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M1070 Tech & Tips

goodguyzy

Active member
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medford oregon
I gained so much knowledge on the M916-M920 tech and tips Im starting this one on the HET.
First project was to modify the filler hose the truck came with. It only came with a 10' hose, not enough to reach the rear tire on one side and not enough to reach the front on the other. Added 50' hose so I can also reach the trailer and put in a coupling on the end so I could connect air tools.

Next project: replace 5th wheel hitch with 2" slider closer to rear so I can tow civy lowboy.
 

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goodguyzy

Active member
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Location
medford oregon
OK, Ok......Well im working on the fifth wheel project. I scored a slider off a wrecked truck, I plan on moving the center back aprox. 3 feet or 64" to center from rear or center of the back two axles. Two problems ive run into are the fitting for the rear steering box sticks up above the frame and the mounting for rear axle is also in the way of the angle mount. To solve this problem Ive made new angle brackets from a M35A2 frame that will bring up the mounts 1 1/2" to clear the fitting and provide strength for the square that needs to be cut out for the axle mount. Here are a few pics so far, I don't have a bunch of fancy fab tools and nice shop like some of the other members here but used a skill saw with metal blade to cut the frame and a hand held drill so far. I will be finishing project in the next few days and will post up more pics.
 

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Danger Ranger

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Roland, IA
Lol, that dog looks terrified of the giant, towering thing behind it...hahahaha.

I will follow along for some knowledge I suppose...good luck.
 

goodguyzy

Active member
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38
Location
medford oregon
Done with the new 5th wheel (fontaine slider). Ended up being a lot more work than thought. (the usual) Im not going to install air switch on dash but put on a air hose fitting to connect air hose to as im not going to be sliding the wheel that much. Also replace air coil lines that supply trailer. Note that just to match what was there I installed the 40" leads that are longer than normal. Im not sure if they will reach and may have to put on couplings and add a standard set. Next project is to take care of some rust spots and get it to hold over till next year when im going to repaint in good weather. Or cb or radio? Lots of stuff to do.
 

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goodguyzy

Active member
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medford oregon
Its 59", two inches higher than the 916. Should be able to uncouple trailer and couple back up easily. Also have done the same conversion on 916 btw.
 
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Castle Bravo

Hundredaire Socialite
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I don't have anything to add yet, but I do have a question.

The 1070 LO calls for 15w40 engine oil, but I've seen and heard many people say that 2 stroke Detroits should only be run on straight 40 weight oil. In the maybe several thousand miles I may put on this truck, am I going to see a difference between 15w40 and SAE40? Like many things, its easy to justify something that ultimately might have little to no real world difference, and the fact that you spent some money weighs in on your observation as well.

Anybody have any experience with this?
 

HETvet

Member
395
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18
Location
Bedford, texas
I don't have anything to add yet, but I do have a question.

The 1070 LO calls for 15w40 engine oil, but I've seen and heard many people say that 2 stroke Detroits should only be run on straight 40 weight oil. In the maybe several thousand miles I may put on this truck, am I going to see a difference between 15w40 and SAE40? Like many things, its easy to justify something that ultimately might have little to no real world difference, and the fact that you spent some money weighs in on your observation as well.

Anybody have any experience with this?
First a little about my self; 8 years active duty army 88M, with 5.5 almost 6 years of that being a HET operator. 96th TC have been my company for 5 years. This company IS the us army's premier HET company as its THE most deployed unit is the US army, period.

Yes the LO does call for 15-40. State side we do run that oil. The problem with this lubrication is that in a hotter climate and under heavy work loads, for long periods of time the motor oil gets to thin and can drop oil pressure down to 0-3PSI during operation. To fix this condition, we switched to 40wt engine oil and by passed the motor oil passages at the clutch fan. Now we show 60PSI during operation.
 

HETvet

Member
395
6
18
Location
Bedford, texas
My experiences and Knowledge with 5 years of experience with these machines

The intent of this write up is to share my extensive knowledge and personal experiences with the community. Please forgive me if there are any grammatical or spelling errors, my focus is to get this information out there. Moderators please feel free to edit my post and correct any found issues. This information is in no way intended to supersede any and all applicable TMs and FMs. Any modifications performed on your vehicle are performed at your own risk. Lets begin......

