I think Ian may be on to something. On mine, and the other 124s I've seen, the power steering hoses are not visible from above. Are you sure you're not looking at a heater hose? The inline pump Ian is referring to is for the "auxillary water pump" which circulates heated coolant to the heater core when the engine is idling.
If so, the pulsing should stop if you turn the climate control system off.