What was found
SMOKE OR FUMES IN COCKPIT CLIMBING THRU FL 180 NO INDICATION ON S/O PANEL EXCEPT VERY HIGH DUCT PRESSURE L AND R ABOVE 65 PSI. BLEED SWAPPED TO 2 AND 3 LOWERED PRESSURE TO NORMAL RANGE (BETWEEN 30 40 PSI). REMOVED AND REPLACED HIGH PRESSURE SHUT OFF VALVE USING MM-36-12-042, LEAK CHECK NORMAL. ENTERED COCKPIT TO DEBRIEF CREW, NOTICE NO SMOKE OR ODOR AT THAT TIME. RAN ALL THREE ENGINES, AND WAS UNABLE TO DUPICATE WRITEUP. PER T/S TREE FLOW CHART SUGGEST FOR PRECAUTIONARY MEASURES TO CHANGE HIGH PRESSURE REGULATOR AND HIGH PRESSURE MODULATING SHUT OFF VALVE. REMOVED AND REPLACED LT HIGH PRESSURE REGULATOR REF MM CHP 36-12-051. PERFORMED HIGH PRESSURE BLEED CONTROL SYSTEM TEST, OPS NORMAL REF B727JRH.