The M1070 was built as a heavy hauler and is best paired with its M1000 low boy trailer. This combination completes the system. The M1070 is 49,000 LBS, powered by a Detroit Diesel 8V92; 2 cycle, V8, Turbo charged and supercharged Diesel engine. The transmission is a unique Allison Unit. What make it unique is the automatic gear splitter, also known as intermediate gears. With the gear selector in 2-5, comparable to D in a regular automatic vehicle, the transmission will select 2nd gear, and work its way through the ratios from there. 3rd,4th, and 5th gears will utilize the automatic gear splitter. For faster standing acceleration, and when towing heavy loads, the operator should manually select 1st gear. Once the tachometer reaches the YELLOW line, manually shift in to 2nd gear. Again, when the tachometer reaches the yellow line, manually select 2-3. It is at this point the operator need to be aware of the automatic gear splitter. In 2-3, the tachometer will reach the yellow line, and at this point will automatically shift. After this shift, the tachometer will reach the yellow line again, and the operator at this point should manually select 2-4. This process will continue to happen for any gear after 2nd. It's highly recommended to always manually shift the transmission while loaded.

On the cat walk, you will find the winch controls and the hydraulic fluid reservoir for the fluid. The sight glasses on the reservoir are made of glass and are brittle, so be careful when stowing items on the cat walk. There are 3 winches on the vehicle. The 2 main winches; mounted on the back of the cat walk on the left and right sides; you cant miss them, they are huge! Each one has a pulling capacity of 55-60k LBS and has 300ft of cable on each drum. The smaller winch is located on the drivers side of the cat walk frame its self. In order to operate the winches, the safety cage must be in the up right position. In the cab, the PTO switch must be in the on position (this rocker switch is located on the right side of the drivers compartment. sitting in the drivers seat, its at about the 1-2 o' clock position. the symbol on it has what looks like a gear and a half square above it). NOTE; you must have the trans mission in neutral and the brakes set in order for the PTO to engage. On the winch control box, there are 3 small switches above the winch controls. The farthest left one is the high/low idol selector switch. The center one is the High idle lock switch, and the third one is the winch speed selector. Low winch speed is MAX effort pulling power. Open the hood, engage the PTO, and hold the high idle switch in the high idle position while simultaneously switching the lock switch. you will hear the engine come up to 1,500 RPM. at this steady state idle, you can release the switches. on ether out ward facing side of the winch control back, at the very top, is a switch that controls the winch brakes. for panning out the winch cable, release the winch brakes, and select free spool. if manually panning out the winches, its much easier on the personnel who is pulling the winch cable if the winch operator puts that winch in fast speed and lifts up on the winch control lever, using the winch power to unspool the cable. NOTE: do NOT leave any less than 5 spools of cable on the drum. When the winching operation is completed, pan out the amount of cable used, re-engage the winch brake, and pan the cable back in, with some sort of resistance. NOTE: during high idle operation, if the accelerator is pressed, it will automatically go back to low idle. You open the hood during high idle to allow passive cooling of the engine to help prevent over heating and engine oil viscosity degeneration. Now that I have covered the major operating instructions of the M1070, I'll now be going in to issues that have come up, what we have done to fix them, and other modifications for power, fuel economy, and crew comfort/ease of operation.
 
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NDT

Well-known member
Steel Soldiers Supporter
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Camp Wood/LC, TX
How do you deal with the huge blind spot on the right of the truck? Soldier B hanging out the window looking for you?
 

HETvet

Member
395
6
18
Location
Bedford, texas
Maintnace and modifications

These 2 items are highly recommended to get when it comes to maintenance and modifications. But, be for warned that they can be very difficult to get, and possibly expensive. But they are an absolute life saver for the M1070 owner. First is the proper DDEC reader/computer straight from Detroit diesel WITH ALL of the unlock keys and codes. The reader shouldn't be to difficult to get, but you might have to cut threw red tape and jump threw hoops in order to get the keys and codes. Second thing is the expanded wiring diagram.

Back when the 92 series was an over the road power plant, it was a common though that "if its not leaking, something's wrong!" The fact is this couldn't be farther from the truth. The only oil that should drip is a very slight drip from the slobber tubes, the tubes for the Crank Case Ventilation system, or CCV. And in most cases, a properly running engine shouldn't even have drips from there. We have found that using full synthetic engine oil, transmission fluid, hub and differential lubricants by far out perform regular lubricants.

