M923A2 Issues

[BrianM2004]

Ok guys, Long time member/lurker finally posting instead of reading.

As of last week I purchased 5 M923A2 5 ton trucks from Ft Huachuca here in Arizona where I am currently stationed. I am not a mechanic by any means and my motor pool has already shipped to Ft Hood with 11th Sigs advanced movement team. I do have a mechanic from 111th MI that can look at the trucks but not until Friday. Problem is all the trucks must be removed by friday. Here is the low down, All 5 trucks required new batteries so we swapped the 4 battery system for dual Napa 7271 batteries in all the trucks already. After installing batteries 3 of the trucks start and run nicely, 1 we drove off the lot on Friday the other two are perplexing. Lets call the dually with locked brakes truck 1: Truck 1 has its rear brakes locked, it is odd because it pulled off the line just fine and I parked it away from the other trucks while we worked on battery swapping and when it was restarted to move it off base the rear wheels were locked up. I must admit this may be my fault as I assumed the brake system was lubed which it may not have been needless to say it locked up and will not unlock. I know I can cage the rear and drive it off using front brakes "9 mile ride home open desert roads and flat terrain 4 turns total" but I dont know how caging is done... Any help?

Truck 2: Started and ran fine, pulled off the line. Backed it up to another truck with starting issues and hooked up a borrowed tow bar to tow it out. After readying the trucks for towing tried to put the truck in gear and pull forward with no luck. Truck revs in reverse, revs up in neutral but does not rev up beyond idle now in forward gears motor just idles as if it were still in neutral when peddle is pressed to give it gas.

Trucks 3/4: Both turn over easily and sound normal, but will not start as if fuel is not making the cylinder. I very brief shot of ether while the engine is turning results in a very clean and effective start of the motor then it dies when the ether dissipates. This was only done once to prevent ether dependency. We tried priming the motor with the primer inside the engine bay to no avail. Any ideas. I would like to get some of them removed if possible prior to friday, I could call in a favor with the DOL and ask for a removal extension but I just want to get them off post ASAP. My mechanic cant answer these questions until Thursday night as he is currently at WLC till then. Any ideas guys? Also, I searched out and found a few related topics on here but nothing exactly matching other than break caging but the info was not broken down enough for a complete no nothing to understand as far as break caging. Thanks all

 

[smoke]

Check the fuel shut off solenoid on the injection pump make sure it moves the lever it is attached too. If it does not move lever no fuel condition. You can take lever off and zip tie it up and bypass the solenoid. That if they are a2.

 

[Reckless]

Check the fuel shut off solenoid on the injection pump make sure it moves the lever it is attached too. If it does not move lever no fuel condition. You can take lever off and zip tie it up and bypass the solenoid. That if they are a2.

On the same note, check the emergency shutoff lever. My in cab lever was all the way in but the spring was shot (under the hood) and the pump lever never moved back to the right position causing it to not start.

 

[BrianM2004]

Well, we moved 2 more trucks today. The brakes were easy to cage, and the one that wouldnt rev up for some odd reason fixed itself. Low and behold the final 2 were empty of fuel though still having issues getting fuel to cycle through the motors even when priming the motor. Thanks for the help so far guys.

 

[BrianM2004]

Update:

Truck number 1 has an issue where sometimes when put into gear it drives just fine and others it will just rev and not budge an inch. When it does engage it drives perfectly with no issues or noises. When it it first started it will either work fine, or not drive at all... Any ideas?

Truck number 2: Brakes are fully caged, yet they still are engaging and sticking causeing the brakes to either heat when driving which you can smell but just slightly or to fully lock if it was put into a complete stop. The only way to loosen them is to put it in reverse and force it back about 30 feet at which time they loosen to the point where they are engaged but lightly. Any ideas?

Trucks 3/4 both have brand new napa batteries, and fresh diesel. Both trucks turn over as they should and sound strong, air filters are clean, fuel lines are free of air and filters are new. Glow plugs are heating as a small shot of ether turns the motor over. So in short, we have air, power and a strong starter yet the darned thing just try to turn over yet never catch and wont start. If the motor cut off was the cause then the motor wouldnt try to start at all but they both do. Only thing I can think of is a blockage in the injectors but what are the odds both trucks have zero injectors working? I have a heavy diesel mechanic here on base that works in our motor pool but he is at WLC for another week. Any ideas guys? I have one truck that runs great, the others are a complete WHISKEY TANGO FOXTROT. Sidenote, We did pressurize the fuel tank to 15PSI to try and force fuel to the motor if the lines were airlocked while cranking and still a no go on a start. We know for a fact the lines are clear atleast to the primer pump and free of air. all seals are new with no air seeping in.

 

[BrianM2004]

Found this quote on another thread, Does anyone have a picture of this solenoid? This makes sense as to what the issue may be, we have power, hot plugs and air but if the fuel shutoff is engaged it would account for no start!

If it's a Barstow truck, I can almost ensure you that there are no petroleum based fluids or batteries in them. I'd advise against towing as the diff's and transfer will be drained as well. As far as M939A2 quirks, I've had trouble with fuel shut off solenoids. They do a great job shutting the motor down, they just don't retract when you go to start. I've had many a truck driver tell me his truck will turn over but not start. Open the hood, go to the driver's side by the injection pump, push the solenoid in by hand, rotate the throttle linkage (counter clockwise?), release solenoid and fires off pretty quickly.

 

[Vintage iron]

truck #2 check the yellow glad hand cap on the front of the truck it should have a vent on it.

 

[Suprman]

Maybe bad seals in the primer pump I believe they can be replaced with generic o rings. Did you drain the fuel water separator it's a cock on the bottom of the filter? Could the fuel filter be clogged? I believe there is a catch screen somewhere along the way too. Can you peek into the tank I have heard of the fuel intake tube coming apart?

