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How many miles is an M35A2 and A3 good for?

alfred10

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How many miles is a M35A2 and A3 good for before you need to replace or rebuild the engine, transmission, suspension, etc? I was worried becuase I see many that have so few miles. It seems like motors are rebuilt at 10k miles... If I drove one once a week 200 miles would it hold up?
 

Carl_in_NH

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Wilton NH
It all depends on how it's maintained, and how well it is treated; beat the snot out of it, and it's not going to last from here to the corner gas station. Take care of it, and it should last a very long time. You'll likely find that something you own and have to maintain with your own sweat and dollars will last longer than something that's driven hard and owned by the government.
 

wreckerman893

Possum Connoisseur
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The M35A2's were (IMHO) the most bullet proof truck the military ever bought.
They could, and did, take a lot of abuse from soldiers that drove them.
I started driving them in 74 and they were still in the inventory in 07 when I retired.
Quite a run for an old steel soldier.
The A3's were a futile and expensive attempt to modernize them and appease the environmental Nazis who think black smoke is an abomination.
If you get an A2 that is low miles and has not been abused there is no reason the old multi-fuel engine and the driveline should not last over 100,000 miles if you take good care of it.
I have two deuces and a M275 tractor and I will never own an A3 because it violates the KISS principle.
One day the military will rue the day they bought overly technical and overpriced vehicles.
 

saddamsnightmare

Well-known member
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Abilene, Texas
February 6th, 2010.

Between you, I and the rock, I think that the M35A2's with multifuel engines get too bad a rap. The trucks were designed to be simple, repairable, and if driven with some respect for the vehicle, indestructible. Probably the two weak points in the design is the dry (oilless) start (correctible with JATONKA's filter adapters) and the foot long driveshaft between the transmission and the transfer case (a real pain to get at, and you must keep the bolts in it tight!), and perhaps the single circuit brakes. However the truck went over 60 years in service in its various iterations, so there must be some good in the design.
In this, I concur with Wreckerman893, BUT if you rock crawl the truck mercillessly, and do not respect the maintenance, you're gonna be in for quite an experience! The Unimoggers who abuse the S404.114's rock crawling find that the design, while nearly bulletproof, is not FOOLproof, as their trucks are showing failures of the frames and drives almost never seen in the 60 years of that design's existence....... I have seen civillian trucks of the same design era chug on with minimal maintenance, so the deuce with care should outlast its owner. Just my two cents worth.

Cheers,

Kyle F. McGrogan:p

NB: IT is, however, also not intended as a high speed road truck..........:?
 

LanceRobson

Well-known member
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Pinnacle, Stokes County, NC
Preventive maintenance is the process of checking, adjusting and renewing components BEFORE they break or wear out.

The TMs for vehicles of the M44/M35 era were written with two major thoughts in mind; maintaining the vehicle so as to be able to operate it in an austere environment fo 60-90 days with a minimum of major breakdowns or time consuming repairs and, second. an assumption that the PMCS would actually get done "by the numbers"

As such many check, services and parts replacements were specified at time intervals and wear limits that are much more conservative than most of us need to do.

Since few if any of us have the resources, including time as a resource, to follow the GI PMCS and scheduled maintenance regimes we have to determine for ourselves which to do and when.

With a well thought out maintenance program that reflects our own use, budget and tolerance level for surprises, any of these trucks can be kept reliably running for a long time.

Mechanical equipment (trucks, tractors, old engines) that sits around and only get occasional use has problems and stresses different from equipment that gets frequent use. Often things like seals that lose resiliency due to non-use, internal corrosion due to condensation, fuel and lubrication systems gumming up from non-use etc cause the premature failure of components and lead to low mileage replacement.

Driving it once a week, even if only a dozen miles will do wonders for the truck's longevity and durability. It will keep all the seals pliable, keep the fuel system flushed, dry the condensation out of the engine, exhaust, transmission, transfer and axles, keep the batteries healthy etc.

Another important consideration would be that in seeing and operating the vehicle often it is that it is much more likely that you'll spot, hear, smell or feel a problem while dealing with it is only important and before it becomes urgent.

