52013874AB | Genuine Mopar® Hydraulic Power Brake Booster

1. Primary Vehicle Compatibility

This Hydro-Boost unit is engineered specifically for heavy-duty RAM truck chassis:

• RAM 2500 (Model Years: 2011–2018 / Heavy-Duty 3/4-Ton Trucks)

• RAM 3500 (Model Years: 2011–2018 / Heavy-Duty 1-Ton Pickups & Chassis Cabs)

• RAM 4500 / 5500 (Model Years: 2008–2018 / Commercial Chassis Cabs)

2. Engine Compatibility

Because diesel engines do not produce natural manifold vacuum, this hydraulic booster is essential for high-torque diesel platforms:

• 6.7L Cummins I6 Turbo Diesel (2011–2018)

• 5.7L HEMI V8 Gas & 6.4L HEMI V8 Gas (Heavy-duty 2500/3500 models utilizing hydraulic boost setups)

1. What is it?

Mounted directly between the brake pedal pedal-arm and the master cylinder on the firewall, the unit uses hydraulic power rather than engine vacuum to multiply pedal pressure. It plumbs directly into the vehicle's power steering system, using high-pressure power steering fluid to power the brake assist mechanism.

2. Core Functions & Advantages

• Tailored for Turbo Diesels: Heavy-duty diesel engines like the 6.7L Cummins do not produce engine manifold vacuum. The Hydro-Boost unit overcomes this limitation by using fluid pressure from the steering pump.

• Higher Clamping Force: Hydraulic pressure provides significantly greater hydraulic output to the master cylinder than traditional vacuum boosters, essential for bringing heavy 2500/3500 trucks and heavy towed loads to a stop.

• Emergency Accumulator Cylinder: Features an integrated nitrogen-charged accumulator (the silver cylinder on the body). If the engine stalls or the serpentine belt breaks, the accumulator retains enough pressurized fluid for 1 to 2 emergency power-assisted stops.

1. Extremely Hard or "Stiff" Brake Pedal

The primary function of the Hydro-Boost unit is to amplify foot force on the brake pedal. When internal seals blow or the inner spool valve binds, hydraulic assistance is lost. The brake pedal will feel rock-hard and require extreme physical pressure to stop the vehicle.

2. Fluid Leaks at the Firewall or Master Cylinder

Operating under pressures exceeding 1,200–1,500 PSI, internal O-rings and seals can fail over time. You will notice power steering fluid (ATF+4 or power steering fluid):

• Dripping down the interior firewall behind the brake pedal inside the cab.

• Seeping from the weep hole where the Hydro-Boost connects to the master cylinder.

• Accumulating around the high-pressure hose fitting ports.

3. Simultaneous Steering Noise or Stiff Steering While Braking

Because the booster is plumbed in series with the power steering pump and steering gear, a failing booster can restrict fluid flow through the circuit. Applying the brakes may cause:

• The steering wheel to vibrate or kick back.

• The steering wheel to become stiff or heavy while braking.

• The power steering pump to whine or groan loudly under braking.

4. Slow Brake Pedal Return (Brakes Dragging)

If the internal return spring weakens or the fluid bypass channels become clogged, the brake pedal will slowly creep back to its top rest position after being released. This keeps the brake pads light touching the rotors, causing dragging, overheated brake rotors, and a strong burning smell.

5. Loss of Emergency Reserve Braking

The silver accumulator cylinder on the retains pressurized nitrogen gas to offer 1–2 power-assisted stops if the engine stalls. If the internal bladder in this accumulator loses its charge, you will instantly lose power brakes the second the engine shuts off.