drivers side front brake keeps locking up after master cylinder and hydro boost replacement.

[T_Murph]

I have an 04 2500 with nv5600.

I replaced my hydro booster & master cylinder.

Yes I did bench bleed the mc before installing.

Since then my driver side only caliper engages / locks up daily. If I open the bleeder screw it relives the pressure for about 24 hours. And then the issue comes back.

I shot the parts cannon at it. I've replaced the caliper, the rubber flex brake hose (oem) and the steel brake line that connects to the rubber line and runs up to that silver block next to the battery. I've also replaced the two brake lines that run off the mc to the silver box of lines next to the battery.

I don't know what to do at this point... is it something with the master cylinder?

 

[Wayne M.]

When and how did your brake problem begin?

 

[NIsaacs]

Check to see if your push rod adjustment is right. If it is too long drag will result. Here is a diagram of what I am talking about. It is a vacuum booster but it applies to hydro boost too. Some push rods are not adjustable, so you have to get a different one or possibly grind them or use spacers.

 

[sag2]

It has to be the master or pushrod. To check the pushrod vs. the master, slide the master off and put a flat washer under the mounting tabs. If that fixes it the pushrod is too long.

 

[T_Murph]

It has to be the master or pushrod. To check the pushrod vs. the master, slide the master off and put a flat washer under the mounting tabs. If that fixes it the pushrod is too long.

Thank's I'll try that.

 

[SnoKing]

Replace the caliper?

 

[NIsaacs]

Replace the caliper?

Post one said he did that, along with other parts.

 

[Bill Scott]

My 2004 did that. Problem was piston in caliper. Pistons were resin even though they have a cover that makes them look like steel. Piston would stick because it became out of round. Resin piston is resistant to heat so do not replace with steel. Piston gets just a little sticky but clears when you crack brake line and cause bigger differential pressure across piston. Your issue sounds very similar.

 

[mweiman]

We have had some issues with getting calipers and the bore for the slide pins are full of rust and dirt at the bottom. That would be worth checking.

 

[WalterJ]

Is there a 'proportioning valve' in the hyd circuit?

 

[GAmes]

Proportioning valves are front to rear, not side to side.

 

[john pavao]

in most brake systems you have to bleed left front right rear then right front to left rear

 

[bigblock_doc]

Piston in the caliper, or slides. But I have found a bad brake hose to be the issue. The inside of the hose is coming apart.
Pressure goes through but won't return when brake is released.

 

[Joe Mc]

He said he replaced hard and soft lines. Wondering if perhaps there's air in ABS module? Was calipers, you did replace both yes? new or reman? Here's a thought, no offense here, check FSM for brake bleeding procedure. Tip if you don't have one yet get yourself a power bleeder, they make doing this job soooo much easier and better.

 

[Joe Mc]

in most brake systems you have to bleed left front right rear then right front to left rear

Not challenging you but. I thought when bleeding you start furthest from m-cyl, then next furthest, etc. IE: R/R, L/R, R/F and then L/F?
Is sequencing you mentioned for AWABS?