Starting at the air intake, good filtration of the air is key to making good power and protecting the turbo. Its highly advisable to thoroughly blow out the air filter, from the inside out using a compressed air source other than the truck, after every trip, or at every rest stop. The higher pressure the air, the better. This will also cut down on the amount of money spent on replacing air filters. Be sure to keep the air filter box seal free from rolls, rips and tears. This item will compress permanently over time so it should be replaced in order to keep a good seal. NOTE: when tightening down the bolts on the filter, DO NOT OVER TIGHTEN! Its extremely easy to brake the studs off, and the only way to replace them it to get a new air box. There is an up date service kit that includes a closure ring with 4 hand nobs and only needs 4 of the studs to close/seal properly. If you come across this item, GET IT! You can thank me later. It's also a good practice to blow out and clean the air box assembly on occasion. The vortices it creates from the "air scoop" going on the air box its self stores dust and solid particles in areas the eye cant see.

On the back side of the upper air box is a flexible tube. The other end of this tube is attached to the exhaust stack. On the air box side, there is a flapper valve that doesn't create a very good seal new, and over time the return spring goes bad. Due to this, it acts like a crude Exhaust Gas Re-circulation system. Taking in solid particulate matter and soot is going to damage turbo seals, sand blast the inducer wheel blades, and continues through the internals of the motor. We have found that by deleting or bypassing this, it cuts down on over all maintenance issues by 60%. First remove the hose clamps on the tube connected to the air box, and the connector that is connected to the air box. Pull the tube off the collector and the collector off the air box. Remove and discard the cotter pin, return spring and flapper from the air box. what's left is the 2 ears that held the cotter pin. You can break these off. I at this point sand what's left smooth, but not necessary. I've used JB weld putty and a piece of duct tape. Cover the hole in the air box with a piece of duct tap, but don't overly cover it. The duct tape is just there as a backing piece for the putty. completely cover the hole and the duct tape with the putty, ensuring you spread it out trying to get as much contact with the air box as possible. After curing, you can now sand the putty smooth if you like, again not necessary. You can leave the parts removed off, or re-install them for a stock looking appearance. If you decide to do the latter, I would recommend covering the hole in the coupler that goes in side the tube. I use duct tape and aluminized tape to not only seal the opening, but to act as a thermal barrier. The next step is to block and seal the exhaust side of the tube. Getting on the cat walk, you will see hose attached to the bottom to mid portion of the exhaust stack. Remove the hose clamp, and cover the opening on the exhaust pipe. Again, I first use aluminized tape, then Duct tape, and one more layer of aluminized tape; re-assemble.

The turbo intake tube, also called the turbo mouth piece, is attached to the air box and the turbo with T-bolt clamps. Under heavy loads we have experienced blow offs of ether end of this tube. This has been researched and studied and fond that the cause of this situation is a combination of engine vibrations and harmonics, and jarring/road vibrations. Causing the bolt to back off. We replaced these clamps with wider, stronger clamps that have locking threads on the bolt and eliminated this situation. It's suggested you do the same.

The drivers side exhaust manifold gasket for some reason is prone to leaking at the first exhaust port (farthest port forward/closest to the front of the vehicle). Red River Army Depot, Oshkosh defense, or Detroit Diesel have no known fix for this besides replacing the gasket.

The turbocharger is a Borg Warner unit from what I recall. Its got a .80 A/R, and is rebuild-able. Common failure is the inducer wheel blades leading edges being "dulled" by solid particulates being ingested. See above statements about good filtration to remedy this condition. Another common failure is the turbo seal going bad, allowing engine oil to leak past it and in worst cases, causing a runaway. The only known fix for this is to rebuild the charger with the upgraded center section; a ball bearing unit. This part DOES NOT have a NSN or part number through the TAMMS or any other ordering system through the DOD. But it can be purchased through Detroit Diesel, Borg Warner, or marine engine service and repair retailers. It is also through these outlets that you can get the rest of the hardware and replacement parts for the turbo rebuild. This engine is also equipped with a roots style supercharger. The only common issue the failure of the drive-shaft. This supercharger is not belt driven like most applications. Rather, its shaft driven from the camshaft. The drive shaft has about the same diameter as a standard No. 2 pencil. The only known cure for this is to replace when failure occurs. The symptoms for a shaft failure is low power out put and thick black smoke out of the exhaust under any load, and it doesn't clear up.

