Sweeting Performance Review: Delco Moraine Powermaster Electric-Hydraulic Power Brake Systems Explained

Sweeting Performance reviews and technical resources are based on real-world diagnostics, installations, and long-term service experience. One of the most common systems we evaluate is the GM / Delco Moraine Powermaster brake system used primarily on 1986–1987 turbocharged Buick vehicles, including the Grand National and Turbo Regal.

This page provides a complete Powermaster brake system review, including how it works, common problems, parts availability, and the most effective upgrade options such as Hydro-Boost brake conversions.

1. What the Powermaster Brake System Is

The Powermaster brake system is an electric-over-hydraulic brake assist system designed by GM for turbocharged engines that do not produce sufficient vacuum for traditional brake boosters.

• Electric motor-driven hydraulic pump generates system pressure
• Nitrogen-charged accumulator stores pressurized fluid
• Pressure switch cycles the pump on and off
• Integrated power brake booster and master cylinder distributes braking force

This design allows brake assist even at idle or under boost, where vacuum-assisted systems struggle.

2. Powermaster Performance, Reliability, and Common Problems

While innovative for its time, most modern Powermaster brake system reviews highlight reliability concerns as these systems age.

Advantages:

• Independent of engine vacuum
• Consistent assist under turbocharged conditions

Common Problems:

• Accumulator failure causing hard pedal / loss of assist
• Electric motor burnout from frequent cycling, also causing hard pedal / loss of assist
• Pressure switch failure leading to erratic operation
• Inconsistent brake feel (spongy, fading, or overly firm)
• Complete assist loss in severe failure cases

Because of these issues, many owners refer to the system as the “Troublemaster”. In practice, long-term reliability is limited compared to modern alternatives.

3. Parts Availability and Service Challenges

Maintaining the Powermaster system has become increasingly difficult:

• OEM components pressure switches and accumulators can be found but in small quantities, while pump motors are long discontinued
• Rebuilt units are expensive and inconsistent
• Used units expensive and worn
• Limited technician familiarity makes diagnosis harder

Because of this, many owners researching Powermaster brake problems ultimately choose to replace the system.

4. Best Upgrade Options: Hydro-Boost vs Vacuum

Hydro-Boost Conversion (Recommended)

A Hydro-Boost brake conversion replaces the Powermaster with a hydraulic assist system powered by the power steering pump.

• How it works: High pressure hoses tie booster into the belt driven power steering pump to provide brake assist
• Advantages:
  • ✅ High reliability (no electric motor or accumulator)
  • ✅ Strong, consistent braking performance
  • ✅ Modern, serviceable components
• Considerations:
  • Requires hydraulic plumbing
  • Correct master cylinder sizing is critical
  • Dependent on power steering system condition

Hydro-Boost systems are widely considered the most reliable and best-performing upgrade for turbo Buick applications.

Vacuum Booster Conversion (Budget Option)

A vacuum booster conversion replaces the Powermaster with a traditional system.

• Lower upfront cost
• Widely available parts
• Simpler system design

However, vacuum assist can be reduced at idle or under boost, making it less ideal for performance applications.

5. Installation and System Selection Tips

• Converting eliminates reliance on failure-prone Powermaster components
• Hydro-Boost offers the best long-term value
• Match master cylinder bore size to your braking system
• Use proper high-pressure hoses and fittings
• Vacuum conversions require sourcing a different brake pedal
• Properly designed Hydro-Boost kits from Sweeting simplify installation by aligning with the stock brakes pedal

6. System Comparison

Summary: Is the Powermaster Worth Keeping?

While originality matters to some Grand National owners, in practice the Powermaster system is troublesome and more often owners want reliable brakes so that they can enjoy driving their cars confidently.

The Hydro-Boost conversion provides a clear upgrade in both performance and dependability, while vacuum conversions remain a viable lower-cost alternative. Older Grand Nationals, as well as other GM and Buick vehicles of the time, had Hydro-Boost, and non-turbo Regals had vacuum boosters, so both are period correct and stock appearing.

Sweeting Performance supports both restoration and upgrade paths, offering available Powermaster components as well as complete Hydro-Boost conversion solutions, along with installation guidance and technical support.

Frequently Asked Questions

Is the Powermaster brake system reliable?

The Powermaster brake system is generally considered unreliable as it ages. Common failures include the accumulator, pressure switch, and electric motor, which can lead to inconsistent braking or complete loss of assist.

Why do Powermaster brakes fail?

Failures are typically caused by accumulator wear, electric motor overuse, and pressure switch issues, all of which are considered wear items that need to be replaced from time to time.

What is the best replacement for the Powermaster system?

A Hydro-Boost brake conversion is widely regarded as the best replacement due to its reliability and consistent braking performance.

Is Hydro-Boost better than a vacuum brake booster?

Yes, especially for turbocharged applications. Hydro-Boost provides stronger and more consistent assist, while vacuum boosters can be limited under low vacuum conditions.

Can you still buy Powermaster parts?

Accumulators and pressure switches are available in small quantities, but since the pump motors are discontinued investing money into these parts can inevitably be wasted when the pump motor eventually fails and a new one cannot be sourced.

Is it worth keeping the Powermaster system original?

For restoration purposes, some owners keep it original. However, most drivers upgrade for improved safety and reliability.