Play in the steering, a leaking steering box or a drive belt that squeals against the power steering pump are common things to check when the steering turns heavy or jerky. On the Volvo 164, power steering was available as an option (early 164s were delivered without servo), while the four-cylinder 140 models have manual cam-and-roller steering, often called a worm gear – this determines which parts fit this job.
This category gathers wear and mounting parts around the steering box and steering shaft: flex disc and drive belt, lock nut and lock ring, washer, seat, nut and screw. The flex disc between the steering shaft and steering box is a typical wear point and should be checked when there's play; the drive belt controls the power steering pressure and affects how easily the steering wheel turns. Always check model and version against your car before replacing.