Power Steering Pressure

I have a 1991 - All is well but for the fact that I’m on my 3rd steering rack. So - I’m convinced that the power steering pump I’m using is producing too much pressure for my Jaguar steering rack. Does anyone know what the power steering pump pressure to the rack is supposed to be for a 1991 XJ6 Jaguar? I’m thinking I just need to restrict the pump’s pressure down to match the factor rack’s expected input. I just need that psi number.

I seem to recall that along about 1991-92 Jaguar superseded from troublesome, and leak prone, Adwest racks to German made ZF units that proved much more robust in service. Are you replacing with ZF or Adwest? I also seem to recall that at some point ZFs became the standard warranty replacement units. With the Adwest units dealers were instructed to rebuilt them if leaking under warranty. The success rate with this procedure was not good which also pushed the move to the ZF units. Other’s may clarify.

The latest one was a ZF

A through search in the XJ40 9 volume workshop manual does not turn up a pump pressure but an earlier XJ6 WSM circa 1974 shows 1110 to 1250 PSI as the pump pressure. These used a GM Saginaw belt driven pump but I would think the pressures would be similar in an XJ40.