More brake problems, what can it be?

[tjcouch]

I am befuddled to say the least.

All wheel cylinders have been replaced.

All lines have been replaced, both hard and soft.

New master cylinder a couple of years ago.

New airpack a month ago.

BUT, I once again am having the same problem - if I drive at 50 m.p.h w/o stopping on the interstate for more than 45 minutes, when I do finally exit and apply the brakes, they drag and do not release.

Opening the bleed valve on the new airpack blew out fluid, and then I was good to go.

Drove home using surfaces road w/o problems.

What else can be going wrong?

 

[gimpyrobb]

short or long airpack?

 

[ncduece]

make sure the vent on the master cly cap in not clogged

 

[tjcouch]

short or long airpack?

Not sure . . it was identical to the one I removed . . . .


20 " from the air tube to the wet side.

 

[Recovry4x4]

Mal adjusted master cylinder. Check free play underneath. If the piston in the master is not returning completely, it will block the compensating port which allows fluid to return to the reservoir. Loosen up the push rod from the pedal a bit!

 

[tjcouch]

make sure the vent on the master cly cap in not clogged

Interesting - I have a remote reservoir of fluid running into the cab like others that have posted on here repeatedly . . . could that be the cause?

 

[tjcouch]

Mal adjusted master cylinder. Check free play underneath. If the piston in the master is not returning completely, it will block the compensating port which allows fluid to return to the reservoir. Loosen up the push rod from the pedal a bit!

Ah ha! How much is "a bit"? Is this in a TM somewhere? If not more specifics would be great. (I am not much of a gear head . . . . but God knows I learn more everyday b/c of the vehicle choices I have made!)

If that fixes it I guess I will have a back up air pack that I replaced b/c I thought that was the problem!! LOL (PM me if you want a used one! LOL)

 

[dabtl]

You have the long airpack.

 

[tjcouch]

Oh never mind Recovery4x4 - I understand what you mean know . . . I had to climb under the truck and lay in an ant bed to understand. Why are these lessons always painful and sometimes poisonous.

 

[drgreg]

If it was easy, we would have the office girls do it. Oh sorry, you don't work for me.

 

[Recovry4x4]

There is a return spring on the brake pedal. If there isn't one, there needs to be. 1" of pedal free travel is what the TM says IIRC. As long as the pedal return spring is pulling the pushrod out of the piston at least 1/16th" that should give you adequate piston return. Next time it does this, crack the steel line that goes from the master to the airpack and see if it relieves the pressure. If it does, that means the problem is somewhere in the master cylinder or adjustments.

 

[dirtyfingernails]

Kenny's right as usual. I had the EXACT same problem with my deuce. Adjust the free play to 1/2 inch. Push the brake pedal with your finger until it reaches the bottom of its free play. Scribe a mark on the pedal arm inside the cab at the floor board with a piece of chalk. Release the pedal and measure the distance from the floor to your mark. If it's not free, it will trap fluid and be unable to release at the master cylinder.