Dia duit
just had same probelm put a test guage on main hydraulic pump 7/16 unf you should only have about 400psi 20 bar stand by pressure I found my probelm was a broken spring in the small brass check valve on the feed pipe into steering orbital unit and unfortunately it got inside orbital steering unit and partially blocked return to tank which caused hydraulics to overheat after taking over for half hour or so or sooner if driven I hope this helps someone cause it took a long time to find slan go foil from ireland