The above stated problems are the only most common issues in the drive train. There are other problems that do arise, but I cant possibly cover them all. There is an army wide though that the HET is the biggest POS in the army's inventory. This reputation is caused by operators that don't take care of their assigned vehicles. I'll admit that its a huge task to stay on top of preventive maintenance, and having a close attention to detail on all the systems and services. For example, there are a lot of lubrication points on this vehicle. And unfortunately, 75% of all HET operators will over look them due to pure laziness and no motivation. But ALL of these lube points need to be greased at least every 3 months. And as the proud owner of a FMV HET, lubing these points and replacing ball joint seals and other seals and bushings will save the owner tremendous amounts of money in the long run.

The dog house, what basically is the equivalent of a civilian center console on steroids, houses virtually all the solenoids and circuit breakers. The breakers are all on the drivers side, and the reset buttons are labeled with a data plate in the corresponding location of that breaker. The little white buttons, when pressed, will re-set the breaker if that white button is extended. The top of the dog house is removable to gain access to the breakers them self and the solenoids. The top of the dog house comes off in 2 pieces. Being made of flimsy sheet steel, more likely aluminum, can bed and flex easily if you lean on it, or if heavy objects are placed on it while driven; think radio mount, 2 radios and applicable equipment for communications. If this bends to much, witch isn't much to begin with, it can and will short out the solenoids under it; the most common one being the starter solenoid. In Iraq, we replaced the cover with diamond plate aluminum. This material is significantly stronger, easily cut and machined for a perfect and totally custom fit, and easily drilled to be secured in the factory location using factory hardware. Another advantage is a 1 piece design and personal placement of equipment for easy use. I would recommend the owner do the same of something similar.

The M1070P1 (up armored), is equipped with a very effective A/C system. Yes its a huge pain the butt to completely install. But in the heat of Texas, Iraq, and Afghanistan is a huge life saver and combat multiplier for the troops. If one chooses to install this, please be aware that its going to almost completely take away the storage ability of the bottom part of the dog house, and is going to require ether a new dog house door or cutting of the dog house door for the rear vents. But, this system is extremely efficient. Example; when I have passengers, I ensure I leave a heavy blanket or sleeping bag for them to use, it WILL give rear seat passengers frost bite on their knees from prolonged exposure. In the July heat of Iraq, running heavily loaded for more than 6 hours straight, my rear seat passengers could see their breath and were shivering. The rear vents have a sort of tray that guides the A/C air in to the vents. It has a slight down ward angle and gradually narrows as it gets to the fan/discharge. Its common practice to place drinks in the tray (as long as they aren't small enough to roll in to the fan. standard side soda cans and above are ok) to keep drinks cold. We also place the rest of the drinks (24 pack of soda and things of that dimensions) in the dog house its self to keep them cool as well. a word of caution though, don't reach to far in to the vent while the fan/A/C is on, the fan will slice up your fingers with out a problem.

The advantage of having the DDEC computer is that it can tell you any faults or issues that are present, but not sever enough to cause and warnings or check lights to come on. Things such as low voltage from the charging system, low engine oil level, high or low boost pressures, exc. Also, depending upon what version of the system the truck has, it can also give you fuel mileage data and other interesting information.

There is a lot of electrical wiring and systems. Thus it makes life so much easier when trying to trouble shoot electrical issues if you have an expanded wiring diagram.

If there ever comes a time to pull the motor, take that time to track down any electrical issues and air/fluid leaks that weren't noticeable while the motor is in the truck, or weren't accessible with the motor in the truck. also take this time to delete any electrical and fluid passages/systems that are not needed. This motor was used in various other pieces of equipment and thus were all made with the systems in place so any engine can go in to any other vehicle that used the 8V92 motor. I personally experienced in Iraq when the motor of my truck needed to be pulled for other issues. after doing what is stated with in this paragraph, the motor ran 90% better, smoother, more fuel efficient, and with more power than before.

If the time ever comes, and I hope not, the block is sleeved and each sleeve can be replaced. The same holds true for scheduled over hauls.

Next I will cover deeper in to modifications for power, economy and crew comfort/user ease.
 
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