FROM STATEMENT OF OPERATOR "WHILE PERFORMING ROAD MAINTENANCE ACTIVITIES I WAS DRIVING UP A GRADE AT LOW SPEED WHILE IN FOUR WHEEL DRIVE AND IN LOW GEAR. THE FIRST INDICATION OF A PROBLEM WAS A SUDDEN BURST OF SMOKE FROM UNDER THE HOOD ACCOMPANIED BY THE ENGINE OIL LIGHT COMING ON. I TRIPPED THE HOOD RELEASE, WENT TO THE FRONT OF THE VEHICLE TO OPEN THE HOOD. THE SMOKE FROM THE ENGINE COMPARTMENT PREVENTED ME FROM SAFELY LOCATING THE HOOD RELEASE. I THEN RETRIEVED THE FIRE EXTINGUISHER FROM THE VEHICLE AND APPLIED IT THE BEST I COULD TO THE ENGINE COMPARTMENT. AT THE SAME TIME ANOTHER EMPLOYEE RETRIEVED AN ADDITIONAL 2 FIRE EXTINGUISHERS FROM ANOTHER FOREST SERVICE TRUCK AND APPLIED THEIR CONTENTS IN A SIMILAR FASHION. THE APPLICATION WAS INSUFFICIENT TO EXTINGUISH THE FIRE. OVER THE SUBSEQUENT HALF HOUR TO 45 MINUTES THE VEHICLE BECAME FULLY ENGULFED IN FIRE. THE SECOND OPERATOR SAID WHEN HE SEEN THE SMOKE HE RAN UP TO THE FRONT SIDE OF THE TRUCK AND COULD SEE FLAMES IN THE ENGINE COMPARTMENT AND AT THAT TIME THEY TRIED TO EXTINGUISH THE FIRE USING 3 5ABC FIRE EXTINGUISHERS. AFTER DEPLETING THE EXTINGUISHERS THEY MOVED BACK AND UNHOOKED THE ROCK RAKE THEY WERE PULLING AND WAITED FOR THE FIRE RESPONSE TO ARRIVE AT WHICH TIME THE VEHICLE WAS TOTALLY ENGULFED. *TR