 

[BrianM2004]

Now that the site is back up I can update, All the trucks are running great. Turns out someone at GL had pulled the emergency engine stop and never reset the actual arm under the hood. As soon as I reset it they fired right up. The truck with the braking issue seemed to be related actually to the caging. I uncaged the brakes in the rear and they suddenly worked just fine but caged they actually engage???? Never heard of that before. The truck with what I thought was tranny problems turns out the rear wheels lock so bad it just wont let the **** thing move. Will be caging those brakes tomorrow and checking to see if that fixes the issue.

Thanks for all the help guys, This site probably saved me thousands in unneeded mechanic bills!

 

[BrianM2004]

truck #2 check the yellow glad hand cap on the front of the truck it should have a vent on it.

Do you have a picture of this? When I find it what are you saying I should do with it? Im a bit confused. I found another thread on the forum here mentioning this as well but no real description of what a glad hand is or what a service side is. But the description of the issue is spot on. when it is first started it runs fine, but the more you drive it and use the breaks it begins to tighten and lock up the rear. They said something on the other thread about needing to remove the glad hand cover or opening a vent. If I can get a picture of this or clarity on what I am supposed to do with it I would GREATLY appreciate it. All other issues have been solved so it would be nice to fix the last remaining one.

Thanks

EDIT:

Ok, I figured out what the heck the glad hands are. How would they affect the brakes if I dont have airlines hooked to them such as when towing? How could they build pressure? If this is the cause, how do I stop the building of pressure?

 

[Rolling Thunder]

M923A2 rear brakes locked up

Just bought M9232A2 and same issue has occured with my rear brakes all four of them. How do you cage or un-cage the brakes? Did this resolve you issue with the brakes, mine problems are exactly what you describe. Help, please.

 

[RustyM923]

Just bought M9232A2 and same issue has occured with my rear brakes all four of them. How do you cage or un-cage the brakes? Did this resolve you issue with the brakes, mine problems are exactly what you describe. Help, please.

I found this in the TM:

https://www.youtube.com/watch?v=BSqQTKs6v2A

 

[wreckerman893]

What kind of MV addicted fool buys 5 trucks at a time? Errrrrr.........wait........never mind.

 

[Rolling Thunder]

Lets just say a nut. I caged the brakes and still stalls when i put in gear and now the reverse has decided to work when it wants to. This is all on same truck.

 

[Rolling Thunder]

Thank you the video was perfect. Its building great pressure but dont know if the right pressure is getting to the rear brakes. Seems all four siezed and wont release....suggestions would be wonderful. The model is MY Division of Harsco M923A2 5-Ton Cargo Truck w/ a 14-Foot Dropside Cargo Body.

 

[porkysplace]

Thank you the video was perfect. Its building great pressure but dont know if the right pressure is getting to the rear brakes. Seems all four siezed and wont release....suggestions would be wonderful. The model is MY Division of Harsco M923A2 5-Ton Cargo Truck w/ a 14-Foot Dropside Cargo Body.

First off I am guessing you have no experience with air brakes , with that said you need to download the TM's ( I posted a link in your other thread ) the tm's ending in -P are parts tm's they have diagrams of the parts . It sounds like the brakes are rusted to the drum from sitting . Backing off the adjustment and hitting the drums with a hammer will sometimes free them up , this will require taking the tires off . But it is dangerous to start turning wenches on air brakes without basic knowledge of how they work which is why I recommend downloading and reading the TM's.

 

[Rolling Thunder]

It is limited, very limited. I have a m35a2 but never had any issues with brakes or anything major as for as that goes. the 5 ton is new to me but i do like and will put the time in to make it work. Have read the TM i have downloaded but dont seem to have the in depth ones everyone else speaks of, especially for trouble shooting versions. The ones i have read are basic and dont offer much in way of trouble shooting and or narrowing down issues in a step process. Maybe the dont exist and i dont know where to look. But im hard headed and hard working and have decent set of skilled hands. Thank you for the TM's the wiring diagram opened up just fine but having trouble loading the others and unzipping them. You help is appreciated and please dont doubt my time in the tm manuals i have been reading till im cross eyed trying to figure this out. Cant be this darn hard to fix. Yea the second thread was a mistake when i was trying to figure out how to create on period on the issue.

 

[porkysplace]

It is limited, very limited. I have a m35a2 but never had any issues with brakes or anything major as for as that goes. the 5 ton is new to me but i do like and will put the time in to make it work. Have read the TM i have downloaded but dont seem to have the in depth ones everyone else speaks of, especially for trouble shooting versions. The ones i have read are basic and dont offer much in way of trouble shooting and or narrowing down issues in a step process. Maybe the dont exist and i dont know where to look. But im hard headed and hard working and have decent set of skilled hands. Thank you for the TM's the wiring diagram opened up just fine but having trouble loading the others and unzipping them. You help is appreciated and please dont doubt my time in the tm manuals i have been reading till im cross eyed trying to figure this out. Cant be this darn hard to fix. Yea the second thread was a mistake when i was trying to figure out how to create on period on the issue.

Somewhere in these will be brakes, I don't have these downloaded to search
TM9-2320-272-24-1.pdf a google search shows it should be this tm for the brakes.
TM9-2320-272-24-2.pdf
TM9-2320-272-24-3.pdf
TM9-2320-272-24-4.pdf

Parts tm's
TM9-2320-272-24P-1.pdf
TM9-2320-272-24P-2.pdf

 

[Rolling Thunder]

cant thank you enough for the amount help you providing for me, it is much appreciated. Will keep you updated on the progress, again thanks. I will be under it today after work, these things drive me nuts till i get em fixed.