How in the world do i service my air pack??

[BimmerPower]

Well unfortunately im only able to use the internet via my phone where im currently at and am having trouble searching for the appropriate info regarding flushing or servicing the air pack on my truck. My brakes are acting up so I introduced some alcohol via the compressor and flushed out about a cup of crud from the air tanks. My issue is that my brakes work fine after one or two pumps but then are non existant after that. What boggles my mind is that when the brakes seem to work fine, I don't hear air being expellent from the brakes after releasing it (kind of like a blow off valve), but when they are not working, I can clearly hear it. My question is where can I find a tm or literature on servicing my air pack? I believe I have the old style but am not sure. I hope I can get some help and I did in fact try to search numerous times but have come across nothing. I have also included a picture of my airpack. Thanks!

 

[Heavysteven]

There is a j pipe on the air pack you can remove it and squirt air tool oil in it or if your lucky remove the pipe plug on the back. FYI mine is striped out

I would bleed the brakes and do a inspection.

 

[rlwm211]

From the sounds of things, your compensator valve is sticking and not increasing pressure on demand. You can shoot some oil in the J pipe, vut that only lubes the piston and exhaust valve and that is not where the problem is. I would put a small amount of oil in the air inlet line to the air pack, build air and then cycle the air pack. A small amount is less than a teaspoon full. I use an eye dropperful or two. I would remove the bottom two bolts that hold the air pack and you should be able to remove the inlet air line and squirt some oil into the line. Do this carefully as you are moving brake and air lines to do it. Re install the bolts and give it a try.

There are comprehensive rebuilding instructions in one of the TM's but since the Old Steel Soldiers site is gone, I am not sure how you would get it.

You can buy a new or rebuilt airpack as well. The kits are on Ebay and in the classifieds here sometimes.

The other issue is which airpack you have. The older style has a piston cannister that is at least 10 inches long and the end has six bolts and sets inside the end of the cannister. The new style has an elongated BOSS casting that extends the end of the air pack to the mounting bracket. Old style air pack kits are available. New Style are not as far as I know.

Try lubing the inlet air line to the air pack and post how you make out. I am sure we can get you through this...

RL

 

[Heavysteven]

can you lube the inlet from any other point in the system?

 

[rlwm211]

I am sure you can, although it would infiltrate the whole system and really not get to what you want it to.

I have found it is pretty easy to swing the airpack away from the frame just enough to take the air line that is the inlet off, and then squirt some oil in the line and then reconnect it. The other end at the tank is much more difficult to get to.

RL

 

[Heavysteven]

Thanks, for the info very informative. Looking forward to do this procedure in my truck.

 

[rlwm211]

Remember a little air tool oil goes a long way and too much just accumulates dirt and gunk.

RL

 

[SoldierwithaM109A3]

I need to understand what line and where on the air pack i put this oil does anyone have picture they could show and what to look for ? thank you

 

[rlwm211]

If you look up at the air pack, the air line that pressurizes the air pack comes from the back and attaches on the frame rail side of the valve assembly that is ahead of the air piston. This line has no other connections and is likely to be a straight fitting into a 90 degree fitting on the side on the end of the air valve assembly on the air pack. This is closest to the frame. As I said, it goes straight back along the frame to the air tank.

The other air line connections on the frame rail side include the slave air connector for the trailer on what would be the "front" of the air valve, an exhaust line that heads up and towards the air cleaner area from an angle fitting that is closest to the main body of the assembly, and the J-Tube which connects the air valve to the back of the air piston assembly.

I have rebuilt many of these and the common problem is gunk getting into to the actuator for the air which can get siezed up and you are left with only the braking you can create with your foot on the master cylinder. Another common issue is that a leak occurs and as the brake fluid leaks out moisture gets into the system and migrates down from the master cylinder into the air hydraulic unit specifically into the compensatory valve. This causes rusting and deterioration of the bore that this valve is in along with the main bore of the slave cylinder.

For information, the master cylinder creates about 500 PSI of pressure, and the air hydraulic boosts this to upwards of 2000 PSI. When the air hydraulic booster is off line, you have very little braking and operating a truck this big without adequate braking is extremely dangerous.

If you can get your hands of them, the following TM's are helpful

T M 9 - 2 3 2 0 - 2 0 9 - 2 0 - 3 - 2

Contains the R and R instructions and indentifies the connections to the unit.

TM 9-2320-209-34-2-1

Contains the rebuilding instructions for the airpack assembly.

I know that the Old Steel Soldiers site is down so you will have to be resourceful in locating these two TM's.

RL

 

[BimmerPower]

Thanks for all the replies. I look forward to trying out this procedure before looking at rebuilding my unit. Would you be able to let me know if I have an old or new style air pack

edit: I have also come across these two images during my search. Maybe they can be of use?

 

[rlwm211]

old style

The airpack in the picture is an old style. Kits are commonly available to rebuild them. The diagram is for the same model.

The PS Magazine article shows the usual method of lubricating an air pack. That cannot hurt, but to be honest your problem is ahead of that in the air system.

