.

I didn't think much of the HMMWVs when I was in (the same time frame as msgjd), but I really enjoy the one I have now. It and my M925 are my two "never sell" vehicles.

 

[Ajax MD]

My observation is that the simpler models are more reliable. Anecdotally, it's stuff like the 4LE80 and it's control module that cause problems. I think I read that the 6.2L engines and some 6.5L engines had some deficient block castings that got better later.

I really agree with the statement about poor maintenance habits and abusive driving habits that give the truck part of its reputation. I have the best of both worlds- a good 6.5L engine with the purely mechanical TH400. I don't drive mine daily but when I do, I drive it like a work truck. The geared hubs add a layer of complexity that just requires maintenance.