Power Steering Failing?
Basic Diagnostics. The only power steering moving parts are the rack and the pump. In general, worn pumps usually provide good assist when cold, but tend to provide less assist as the power steering fluid warms up. In most of these cases, the surface of the cam ring develops a rippled surface that allows fluid pressure to leak past the vanes or rollers. Nonetheless, to properly diagnose a failing pump, you need a power steering pressure tester. In contrast, worn metering valves in steering racks tend to provide sluggish assist when cold and return to normal assist as the assembly warms up and returns to operational tolerances. [Inquiry:] Problem: power steering pump seems to be failing, 1988 740GLE, 190k miles. Symptoms: Squeeling power steering pump during harder corners at low RPM’s (under 1200 RPM) and at start-up for about a minute. Power steering assistance sometimes intermittent during slow cornering when the wheel is more than 30 degrees off-center. Power steering fluid blackene