When you rebuild an air pack, you lubricate all air system parts with air tool oil before assembly. This includes the piston assembly and cylinder, as well as the air valve and the bore it resides in. There is also an air release valve. Lubricating the air side of the air pack at the Inlet, while more difficult to do, is going to get lubircant to all of the air system parts. Adding lube in the rear of the piston will only lube the piston assembly and the exhaust valve.

What will be telling is if the behavior of your air pack changes after you do this. If it does then you have found a potential problem and dealt with it. If it remains the same then you are faced with a completel rebuild at some point.

The reality is that most of these trucks have sat for years. They started phasing them out of active service many years ago and they have been removing them from the NAT Guard over the last few years. If a truck had an issue they parked it. Now when it comes time to run them to a depot to auction them off, the deferred maintainence and the lack of use starts rearing its ugly head.

My truck was one of those "motor pool queens" that sat for at least three years before being sold at auction. It had a brake issue and had a leak which resulted in moisture getting in the brake master and the booster. I ended up rebuilding the air pack, replacing the master and all the wheel cylinders. Hopefully yours will only require some pm and it will be good to go.

Keep us posted.

RL

 

[dabtl]

I change all my plugs to hex pipe plugs to use hex wrenches for removal. The square head plugs are difficult to remove when painted and such.

 

[BimmerPower]

It looks as if I'm going to have to rebuild my air pack and master cylinder in order for a complete brake system. I don't know if I'm capable of doing that though! I can't even remove the oil fill pipe plug on the air pack to add a bit of oil!! Is there anyone or place that will rebuild these for a price, or send me a rebuild one for my core (same with my master cylinder)?

 

[Gunnar1071]

It looks as if I'm going to have to rebuild my air pack and master cylinder in order for a complete brake system. I don't know if I'm capable of doing that though! I can't even remove the oil fill pipe plug on the air pack to add a bit of oil!! Is there anyone or place that will rebuild these for a price, or send me a rebuild one for my core (same with my master cylinder)?

Dueceman surplus has the master cylinder on page 2 of his list.

Parts

 

[dabtl]

It looks as if I'm going to have to rebuild my air pack and master cylinder in order for a complete brake system. I don't know if I'm capable of doing that though! I can't even remove the oil fill pipe plug on the air pack to add a bit of oil!! Is there anyone or place that will rebuild these for a price, or send me a rebuild one for my core (same with my master cylinder)?

They are easy enough to rebuild. Get a brake cylinder hone for the small piston area and use emery cloth for the big air cylinder if necessary. Follow the TM and pay special attention to cranetruck's thread on this.

Rebuild kits are readily available. Change the rear square plug to a hex plug while you are at it.

 

[sandcobra164]

I've been reading through airpack oiling threads. I got a chance to meet Phil2978 again today as he was picking up some Deuces out of Albany, GA. He was hooking up a line to activate the brakes on one of his new trucks behind his M109 that he drove up there. He showed me just how simple it is to lube the airpack and goodness what a difference it makes. On the old style, undo the J pipe at both ends and lube both sides of the airpack with proper oil, re-assemble, build air and start pumping the brakes. My truck used to have lackluster brakes and a very hard pedal. Now it stops without a little more effort than my car and can lock the wheels down without much more effort than that. It's certainly on my annual maint. list now. Also, before, my truck wouldn't make any whooshing sound at all from the airpack but you can easily hear it now. Those who haven't done it, get out there and do it!!!! Thanks Phil!!!!

 

[M35A2-AZ]

I am looking at oiling my Air pack and I see the plug at the back and the j pipe at the back, but I do not know which j pipe is on the front?
Is that the only places to oil it?

 

[Floridianson]

You can remove the tool box and lube then in comming line if you want to take the time. Air tools then it's a 15 min job. Wonder if you could add a fitting and a line up to better access and have a cap on that. Easy to lube whole airpack then?

Yes AZ that gets it to the airpack it's self and the out going valve. If we could get it in the incomming line we would catch the incomming valve to.

 

[rlwm211]

I prefer to lube mine on the inlet of the air going in.

A little oil goes a LOOONNNGGGG WWWWAAAYYY so
use it sparingly.

Better to lube it a couple of times a year than to flood the air pack with too much.

I have revuilt air packs where I poured the oil out as there was too much inside.

One, maybe two squirts of a pump oil can is enough.

Hope this is helpful.

RL​

 

[stancanpara]

This is as close a thread that I can find on my problem which is actually opposite of this problem. I pump the brakes up and sometimes they are fine, but over time the brake pressure seems to build and build until the brakes pretty much lock up... I bleed a brake and it is fine again for a while but it will inevitably build up again... I have completely flushed the system and replaced with new silicone, I have replaced the master cylinder and air pack (with take offs) and it persists... I'm clueless.... Is there some kind of check valve some where in the system? I can't seem to find any literature reflecting this in the TMs... Perhaps I'm just blind and missing it somewhere.....?