TM 10-3930-671 -10 Table 4-2.  Operator Troubleshooting Procedures - CONT. Malfunction Test or Inspection Corrective Action ENGINE (CONT) Step 3. Check radiator coolant level (Para 3-7). If coolant level is low, add coolant (Para 3-7). If coolant level is OK, notify unit maintenance. 5. BLACK EXHAUST SMOKE. Step 1. Check capacity of load on truck (maximum capacity of truck is 4000 lb [1814.4 kg]). If truck is overloaded, reduce size of load. If truck is not overloaded, notify unit maintenance. 6. WHITE EXHAUST SMOKE. Step 1. Check that fuel type is correct (Para 3-9) and not contaminated. If fuel is incorrect type or contaminated, drain fuel tank and refill with correct/clean fuel. If fuel is correct type, notify unit maintenance. 7. TRUCK SLOW TO ACCELERATE. Step 1. Check air cleaner restriction indicator. If yellow flag is raised, notify unit maintenance. If yellow flag is not raised, notify unit maintenance. 8. ENGINE KNOCKING. Step 1. Check engine oil level (Para 3-6 [a]). If oil level is below ADD mark, add oil (Para 3-6 [b]). If oil level is OK, notify unit maintenance. 4-4