Better Flow, Better Protection

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Jon VanFleet is an ASE Certified Technician and serves as Technical Services Leader at Plews & Edelmann in Dixon, Ill. Photo Jon VanFleet

There are several considerations when it comes to aftermarket power steering coolers.

The power steering cooler aftermarket sector is awash with varying types of replacement solutions, but with so many available, it can be hard to know what to look for. A good understanding of how the cooler operates and how it fits into the entire power steering system helps to make an adequate determination between the options available.

One of the main functions of power steering fluid is to lubricate the inner workings of the mechanical components of the power steering system.  When the fluid temperature is too high, the fluid is less viscous and therefore provides less lubrication for these components, which can lead to failure over time. A power steering cooler is designed to dissipate fluid heat through a system of tubes and cooling fins to bring the fluid to the temperature determined by the Original Equipment (OE) manufacturer. This is where aftermarket coolers often deviate from OE versions, and it becomes difficult to understand how and why they vary. When you look at some models of aftermarket power steering coolers, they deviate significantly from the OE form and fit to a point where they can become almost unrecognizable to the part they are intended to replace.

Tube design

Tube design is an important feature of the cooler because it determines how much fluid will flow through the cooler and for how long that fluid will be able to dissipate heat. Aftermarket coolers with a bar and stock design that differ wildly from the OE cooler run the risk of altering the flow and pressure of the fluid as it moves through the cooler. This can be a problem for a couple of reasons. First, the fluid is not able to spend the necessary time in the cooling process to reach ideal temperature. This doesn’t necessarily mean that the temperature doesn’t drop far enough, but also that it could drop too far, placing unnecessary strain on the power steering components. Additionally, if the fluid pressures and flow rates, both to and from the pump, are altered because of the power steering cooler, the pump is challenged to process these changes. Unchecked, this could lead to functionality and reliability issues with the power steering system.

By itself, tube design is not necessarily key to determining the ideal cooler replacement. Tube design, in tandem with the cooling fin design are what make for a desirable aftermarket cooler. As stated previously, the system depends on the fluid spending the right amount of time in the cooling process to reach the desired temperature. The cooling fins—as designed by the OE—dissipate the heat through airflow over the cooler. Surface area and orientation play a key role in this process as too much (or too little) air flow over the time the fluid is in the cooler will determine how much heat is dissipated from the fluid.  In the previous example of bar and stock designs for aftermarket coolers, the fin sizes are compacted.  It therefore becomes necessary to alter the flows and pressures with this type of cooler to allow the fluid to spend more time in the cooling apparatus as heat is unable to dissipate at the same rate as the original OE design. By combining the single tube with OE styled cooling fins, the heat is dissipated during the expected amount of time the fluid passes through the cooler without altering flows and pressures experienced throughout the entire steering system.

When looking for the next power steering cooler replacement, consider these two visual cues when trying to decide which aftermarket model to use. Find a cooler that matches in shape, style, and size to the OE part, and you will be less likely to compromise system performance to maintain proper fluid temperature.

Single tube construction maintains flow throughout the cooler— versus the bar and stock where the fluid builds in a reservoir and flows through small channels. Photo Plews & Edelmann


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