TM 10-3930-671-24 F. Excessive Smoke White Smoke - May indicate misfiring. 1. Low engine temperature (cold engine) Check thermostat. Increase engine temperature. 2. Faulty injectors Cut out individual injectors with engine running. Clean and test faulty nozzle for pressure, leakage, and spray pattern. 3. Poor Fuel Use diesel fuel per specifications. 4. Poor compression See Item G. Recommendations. 5. Coolant leak into combustion chamber Check head gasket. 6. Insufficient lubricating oil Check oil level. Blue Smoke - Indicates high oil consumption 1. Worn or stuck piston rings See Item I. High Oil Consumption. 2. Low engine coolant temperature Check thermostat. 3. Worn valve guides, valve stem, or valve Replace. stem seals Black Smoke 1. Excessive fuel rate Check pump by authorized service center. 2. Overloading of engine Reduce load. Keep engine speed up. 3. Restriction in air supply Service air cleaner and connections. 4. Low engine coolant temperature Check thermostat. 5. Faulty injectors Test and repair or replace. G. Poor Compression (Under 325 psi @ 150 rpm) 1. Valves holding open - no tappet clearance  Adjust tappet clearance per specifications. 2. Leaky cylinder head gasket Clean head and block surfaces. Replace gasket and torque bolts to specification. 3. Wrong valve timing Check and correct, as necessary. 4. Burned or sticking valves or incorrect Clean and grind valves. Reface or replace, valve timing as necessary. 5. Broken or weak valve springs Check and replace springs not to specs. 6. Piston rings worn or broken Replace with recommended service kit. 7. Worn pistons and cylinder bores Overhaul, rebore, and replace pistons. H. Low Oil Pressure 1. Low oil level Add oil to correct dipstick level. 2. Oil pressure gauge or line faulty Inspect lines. Check with master gauge. 3. Oil viscosity too light, or oil diluted Change oil to correct specifications. 4. Dirt in relief valve or broken spring Clean valve, or replace spring. 5. Oil suction screen plugged Remove screen and clean in solvent. 6. Worn bearings Replace. 7. Worn oil pump Remove, repair, or replace pump. 8. Oil pick-up tube O-ring damaged Replace. or missing 9. Oil leaks Locate and repair. F-70