Airpack rebuild (add pics-4/09)

[Stretch44875]

Finally got around to looking at the airpack. The pedal would stick going down, then let loose, causing some serious braking. Opened up the airpack, and the air side was half full of brake fluid. Guess I didn't need to lube the airpack after all! Looks like the pushrod seal was leaking.

Thanks to the great info here, and a kit off of ebay, rebuilding wasn't much trouble. Going to switch to DOT 3 while I am at it. Hopefully I put it back together right, didn't have any spare parts at least.

Well off to the store for a sprayer, going to build a pressure bleeder(thanks R4X4).

Dennis

 

[Recovry4x4]

RE: Airpack rebuild

Had the exact same problem with the airpack on the tractor. Rebuild took care of it right quick.

 

[cranetruck]

Re: Airpack rebuild

...... Hopefully I put it back together right, didn't have any spare parts at least.
Dennis

One important thing to remember is to install the U-cup seals with the "cup" facing the higher pressure.
DOT 3 has been good to me for a decade at least.

 

[Ferroequinologist]

RE: Re: Airpack rebuild

How does one 'convert' to DOT 3? I think I read something about it being bad for the seals and such? Or is it as simple as flush and fill?

 

[jasonjc]

RE: Re: Airpack rebuild

 

[vbrescueman]

RE: Re: Airpack rebuild

I've rebuilt my airpack in the past...gonna do it again soon and post some pics. losing fluid in the system... airpack or master cyl? I believe a flush -n- fill w/ cleaner and air pressure will work. Will it get all fluid out of brake cyl or take lines loose at cyl and flush? TIA Ya'll
Doc

 

[Stretch44875]

RE: Re: Airpack rebuild

Well, I am using air to blow the lines clear. Takes a while to get most of it. Figure to pump some DOT 3 through it and call it good.

Sure cranetruck, now you tell me what way the seals go. No problem, the TM is pretty clear, and had my share of rebuilding cylinders and such.

Pics? to late now...

 

[Stretch44875]

RE: Re: Airpack rebuild

Success! After running about a gallon through the braking system, I have brakes. I think the pedal is a bit lower now, hard to tell because the brakes push easier. Pushing hard on the brakes puts the pedal about 1/2 down, and will skid the rear tires.

Dennis

 

[vbrescueman]

RE: Re: Airpack rebuild

Hey Stretch...did u disco the brake lines @ cyl or just push fluid out the bleeder ports? gonna do the same to my deuce but I've read that dot5 and dot3 make a mess if left together in the sys.
Doc

 

[Stretch44875]

RE: Re: Airpack rebuild

I can be hillbilly at times, I hooked an airline to the master cylinder and blew them out one bleeder port at a time, until no more fog. When I was filling the system with Dot 3, the fluid coming out was cloudy at first, then ran clear. Ran the truck around for a while and bleed a little more, clear brake fluid came out.

Dennis

 

[vbrescueman]

RE: Re: Airpack rebuild

works for me! I was planning on hooking up the air and doing the same thing... just was wondering about the wheel cyl and air pack. Thanks,
Doc

 

[gimpyrobb]

So I took apart two airpacks to rebuild this weekend. Both had some wax build up in the air piston can. I am guessing this is not supposed to be there? What causes it?

 

[Stretch44875]

Just old grease from where it was rebuilt/built. Proabaly vasoline for the seals.

 

[Boatcarpenter]

Here is something I found and saved when I was rebuilding my airpack. Take heed of the possibility that the directions that you followed may be incorrect. The incorrect info happens to be in TM 9-2320-209-34-2-1 as per attachment.
BC

 

[gringeltaube]

Dito on this!

Although, with a little common sense... there is only one way!

This is what the book should tell...

G.

 

[tjcouch]

I am replacing my airpack tomorrow . . . . I assume all of the fluid will drain out of my MC (and remote reservoir) during this process? (Unless I take some steps to prevent it . . . )

 

[saquishmike]

what are used airpack worth?

 

[Floridianson]

Just a thought but when I do my system fluid change I will use the sprayer first with just air or use compressed air and discharge all old fluid first then re hook up sprayer with BF then feed and bleed.

 

[Stretch44875]

Some pics from a recent rebuild. Was rebuilding one, and needed some parts so I grabbed the spare airpack. Check out the bore, a little rusty.

Dennis

 

[gimpyrobb]

I would like to add, there is an article somewhere that details rebuilding one of these. Another member was kind enough to warn me, the end studs(as seen in the 2nd pic above) will break off if you are not carefull putting it back together. The article says to torque to 30lbs. Please be carefull when you are putting it back together, those studs are not on there that great.