Overhauling a power steering pump

visits the Steering Specialists to follow them stripping, cleaning and rebuilding the power steering pump from a Mazda MX-5.

From the outside, a power steering pump looks similar to numerous other belt-driven mechanical pumps. However, the pressure it generates is a lot greater than, say, a water pump – usually around 70 Bar, whereas a coolant system operates at around 2 Bar.

There are a range of designs to help generate that pressure. The power steering pump for the Mazda MX-5 Mk2 has a series of vanes that move outwards as the pump is driven by the auxiliary drive-belt. Unlike an impeller inside a water pump, which has fixed-length vanes, these move out when the pump spins, helping to generate pressure. If too much pressure is generated, a relief valve helps to prevent damage.

Typical of any mechanical pump, loss of efficiency can be due to a combination of internal wear, score marks and worn O-rings. If spares are available, such pumps can be stripped and rebuilt to restore them. However, rebuilders such as the Steering Specialists of Wakefield in West Yorkshire have discovered that spares are sometimes impossible to find. As many parts are shared across a range of pumps, they have accumulated a stock of used parts in good condition. The company can also refurbish steering racks and steering boxes.

Having renewed all of his MX-5’S power steering pipes, Rob Hawkins wisely decided to have the power steering pump stripped and checked. The following steps follow it being cleaned, stripped, inspected, rebuilt and tested by Steering Specialists. With the exception of testing, most of the work can be completed on a DIY basis, but unless you have access to spare parts, there’s no guarantee an old power steering pump can be fully refurbished.