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The consequences of overfilling the power steering fluid reservoir are no different from the inherent dangers of filling the engine with too much oil. As with all the fluids required to keep any car in tip-top shape, vehicles with hydraulic or hydroelectric power steering systems require a sufficient amount of fluid to operate smoothly. Power steering fluid capacities vary from vehicle to vehicle. However, for top offs and flushes, you’ll typically need to purchase between one and two liters of replacement fluid.
In most cars, the fluid reservoir is a semi-translucent plastic container with MAX and MIN markings, making it easier to see the fluid level. However, some vehicles have metal reservoirs with a removable cap and dipstick. The dipstick will have similar MIN and MAX markers to identify the fluid level.
Overfilling the power steering system can cause fluid to spill out of the reservoir when it pressurizes and heats up, which could potentially splash on drive belts, the alternator, or other components, causing slippage, wear, or damage. Since power steering fluid is a lubricant, it can cause a huge mess inside the engine bay and on your garage floor. Meanwhile, too much fluid can raise the hydraulic pressure of the system. When this happens, there’s imminent danger of damaging the power steering pump, cracking hydraulic hoses, and leaks from damaged seals.
Underfilling your power steering fluid is just as risky as overfilling
Here’s the kicker: The hydraulic power steering is a sealed, closed-loop system, and it doesn’t require frequent top-offs. If you find yourself often refilling the reservoir after checking your power steering fluid, it might be time to visit a mechanic to diagnose leaks or other faults. Power steering leaks might not seem serious at first, but small leaks can become significantly large enough for the system to run dangerously low on fluid, causing loud noises, system overheating, and accelerated wear and tear of hydraulic components.
Running a vehicle with insufficient power steering fluid can damage the pump with excess heat and friction. And when the pump fails, there will be no power assistance from the steering rack. Your car will still run, but it will be difficult and uncomfortable to drive, especially when parking or maneuvering. Topping it off with fluid is a Band-Aid solution to what could otherwise be a simple fix, so be wary of power steering leaks before they turn into a costlier repair.
You overfilled the power steering reservoir. What should you do now?
Before we explain how to deal with an overfilled power steering reservoir, it’s important to confirm that you added the right kind of fluid. Depending on the make and model of the vehicle, the system may require automatic transmission fluid (ATF) or synthetic power steering fluid. Knowing what kind of power steering fluid your vehicle uses is just as important as filling the reservoir properly, so it’s wise to refer to your car’s owner’s manual to learn the right type.
So, what happens if you accidentally add too much power steering fluid to the reservoir? Don’t despair. Grab a turkey baster, large syringe, or a fluid extractor pump to suck up the excess liquid. Then, confirm that the fluid level is within the MIN and MAX markings. If the fluid has a deep brown color or foamy consistency, you should consider replacing it. Manufacturers typically recommend changing the power steering fluid every five years or 50,000 miles, but the numbers may vary depending on the type of vehicle.
