2. © Goodheart-Willcox Co., Inc.

3.  Cooling system diagnosis  Cooling system problems  Thermostat service  Cooling system hose service  Radiator and pressure cap service  Fan belt service  Coolant service  Flushing a cooling system

4. © Goodheart-Willcox Co., Inc.  Gather information:  talk to the owner or service writer to find out as much as possible about the symptoms  diagnosis charts in the service manual can be very helpful

5. © Goodheart-Willcox Co., Inc. On-Board Diagnostics  Cooling-related problems may set a diagnostic trouble code on some systems  use a scan tool to analyze the system  MIL lamp may be on  data will indicate engine temperature  even failure to bleed a system of air could cause erratic temperature sensing

6. © Goodheart-Willcox Co., Inc. Inspecting Cooling System  Perform a visual inspection for:  coolant leaks  loose or missing fan belts  low coolant level  water pump noises  plugged radiator fins  coolant in the oil (oil looks milky)  combustion leakage into coolant

7. © Goodheart-Willcox Co., Inc. Common Problems

8. © Goodheart-Willcox Co., Inc.  Coolant leaks  Overheating  Overcooling

9. © Goodheart-Willcox Co., Inc. Coolant Leaks  External leaks  most common  show up as wet, discolored areas on parts  Internal leaks  caused by cracked block, head or blown head gasket

10. © Goodheart-Willcox Co., Inc. Cooling System Problems A blown head gasket can allow combustion gases to enter the coolant

11. © Goodheart-Willcox Co., Inc. Cooling System Problems Mineral deposits in water jackets can prevent proper heat transfer

12. © Goodheart-Willcox Co., Inc. Cooling System Problems A cracked part or blown gasket can allow coolant to leak into the engine oil

13. © Goodheart-Willcox Co., Inc. Cooling System Pressure Test  Low air pressure is forced into the system  causes coolant to pour or drip from any leak  Install pressure tester on filler neck  Pump the tester to pressurize system  Maximum 14 psi, (96 kPa) or cap rating

14. © Goodheart-Willcox Co., Inc. Cooling System Pressure Test

15. © Goodheart-Willcox Co., Inc. Combustion Leak Test  Checks for the presence of combustion gases in the coolant  Place combustion leak tester on filler neck  Start engine and squeeze tester bulb, pulling air through test fluid  If combustion gases are present in the radiator, fluid changes color

16. © Goodheart-Willcox Co., Inc. Combustion Leak Test Combustion leakage can make the engine overheat

17. © Goodheart-Willcox Co., Inc. Causes of Overheating  Low coolant level  Rust or scale accumulation in water jacket  Stuck thermostat  Delayed ignition  Loose fan belt  Bad water pump or collapsed lower hose  Missing fan shroud or fan problems Causes of Overcooling  Stuck thermostat (open)  Locked fan clutch  Shorted fan switch

18. © Goodheart-Willcox Co., Inc.  A bad pump may leak, fail to circulate coolant, or produce a grinding sound  Causes:  rust in the cooling system  lack of coolant  overtightened belts

19. © Goodheart-Willcox Co., Inc.  A stuck thermostat can cause engine overheating or overcooling  Stuck open–overcooling  loss of efficiency, power, mileage  high emissions  Stuck closed–overheating  engine damage

20. © Goodheart-Willcox Co., Inc. Thermostat Testing  Watch the coolant through the opening in the radiator neck  Cold engine, coolant should not flow  Hot engine, coolant should begin to circulate past the opening  Use a digital thermometer to monitor the temperature of the thermostat housing

21. © Goodheart-Willcox Co., Inc. Thermostat and Housing

22. © Goodheart-Willcox Co., Inc. Thermostat Replacement

23. © Goodheart-Willcox Co., Inc. Thermostat and Housing Special O-ring seal should be replaced anytime the thermostat is removed

24. © Goodheart-Willcox Co., Inc. Bleeding the Cooling System  A bleed valve is sometimes provided  Cars with low hood lines require a bleed screw to empty air pockets  Trapped air can cause overheating or damage from hot spots (buildup of heat)

25. © Goodheart-Willcox Co., Inc. Bleeding the Cooling System  Fill the system  Start and warm the engine  Crack open the bleed screw until all air is purged from the system  NEVER remove a cooling system bleed screw or any clamp on a hot, pressurized system!!!

26. © Goodheart-Willcox Co., Inc. Bleeding the Cooling System

27. © Goodheart-Willcox Co., Inc. Common Hose Problems Hoses deteriorate and become soft and mushy or hard and brittle

28. © Goodheart-Willcox Co., Inc. Hose Replacement A. Loosen clamp, twist and pull hose off B. Clean fitting C. Install new hose and clamp, check for leaks

29. © Goodheart-Willcox Co., Inc.

30. Inspecting the Radiator and Pressure Cap  Inspect radiator fins for debris and rot  Make sure the shroud is in place  Perform pressure cap test  measures cap opening pressure  checks sealing washer condition

31. © Goodheart-Willcox Co., Inc. Pressure Testing a Radiator Cap

32. © Goodheart-Willcox Co., Inc. Radiator Removal

33. © Goodheart-Willcox Co., Inc.  A loose fan belt will slip and squeal  may cause overheating  Inspect the condition and tension  Use a belt tension gauge to adjust belts  A faulty fan can cause overheating, overcooling, vibration and water pump damage  Check for bent blades, cracks or fluid leakage

34. © Goodheart-Willcox Co., Inc. Coolant should be checked and changed at regular intervals  Breaks down and becomes acidic  Rust preventative properties are lost

35. © Goodheart-Willcox Co., Inc. Changing Coolant

36. © Goodheart-Willcox Co., Inc. Checking Coolant Level Coolant should be even with correct marking on reservoir

37. © Goodheart-Willcox Co., Inc. Checking Coolant Level Coolant should be 1” below the top of the tank

38. © Goodheart-Willcox Co., Inc. Testing Coolant Strength  Measures the concentration of antifreeze compared to water  Determines freeze protection  Tool used:  cooling system hydrometer

39. © Goodheart-Willcox Co., Inc. Hydrometer When filled, pointer will float to indicate freeze protection

40. © Goodheart-Willcox Co., Inc.  Cleans rust and scale from the system  May involve running a cleaning chemical through the system  Three Methods:  1. fast flushing  2. reverse flushing  3. chemical flushing

41. © Goodheart-Willcox Co., Inc. 1. Fast Flushing

42. © Goodheart-Willcox Co., Inc. 2. Reverse Flushing

43. © Goodheart-Willcox Co., Inc. 3. Chemical Flushing  Used when scale buildup is causing overheating  Chemical cleaner is added to the coolant  Engine is operated for a specific amount of time  System is flushed with water