2013-2016 Jeep Wrangler (JK) Service & Repair Manual

2010-2016 JEEP WRANGLER SERVICE AND REPAIR MANUAL

2013 ENGINE Cooling System - Wrangler DESCRIPTION DESCRIPTION The cooling system regulates engine operating temperature. It allows the engine to reach normal operating temperature as quickly as possible, maintains normal operating temperature and prevents overheating. The cooling system also provides a means of heating the passenger compartment and cooling the automatic transmission fluid. The cooling system is pressurized and uses a centrifugal water pump to circulate coolant throughout the system. COOLING SYSTEM COMPONENTS The cooling system consists of:  Charge Air Cooler (Diesel engine)  2 Speed Electric Cooling Fan  Aluminum-core radiator with plastic side tanks  Coolant recovery container  Water pump  Combination A/C condenser/transmission oil cooler (automatic transmission)  Thermostat  Hoses and hose clamps OPERATION OPERATION  When engine is cold the thermostat is closed. The cooling system has no flow through the radiator. The coolant flows through the engine, water pump, and heater.  When engine is warm, the thermostat is full open. The coolant flows through the engine, radiator, heater, and water pump.  On the diesel engine coolant flows through the engine, radiator, heater, and water pump.  As coolant expands, some coolant will move to the coolant recovery container. Once the coolant cools, the coolant from the coolant recovery container will move back to the radiator. (Gas engine only) DIAGNOSIS AND TESTING PRELIMINARY CHECKS 2013 ENGINE Cooling System - Wrangler 2013 ENGINE Cooling System - Wrangler

ENGINE COOLING SYSTEM OVERHEATING Establish what driving conditions caused the complaint. Abnormal loads on the cooling system such as the following may be the cause:  Prolonged idle  Very high ambient temperature  Overloaded Truck  Slow traffic  Traffic jams  High speed or steep grades  Snow Plow restricting airflow through cooling module  Debris on front of the grill or the cooling module that is restricting airflow Driving techniques that avoid overheating are:  Idle with A/C off when temperature gauge is at end of normal range.  Increasing engine speed up to 2000 RPM with transmission in park or neutral for more airflow is recommended.  If equipped with a snow plow. Activate the snow plow mode. TRAILER TOWING: Consult Trailer Towing section of the Owner's Manual. Do not exceed the limits. RECENT SERVICE OR ACCIDENT REPAIR: Determine if any recent service has been performed on vehicle that may affect the cooling system. This may be:  Engine adjustments (incorrect timing)  Slipping engine accessory drive belt(s)  Brakes (possibly dragging)  Changed parts. Incorrect water pump or pump rotating in wrong direction due to belt not correctly routed  Reconditioned radiator or cooling system refilling (possibly under filled or air trapped in system).  Service to electrically controlled viscous fan clutch These charts are to be used as a quick-reference only. COOLING SYSTEM DIAGNOSIS CHART NOTE: If investigation reveals none of the previous items as a cause for an engine overheating complaint, refer to the COOLING SYSTEM DIAGNOSIS CHART . CONDITION POSSIBLE CAUSES CORRECTION 2013 ENGINE Cooling System - Wrangler

TEMPERATURE GAUGE READS LOW NOTE: Information on dash cluster is displayed based on broadcast data from PCM. DTC will be set for engine sensor circuit issues. 1. Vehicle is equipped with a heavy duty cooling system. 1. None. System operating normally. 2. Thermostat stuck open 2. Inspect and test thermostat. Refer to THERMOSTAT, DIAGNOSIS AND TESTING . 3. Coolant level low. 3. Fill cooling system. Refer to STANDARD PROCEDURE . 4. Temperature gauge not functioning correctly. 4. Check cluster. Refer to DIAGNOSIS AND TESTING . 5. Engine sensor stuck in range 5. Monitor sensor with scan tool to verify sensor reading changes with increasing temperature. 6. Engine sensor failed out of range. 6. A DTC will be set. 7. Electronically Controlled Viscous Fan Drive/mechanical viscous fan not operating properly. 7. Check Electronically Controlled Viscous Fan Drive. TEMPERATURE GAUGE READS HIGH. COOLANT MAY OR MAY NOT BE LEAKING FROM SYSTEM NOTE: Temperature information displayed on dash cluster and EVIC are based on broadcast data from PCM. If engine temperatures exceed thresholds, power is reduced and a message of 'Oil Temp High - Speed May be Reduced' is displayed on the EVIC. NOTE: Beginning in MY2010, a 200 F thermostat is used in the Ram 2500/3500 pickup with the Cummins Turbo Diesel. It is normal for the coolant temperature gauge to read higher than in previous model 1. Vehicle overloaded, high ambient (outside) temperatures with A/C turned on, stop and go driving or prolonged operation at idle speeds. 1. Temporary condition, repair not required. Notify customer of vehicle operation instructions located in Owner's Manual. 2013 ENGINE Cooling System - Wrangler

