M923A1 New Purchase

[Randyw]

Just purchased my first M923A1 5-Ton and have to say I am very impressed. The truck is in excellent condition and everything on the truck works great. Thanks for all the info from the guys in my original post before deciding to make the purchase. Still have to get it registered and insurance but what little I have driven it the trucks drives very well. Any input on anything I need to do to the truck please let me know. Thanks!

 

[desmodromic]

Nice score. I need one.

 

[98G]

Picture, tags inside drivers side door jamb?

 

[simp5782]

Nice score. I need one.

Great for nyc traffic to just go postal and run everyone over.

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[desmodromic]

Great for nyc traffic to just go postal and run everyone over

Exactly.

 

[Randyw]

Picture, tags inside drivers side door jamb?

https://www.dropbox.com/s/l39pol5oq6v4v2g/5-TON_tags.JPG?dl=0

98G Here are the pics of the tags in the door jam. I don't know what the tags mean but it appears on one tag the truck was overhauled on 3/04. But the MWO tags say 11/08 and 8/10. Maybe someone on here can shed some light as to what they mean.

 

[Csm Davis]

Just start changing every piece of rubber hose, fuel lines first, then belts ect.. Then filters and fluids. Look at disabling the transfer case auto engagement switch, so you can drive on pavement in low range and back up in low if you need to. If the transfer case lever is hard to shift you might want to disable or clean and repair the lockout cylinder and or solenoid.

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[Randyw]

Just start changing every piece of rubber hose, fuel lines first, then belts ect.. Then filters and fluids. Look at disabling the transfer case auto engagement switch, so you can drive on pavement in low range and back up in low if you need to. If the transfer case lever is hard to shift you might want to disable or clean and repair the lockout cylinder and or solenoid.

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I did a good check on all the hoses and belts and to my surprise they look fairly new. The belts look very good as well. The one thing I have noticed is the emergency brake alarm will sometimes stay on after releasing the break. It will either go off, stay on, or come on and off while driving. Any suggestions on how to fix that?

 

[rhurey]

I did a good check on all the hoses and belts and to my surprise they look fairly new. The belts look very good as well. The one thing I have noticed is the emergency brake alarm will sometimes stay on after releasing the break. It will either go off, stay on, or come on and off while driving. Any suggestions on how to fix that?

Check the ground. It's based on a contact switch in the handle grounding out the alarm. The connection between the switch and the floor was bad on mine.

 

[Trailboss]

... The one thing I have noticed is the emergency brake alarm will sometimes stay on after releasing the break. It will either go off, stay on, or come on and off while driving. Any suggestions on how to fix that?

That alarm is also for when the air pressure drops below about 60 psi. Check those gauges when the alarm goes off when driving. With faulty brake system valves, sometimes holding your foot on the brake will dump air pressure.

 

[Csm Davis]

You can't look at the fuel lines and tell if they are good. If you want to test instead of replace then you will need to unhook at the tank and the filter then plug one end and pressurize the line and check for leaks then do the line to the pump the same way around 40 psi should be good.

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[Csm Davis]

The small clear plastic line going to the primer pump is almost always bad also.

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[Randyw]

You can't look at the fuel lines and tell if they are good. If you want to test instead of replace then you will need to unhook at the tank and the filter then plug one end and pressurize the line and check for leaks then do the line to the pump the same way around 40 psi should be good.

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Thanks, I still plan on changing everything out even though it looks new and in good shape. Just rather be safe then sorry after getting it where I can drive it pretty regular. My next job will be changing hoses, belts, Oil and filters.

 

[Randyw]

That alarm is also for when the air pressure drops below about 60 psi. Check those gauges when the alarm goes off when driving. With faulty brake system valves, sometimes holding your foot on the brake will dump air pressure.

That was also my concern but while driving the truck I paid close attention to the gauges and the air pressure stayed above 60 pounds the entire time. Mainly stayed around 120.

 

[Csm Davis]

That was also my concern but while driving the truck I paid close attention to the gauges and the air pressure stayed above 60 pounds the entire time. Mainly stayed around 120.

You might wnt to start there and remove one valve at a time and clean and check each one through out the whole air system, many of these are full of rust and hidden problems.

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[BenRoberts]

Might think about upgrading the air dryer to the mrap style one.

 

[98G]

That was also my concern but while driving the truck I paid close attention to the gauges and the air pressure stayed above 60 pounds the entire time. Mainly stayed around 120.

Randy, do you understand the differences between a full airbrake system and passenger vehicle brakes?

In normal operation, you should never see 90psi or below. At 90psi your alarms come on.

At 70psi your secondary systems no longer recieve air (horn, wipers, transfer etc)

Below 60psi, your springbrakes are pending activation.

Also, FYI, TX requires a class B for the 939series trucks.

 

[98G]

The RRAD tag on the doorjamb indicates the truck went through reset in Red River Army Depot.

 

[Randyw]

Randy, do you understand the differences between a full airbrake system and passenger vehicle brakes?

In normal operation, you should never see 90psi or below. At 90psi your alarms come on.

At 70psi your secondary systems no longer recieve air (horn, wipers, transfer etc)

Below 60psi, your springbrakes are pending activation.

Also, FYI, TX requires a class B for the 939series trucks.

Yes I understand the breaking systems. The pressure gauge stays around 120 psi while driving that's why I was thinking the alarm buzzer was the problem. The light does not flash only the buzzer sounds. Some times it does and sometimes it does not.

 

[98G]

Yes I understand the breaking systems. The pressure gauge stays around 120 psi while driving that's why I was thinking the alarm buzzer was the problem. The light does not flash only the buzzer sounds. Some times it does and sometimes it does not.

120 is where it's set.

They're notorious for constantly and intermittently alarming for no reason.