EE WAS OPERATING WATER WAGON (W004) NEAR AUXILIARY STOCKPILE. STOP ENGINE LIGHT WAS ON & ENGINE STOPPED. SMOKE & FIRE WERE COMING THRU THE FLOOR. HE ACTIVATED FIRE SUPRESSION SYSTEM FROM CAB & EXITED. FIRE CAUSED TOTAL DAMAGE TO THE CAB & ALL HOSES & ELEC. WIRING DESTROYED, TIRES DAMAGED.MAINT. DEPT. INVEST: HYD. LINE ON STEERING CYLINER BURST, HYD. OIL ON TURBOCHARGER CAUSED FIRE.