years. 2. Electronically-controlled viscous fan clutch not functioning correctly. 2. Troubleshoot and if necessary repair the electronic viscous fan clutch. 3. Temperature gauge not functioning correctly. 3. Check cluster. Refer to DIAGNOSIS AND TESTING . 4. Air trapped in cooling system 4. Drain and refill cooling system. Refer to STANDARD PROCEDURE . 5. Radiator cap faulty. 5. Replace radiator cap. 6. Plugged A/C or radiator cooling fins. 6. Clean all debris away from A/C and radiator cooling fins. 7. Coolant mixture incorrect. 7. Drain cooling system and refill with correct mixture. Refer to STANDARD PROCEDURE . 8. Thermostat stuck shut. 8. Inspect and test thermostat Refer to THERMOSTAT, DIAGNOSIS AND TESTING . 9. Bug screen or winter front being used. 9. Remove bug screen or winter front. 10. Electronically controlled viscous fan drive not operating properly. 10. Check viscous fan. 11. Cylinder head gasket leaking. 11. Check for leaking head gaskets. Refer to DIAGNOSIS AND TESTING . 12. Heater core leaking. 12. Replace heater core. Refer to CORE, HEATER, REMOVAL . 13. Cooling system hoses leaking. 13. Tighten clamps or Replace hoses. 14. Brakes dragging. 14. Check brakes. Refer to DIAGNOSIS AND TESTING . 15. Accessory drive belt. 15. Inspect and replace as necessary. Refer to BELT, SERPENTINE, DIAGNOSIS AND TESTING . 16. Water Pump. 16. Inspect and replace as necessary. 17. Engine sensor stuck in range. 17. Monitor sensor with scan tool to verify sensor reading changes increase in temperature. 18. Temperature sensor failed - Too High 18. Clear the existing overheat fault. Drive the vehicle until thermostat opens. Verify that fault code does not return and coolant 2013 ENGINE Cooling System - Wrangler

does not reach threshold of 230 degrees F. TEMPERATURE GAUGE READING INCONSISTENT (ERRATIC, CYCLES OR FLUCTUATES) NOTE: Information on dash cluster is displayed based on broadcast data from PCM. DTC will be set for engine sensor circuit issues. 1. Heavy duty cooling system, extreme cold ambient (outside) temperature or heater blower motor in high position. 1. None. System operating normally. 2. Temperature gauge or sensor defective. 2. Check cluster or engine coolant temp sensor. Refer to DIAGNOSIS AND TESTING . 3. Temporary heavy usage or load. 3. None. Normal condition. 4. Air trapped in cooling system. 4. Fill cooling system. Refer to STANDARD PROCEDURE . 5. Water pump. 5. Replace water pump. 6. Air leak on suction side of water pump. 6. Check for leak. Refer to DIAGNOSIS AND TESTING . RADIATOR CAP LEAKING STEAM AND OR COOLANT INTO RESERVOIR BOTTLE. (TEMPERATURE GAUGE MAY READ HIGH) 1. Radiator cap defective. 1. Replace radiator cap. 2. Radiator neck surface damaged. 2. Replace radiator. Refer to RADIATOR, ENGINE COOLING, INSTALLATION . HOSE OR HOSES COLLAPSE WHEN ENGINE IS COOLING. 1. Vacuum created in cooling system on engine cool-down is not being relieved through coolant reservoir/overflow system. 1. Replace radiator cap, check vent hose between radiator and reservoir bottle for blockage also check reservoir bottle vent for blockage. NOISY FAN 1. Fan blade(s) loose, damaged. 1. Replace fan blade assembly. 2. Electronically controlled viscous fan drive/mechanical viscous fan. 2. None. Normal condition. 3. Fan blades striking surrounding objects. 3. Locate contact point and repair as necessary. 4. Electronically controlled viscous fan drive/mechanical viscous fan bearing concern. 4. Check viscous fan drive. 5. Electronically controlled viscous fan/mechanical viscous fan stuck on. 5. Check viscous fan drive. 6. Obstructed air flow through radiator. 6. Remove obstruction. 2013 ENGINE Cooling System - Wrangler

