Power Steering Reservoir

What Is a Power Steering Reservoir?

The power steering reservoir is a small but essential component in any hydraulic power steering system. Its primary job is to store and supply hydraulic fluid to the power steering pump, which then pressurizes the fluid and routes it to the steering gear — whether that's a rack-and-pinion assembly or a steering box — to reduce the effort required to turn the wheel. Without a properly functioning reservoir, the entire power steering system is at risk.

Located in the engine bay, power steering reservoirs are typically made of plastic or aluminum and are mounted close to the power steering pump. Most reservoirs include a fluid level indicator — either a translucent body or a built-in dipstick — so owners can monitor fluid levels at a glance. Many also incorporate an internal filter or screen to trap debris and contaminants before they can circulate through the system and cause wear.

Why the Reservoir Matters for Steering Health

Power steering systems generate heat during operation, and the reservoir plays a role in managing that thermal load. A well-designed reservoir helps dissipate heat and allows entrained air and gases to separate from the fluid before it returns to the pump — keeping the system running smoothly and quietly. In performance or racing applications, internal baffles further help prevent fluid cavitation and foaming under aggressive cornering or rapid steering inputs.

Common signs of a failing or leaking reservoir include stiff steering, whining or groaning noises when turning, fluid spots under the vehicle, and fluctuating fluid levels. Because power steering systems are effectively sealed, a drop in fluid level almost always points to a leak somewhere — and the reservoir itself is often the culprit. Replacing a cracked or leaking reservoir promptly is critical; running low on fluid can damage the power steering pump and lead to costly repairs down the line.

What to Consider When Shopping for a Power Steering Reservoir

• OEM vs. Aftermarket: For daily drivers, an OEM-equivalent replacement ensures a perfect fit and restores factory performance. For custom builds or racing applications, billet aluminum reservoirs offer durability and style.
• Vehicle Compatibility: Reservoir designs are highly vehicle-specific. Always verify fitment by year, make, and model before purchasing.
• Material: Plastic reservoirs are common on modern passenger cars; aluminum units are preferred for performance and race builds due to their heat dissipation and durability.
• Internal Baffling: For performance applications, reservoirs with internal baffles help prevent cavitation and fluid aeration during hard driving.
• Filter/Cap Integration: Many OE-style reservoirs include an integrated filter screen. Inspect and replace this filter during any reservoir service.

Top Brands in Power Steering Reservoirs

For European and import vehicles requiring factory-correct replacements, Genuine OEM parts deliver the exact fit and specification your vehicle was built with — no guesswork, no adaptation required. When it comes to Volvo vehicles specifically, Genuine Volvo reservoirs are engineered to Volvo's own standards, ensuring seamless integration with the rest of the power steering system.

For enthusiasts who work on European makes like Audi, BMW, Mercedes-Benz, and Volkswagen, Rein is a trusted name in OE-quality replacement parts. Part of the CRP Automotive family, Rein's reservoir and power steering components are manufactured to be correct in form, fit, and function, making them a reliable choice for import vehicle owners.

Builders working on circle track and road race cars will recognize Allstar Performance as a go-to source for race-ready power steering components. Allstar offers both integral-reservoir pump kits and standalone billet aluminum remote reservoirs designed to handle the demands of competition driving.