Lance
 

emr

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landing , new jersey
I do not think they get a bad rap at all, they are awesome.and will outlast us, now remember driver error, no PM no motor .thats up to U, they may very well be the longest production and longest lasting tactical vehicles as a whole ever built, all parts included ...A fool is soon parted with all they have, learn what a tactical vehicle are and what it takes to own one, U are on the right track....good luck drive alot, she wants to be driven and cared for, all nuts and bolts and I mean ALL need to be tightend and retightend, read the guzzilion posts about PM here and the deuce , and U will be one of the In the Know guys too.......:grin:
 

BKubu

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Gaithersburg, MD
David Doyle once posted a report generated during the Viet Nam War that summarized the longevity of the M44 series. Basically, the report stated that M35s required motor overhauls at around 10K miles. Admittedly they were used very hard.

If I had to have a truck start up once under terrible conditions, I would take an LD/LDT powered M35A2 hands down over the CAT motor in an A3. If I needed to get a lot of mileage out of the motor, my vote goes the other way...I'd rather take the CAT motor over the LD/LDT any day of the week. I will also add that I started my A3 at 0 degrees with no trouble, but I did give it a little sniff of starting fluid.
 

kc5mzd

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Texas
If I drove one once a week 200 miles would it hold up?
I would never buy a M35 expecting to drive it for 200 miles once a week. They are very durable and nearly indestructible when taken care of.
They are geared very low and are not made to go very fast. Most have an average speed of around 20mph. (take the hours and miles and average them out).
I have several with 9r20 tires they do very good at around 30mph. With 11r20 they do good at 35mph. Top cruising speed is around 45mph.
On a diesel (including multifuel) the maximum extended cruising rpm is about 80% of the engine's rated maximum rpm.
The multifuel max rpm is 2600 X .80 = 2080 MAXIMUM cruising rpm. If you want to have it last a long time with minimum maintenance I would keep it under 1700 - 1800 rpm.
They are very cool trucks and if you go into it realizing you are getting an antique and drive it accordingly it will surely outlast the driver with minimum maintenance.
*** They suck on the freeway on 200-mile trips ***
 
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kc5mzd

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Texas
If I needed to get a lot of mileage out of the motor, my vote goes the other way...I'd rather take the CAT motor over the LD/LDT any day of the week.
Your CAT will blow up if you drive it for 10k miles at 2500rpm like they do the multifuel. I have a CAT in my work truck. It is an excellent motor. It has over 1,000,000 miles on it and it runs better than most new trucks. The key to a CAT is to keep the rpm low and use the low-end torque they are famous for. I rarely rev mine over 1500rpm when accelerating. When cruising on the freeway it runs about 1200rpm at 65mph.
The A3 will never live up to the potential of the motor because they are using the engine for something it was never intended for.
 

BKubu

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I just posted on another thread that the A3 is not as "fast" as an A2. They are quicker, but their top speed is lower. The A3 runs comfortably at about 48 MPH. In order to do 52 MPH, you are running about 2,500 RPM. The motor (data plate) and the manual say that is fine, but it seems a bit fast to be running a motor that I hoped to keep for a while.

I am curious to learn more about your statement: "The A3 will never live up to the potential of the motor because they are using the engine for something it was never intended for. " I am not saying I disagree...only that I would like to hear more about this. I owned an A3 and put a lot of miles on it. I never operated the vehicle in any manner that I believed would reduce the potential of the motor. I followed the correct start up and shut down procedures, properly serviced the truck, drove the truck slower than indicated in the manual (i.e., less than 50 for the most part). Again, I am not disagreeing with you, but I would like you to explain this a bit more as I don't understand.
 

tm america

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this is getting interesting ?I somehow must be missing something .The engineers that made these engines tested and know the limits of the engine they set the governed rpm less than the limit of the engine.military trucks are rated way less than what they can do. they re rated at 100% duty cycle. i agree running it at half the rpms will double the life of the engine but the fact it is only running at 2600rpm to begin with would give you double the life of a gas engine.
I just cant see driving a deuce at 45mph on the freeway . ok maybe backing off to 2400-2500rpm but even that is not needed. i have been running mine balls out for 7-8yrs and about 7000miles i have put on it .no problems .I think one of the biggest things that effects the life of a multifuel or cat in an a3 is history.These are combat trucks drivin by 18yr old soldiers that don't own them and drive them like they don't own them .
You can drive it as slow as you want but if it was submerged or over reved not maintained by the army it is not gonna last long for you.Buyer beware;)

do tend to agree the multi will last longer in a deuce than the cat as the power band is better matched to the drivetrain and this makes a big difference in durabilty.i personaly don,t like cost of fixing the cat motor vs the multifuel.
 