LEAK TESTING ULTRAVIOLET LIGHT METHOD INADEQUATE AIR CONDITIONER PERFORMANCE (COOLING SYSTEM SUSPECTED) 1. Radiator and/or A/C condenser air flow obstructed. 1. Remove obstruction and/or clean. 2. Electronically controlled viscous fan drive/mechanical viscous fan not working. 2. Check viscous fan drive. 3. Air seals around radiator damaged or missing. 3. Inspect air seals, repair or replace as necessary. INADEQUATE HEATER PERFORMANCE. GAUGE MAY OR MAY NOT READ LOW. 1. Heavy duty cooling system, and cooler ambient temperatures. 1. None. Normal condition. 2. Obstruction in heater hoses. 2. Remove hoses, remove obstruction. 3. Electronically controlled viscous fan/mechanical viscous fan stuck on. Check viscous fan drive. 4. Water pump damaged. 4. Replace water pump. HEAT ODOR 1. Damaged or missing exhaust system heat shields. 1. Repair or replace damaged or missing exhaust system heat shields. Refer to SHIELD, HEAT, DESCRIPTION . 2. Electronically controlled viscous fan drive//mechanical viscous fan damaged. 2. Check viscous fan drive. 2013 ENGINE Cooling System - Wrangler

Fig. 1: Leak Detection Using Black Light Courtesy of CHRYSLER GROUP, LLC All Jeep models have a leak detection additive added to the cooling system before they leave the factory. The additive is highly visible under ultraviolet light (black light). If the factory original coolant has been drained, pour one ounce of additive into the cooling system. The additive is available through the parts department. Place the heater control unit in HEAT position. Start and operate the engine until the radiator upper hose is warm to the touch. Aim the commercially available black light tool at the components to be checked. If leaks are present, the black light will cause the additive to glow a bright green color. The black light can be used along with a pressure tester to determine if any external leaks exist. PRESSURE TESTER METHOD Fig. 2: Pressurizing System Courtesy of CHRYSLER GROUP, LLC The engine should be at the normal operating temperature. Recheck the system cold if the cause of coolant loss is not located during warm engine examination. Carefully remove the radiator pressure cap from the filler neck and check the coolant level. Push down on the cap to disengage it from the stop tabs. Wipe the inner part of the filler neck and examine the lower inside sealing seat for nicks, cracks, paint, dirt and solder residue. Inspect the reserve/overflow tank tube for internal obstructions. Insert a wire through the tube to be sure it is not obstructed. 1 - TYPICAL BLACK LIGHT TOOL 1 - TYPICAL COOLING SYSTEM PRESSURE TESTER WARNING: Hot, pressurized coolant can cause injury by scalding. 2013 ENGINE Cooling System - Wrangler

