New Airpak Question

[bguy193]

When installing a new airpak do you just add a little oil, bleed the system, and you are good to go or is there another step in there? Also, how much oil should you add to a new airpak?
As always....... any help is much appreciated.

 

[gimpyrobb]

You might get away with that, but I think you would be better off bleeding the whole system.

 

[DieselBob]

I would agree that a complete bleed of the brake system would be far better. I just don't see taking any chances with the brakes.

 

[flyxpl]

Brian ,I have a military power bleeder . You are welcome to stop by and barrow it if you need it .

 

[bguy193]

Sorry I wasn't more specific , I don't like to take chances with brakes either..... I noticed the airpak going bad before I got started on the wheel cylinders so I'm gonna have to bleed the whole system anyway. I just didn't know how much oil I should initially add to the airpak, and if there were any hidden procedures for setting up a new unit. While I'm doing the airpak I figured it is a good time to do the MC as well. So when I'm done I'll have an almost new braking system.
Also for anyone stopping by to read this........ Although your wheel cylinders look fine and work fine, be sure to peel back the boot a little and look inside to inspect what you can't see you might be supprised. one of mine had some gunk and a little fluid in there. You should also wear safety glasses while doing so because there might be a little preassure in there that will spray some fluid out at you ( This happened to me).

 

[bguy193]

Brian ,I have a military power bleeder . You are welcome to stop by and barrow it if you need it .

Thanks Joe, But I already built one out of a garden sprayer about a year ago.
I'll still stop by and check it out though.

 

[rlwm211]

The airpack should be well lubed if it is new. I would squirt a good amount of airtool oil up inside the air line that supplies air to the air pack. That way the oil will pass through all the parts in the air pack.


I have heard of adding oil to the piston area of the air pack. I believe that this may be in a couple of publications as well. I rebuild the old style airpacks and I believe that there is a tendency to put too much oil inside the piston and that can be very problematic. After considering this for a while, I have come to the conclusion that the oil should be administered in the air line as 9 times out of 10 it is the airvalve that fails in some way or another and causes the airpack to fail.

The other prime reason for airpack failure is when all the brake fluid leaks out and moisture gets in the system and corrodes the compensator bore and the slave cylinder bores of the airpack assembly. This usually is found on a truck that has been sitting for a long time such as when they come out of GL or if you are recovering a truck that has been set in the weeds for many years.

I applaud your efforts in making your braking system safer by replacing all the wheel cylinders. I am just adding my two cents to this and understand that others will agree or disagree.

Best of luck

RL

 

[motorolanut]

You might get away with that, but I think you would be better off bleeding the whole system.

Nice Avatar!

 

[flyxpl]

Thanks Joe, But I already built one out of a garden sprayer about a year ago.
I'll still stop by and check it out though.

I have the weed sprayer unit too . I actually have yet to use the military bleeder since I got it . I was going to let you be the first one to get it dirty . You really can't beat the homemade bleeders . You will have to stop by when we get some snow , I think that will be the best time to play with the 548 .

 

[crazywelder72]

i just rebuilt my airpack and went right by the TM (and i have the proper seals in the right place on the confusing part). I am having trouble getting a good pedal and i am still bleeding. I didnt recall seeing anything about "priming" the air pack with oil or fluid.

Am I missing something?

 

[doghead]

Powerbleeder?

If not,wait a day and see if it feels better.

Are your brake shoes all adjusted correctly?

 

[crazywelder72]

Hey DH, Thanks for chiming in.

Just after I posted this I tried to have the pressure bleeder pressured up and pumped the brake pedal at the same time.

I was able to get full pedal. I released the pressure from the tank and the pedal was solid. Seems like that got me over the hump.

 

[cattlerepairman]

Hey DH, Thanks for chiming in.

Just after I posted this I tried to have the pressure bleeder pressured up and pumped the brake pedal at the same time.

I was able to get full pedal. I released the pressure from the tank and the pedal was solid. Seems like that got me over the hump.

My understanding is that touching the brake pedal while the power bleeder is connected is a big no-no and you risk MC or air pack issues if you do that. Perhaps that is only true if there is air pressure in the truck air tanks.

 

[crazywelder72]

interesting. There was air in the tanks when i did it. I guess I'll just have to keep an eye on things.