2nd Gen Non-Engine/Transmission Hydroboost Problem

[msamarziya]

I have a 1998 3500 quad cab dually automatic. The hydroboost was leaking fluid so I took it into the shop to be replaced. They have put two boosters on it and have the same problem. When the truck is cold I have no problem with the brake pedal. After the truck is driven about five miles I experience a catch at the pedal when it is applied. I gradually apply more and more pressure to the pedal to get beyond the catch in the pedal to make the brakes engage. Once I get passed the catch in the pedal I hear a "hiss" and then the brakes grab.



So far the shop is stumped. Any help is greatly appreciated.

 

[GAmes]

Just to be clear, they replaced the hydroboost unit, not the master cylinder?

 

[msamarziya]

Yes, the hydroboost was replaced twice and both units operated with the catch in the brake pedal. The original hydroboost unit operated without the catch in the pedal. The original problem was the hydroboost unit was leaking.

 

[GAmes]

Was the power steering fluid flushed and replaced?

 

[msamarziya]

They finally replaced the master cylinder and all is good.