What was found
FLIGHT 270, APPROX TWO HOURS AFTER TAKEOFF, EICAS MSG L, ENG BLEED VAL WITH CORRESPONDING L ENG BLEED OFF LIGHT ON P11 PANEL. SINCE THE RT ENG BLEED AIR WAS INOPERATIVE DUE TO A PRIOR MALFUNCTION, NO BLEED SOURCES WERE AVAILABLE TO OPERATE ENG ANTI-ICE, WING ANTI-ICE & ACFT PRESSURIZATION. DECLARED AN EMERGENCY & DIVERTED, FOLLOWED THE PROCEDURES IN THE QRH. R & R THE AIR SUPPLY OVER TEMP SWITCH, 490 DEG F, IAW MM 36-22-01-4. ACFT PASSED ALL PNEUMATIC CHECKS IAW MM 36-11-00-5. ACFT OK FOR SERVICE.