ARMY TM 9-6115-670-14&P 4-24 11. ENGINE OVERHEATING. STEP 1.   Check for adequate coolant in radiator overflow tank, and after engine cools check for adequate coolant in radiator (para 4.19.). a.   If radiator overflow tank or radiator is low in coolant, fill with additional coolant. b.   If there is adequate coolant in tank or radiator, proceed to step 2. STEP 2.   Check for blocked, clogged or dirty radiator, exhaust pipe, muffler or vehicle APU compartment doors and vents. a.   If radiator, exhaust pipe, muffler or vehicle APU compartment doors and vents are blocked, clogged or dirty, clean until adequate air flows through APU compartment, muffler, exhaust pipe and radiator. b.   If radiator, exhaust pipe, muffler or vehicle or compartment doors and vents are clean and air flow freely, proceed to step 3. STEP 3.   Check for defective radiator cap (para 5.11.). a.   If the radiator cap is defective, replace cap. b.   If the radiator cap is functioning properly, proceed to step 4. STEP 4.   Check for defective thermostat (para 4.22.). a.   If the thermostat is defective, replace thermostat. b.   If the thermostat is not defective, proceed to step 5. STEP 5.   Check for defective fan belt (para 4.23.). a.   If fan belt is loose, worn or defective, ADJUST or REPLACE belt (para 4.23.). b.   If fan belt is functioning properly, proceed to step 6. STEP 6.   Inspect for collapsed or defective radiator hoses (para 4.24.). a.   If radiator hoses are worn, collapsed or defective, REPLACE hoses (para 4.24.). b.   If radiator hoses are functioning properly, proceed to step 7. STEP 7.   Check fuel filter sediment container for water or other contaminants in the fuel, incorrect grade or fuel type. a.   If the fuel is contaminated, drain entire fuel system including vehicle fuel tank and APU day tank (para 4.32. or 4.33.).  Replace fuel filter (para 4.30.).  Service with clean fuel. Bleed fuel system. b.   If the fuel is uncontaminated, notify next higher level of maintenance.