kc5mzd

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The CAT motors are engineered to produce more low end torque.

stand by searching for more data......
 

kc5mzd

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There website ohe.cat.com is down. Some other time you should go and look up the 3116 engine to see what the manufacturer says about running them at 2500 rpm. I will check up on them later. If I owned one I would look up what CAT rates them at and run it a little slower. The military rates them diffrently because they can afford to rebuild them at 10,000 miles. I think they should last for 500,000 miles if you take it easy on them. My work truck has a 350hp CAT. I bought it at 800,000 miles. I have driven it for around 250,000 miles and it still runs great and has less blowby than a brand new Detroit or Cummins of similar size.
 

Westex

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El Paso, TX
My 2 cents is that keeping the rpms down on the multifuel is the key to longegivity. If I want to speed, I'll take the jet.
 

bassetdeuce

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My 2 cents is that keeping the rpms down on the multifuel is the key to longegivity. If I want to speed, I'll take the jet.
I agree, but on our interstate system, a good deuce speed of 45mph can be downright dangerous or illegal. Secondary roads often have you zig zagging all over the map, adding a lot of mileage on a trip.
 

kc5mzd

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They didn't have much info on the cat 3116 engine on their website. The C7 is the closest match that has detailed info. CAT recomends C7's be setup to run at 2000rpm at 60mph with a max cruise speed of 65. This is where the designed application and the military's use differ. This is why I don't think the CAT engines will ever live up to their potential in the A3.
 

kc5mzd

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The reason diesel engines run at lower maximum rpm is because they have a long stroke. This requires longer connecting rods, longer throw on the crankshaft and heavier connecting rod ends on the crankshaft. This gives diesel engines a very heavy rotating mass that can’t spin as fast as a similar cubic inch gas engine. They do this because diesel burns slower than gas so the longer stroke is required to allow time for all the fuel to burn and expand in the combustion area. Gas burns fast so gas engines have short strokes that take advantage of the rapid expansion of the air - fuel combustion.
Here are some specs from a few similar cubic inch sized engines.

Chevy 454 (gas)
454 ci
bore 4.250"
stroke 4.00


Diesel
ldt 465
478 ci
bore 4.56
stroke 4.87


CAT 3116
403ci
bore 4.13
stroke 5.0


Even though the CAT is smaller in cubic inches than a gas 454 the stroke is a lot longer. This is why the diesel engines have to turn slower than gas engines. Also the CAT has the longest stroke of the three. This will give it more low-end torque and better low rpm fuel economy. Also running at low rpm the Cat would likely outlast the other 2 engines. It would also most likely self destruct at 2500 rpm before any of the other engines that have shorter strokes.
 

SpyDad

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Springfield, MO.
Ok Car_in_NH I believe there is hope for my 71' deuce. I recent bought my first one and it has 84,000 miles on it. I can't remember the hours as I sit at this computer, but it runs strong and fires right up. Unfortunately I did not get any logs with it, but it appears to be in good shape. I have had it out for a number of drives, seems the average speed is around 45 - 50 mph at about 2,000 - 2,200 rpms (doing my best to remember).

I am doing a lot of forum reading and reading the manuals from the resource pages to learn as much as possible about it before I even take a wrench to it. Thanks for sharing everyone! :razz:
 

m35_military_parts

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Michigan
I just finished my bobbed M35a3, and I love it! I put 48in tires on the truck. The truck drives 55 mph at 1900 rpm, and 65 at 2400 rpm. I'm also getting 16 mpg driving 55 mph. With the larger tires I was able to lower the rpm's so the longevity of the engine will not be an issue. The Cat 3116 is used in boats that run wide open at 2400 rpm constantly. Boat manufactures would not put a engine in that would not handle those conditions. I know people will disagree, but most that do have no experience with the engine, and go off hear say. :deadhorse:
 

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