Inspect the cams on the outside part of the filler neck. If the cams are bent, seating of pressure cap valve and tester seal will be affected. Replace cap if cams are bent. Attach pressure tester (special tool #7700, Tester, Cooling System) (or an equivalent) to the radiator filler neck. Operate the tester pump to apply 124 kPa (18 psi) pressure to the system. If the hoses enlarge excessively or bulge while testing, replace as necessary. Observe the gauge pointer and determine the condition of the cooling system according to the following criteria:  Holds Steady: If the pointer remains steady for two minutes, there are no serious coolant leaks in the system. However, there could be an internal leak that does not appear with normal system test pressure. Inspect for interior leakage or do the Internal Leakage Test. Do this if it is certain that coolant is being lost and no leaks can be detected.  Drops Slowly: Shows a small leak or seepage is occurring. Examine all connections for seepage or slight leakage with a flashlight. Inspect the radiator, hoses, gasket edges and heater. Seal any small leak holes with a Sealer Lubricant or equivalent. Repair leak holes and reinspect the system with pressure applied.  Drops Quickly: Shows that a serious leakage is occurring. Examine the system for serious external leakage. If no leaks are visible, inspect for internal leakage. Large radiator leak holes should be repaired by a reputable radiator repair shop. INTERNAL LEAKAGE INSPECTION Remove the engine oil pan drain plug and drain a small amount of engine oil. Coolant, being heavier than engine oil, will drain first. Another way of testing is to operate the engine and check for water globules on the engine oil dipstick. Also inspect the automatic transmission oil dipstick for water globules. Inspect the automatic transmission fluid cooler for leakage. Operate the engine without the pressure cap on the radiator until thermostat opens. Attach a pressure tester to the filler neck. If pressure builds up quickly, a leak exists as a result of a faulty cylinder head gasket or crack in the engine. Repair as necessary. If there is no immediate pressure increase, pump the pressure tester until the indicated pressure is within the system range. Vibration of the gauge pointer indicates compression or combustion leakage into the cooling system. WARNING: DO NOT ALLOW PRESSURE TO EXCEED 124 KPA (18 PSI). TURN THE ENGINE OFF. TO RELEASE THE PRESSURE, ROCK THE TESTER FROM SIDE TO SIDE. WHEN REMOVING THE TESTER, DO NOT TURN THE TESTER MORE THAN 1/2 TURN IF THE SYSTEM IS UNDER PRESSURE. WARNING: Do not disconnect the spark plug wires while the engine is operating. CAUTION: Do not operate the engine with a spark plug shorted for more than a minute. The catalytic converter may be damaged. 2013 ENGINE Cooling System - Wrangler

Isolate the compression leak by shorting each spark plug to the cylinder block. The gauge pointer should stop or decrease vibration when spark plug for leaking cylinder is shorted. This happens because of the absence of combustion pressure. COMBUSTION LEAKAGE TEST (WITHOUT PRESSURE TESTER) DO NOT WASTE reusable coolant. If the solution is clean, drain the coolant into a clean container for reuse. Remove thermostat. Refer to THERMOSTAT, REMOVAL . Remove accessory drive belt. Refer to BELT, SERPENTINE, REMOVAL . Add coolant to the radiator to bring the level to within 6.3 mm (1/4 in) of the top of the thermostat housing. Start the engine and accelerate rapidly three times (to approximately 3000 RPM) while observing the coolant. If internal engine combustion gases are leaking into the cooling system, bubbles will appear in the coolant. If bubbles do not appear, there is no internal combustion gas leakage. STANDARD PROCEDURE CLEANING/REVERSE FLUSHING Reverse flushing of the cooling system is the forcing of water through the cooling system. This is done using air pressure in the opposite direction of normal coolant flow. It is usually only necessary with very dirty systems with evidence of partial plugging. CHEMICAL CLEANING If visual inspection indicates the formation of sludge or scaly deposits, use a radiator cleaner, Mopar® Radiator Kleen or equivalent, before flushing. This will soften scale and other deposits and aid the flushing operation. WARNING: Do not remove the cylinder block drain plugs or loosen the radiator draincock with the system hot and under pressure. Serious burns from coolant can occur. CAUTION: Avoid overheating. Do not operate the engine for an excessive period of time. Open the draincock immediately after the test to eliminate boil over of coolant. CAUTION: The cooling system normally operates at 97 - 110 kPa (14 -16 psi) pressure. Exceeding this pressure may damage the radiator or hoses. CAUTION: Be sure instructions on the container are followed. 2013 ENGINE Cooling System - Wrangler

2013-2016 Jeep Wrangler (JK) Service & Repair Manual

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