1991 W124

part description > large diameter hydraulic hose that runs from right hand side of engine compartment across the front of the cylinder head and terminates at the power steering pump

fault > the hose pulses every five seconds with engine at idle

Question > is this normal for a car with ASD ... (our 92 w/o ASD does not do this) - This 91 has had this symptom since 82K ( now 195K)

Related information > if I place my hand on the metal lines at the top of the plastic ASD hydraulic reservoir I can also feel the pulse in these lines. Additionaly and I do not know if this has been the case all along but I noticed that the Hyd fluid in the plastic reservoir is quite hot and furthermore that the top surface of the LH fender starting behind the turn signal lamp and extending back 18"+- is quite hot ( not too hot to touch but not just warm eather)

any input appreciated.

Chris