MODULE 2 RADIATORS AND WATER PUMPS

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1 MODULE 2 RADIATORS AND WATER PUMPS Topic A. Radiator Construction Radiators can be either cross-flow or down-flow. Transmission Oil Cooler Core Tank Header Tank Down-flow radiators force coolant through tubes that are routed from top to bottom. Cross-flow radiators force coolant through tubes that are routed side-to-side. Tank Gaskets Drain Valve A-2 This illustrates all of the parts of a radiator. Parts of a radiator assembly include the: core. tank. tank gaskets. transmission oil cooler. drain valve. tank header. A-5 This radiator, with the tanks mounted on the top and bottom, is called a down-flow radiator. Down-flow radiators: have coolant tanks on the top and the bottom of the cores. are typically taller than they are wide. allow ease in counting the cores and seeing the scale buildup. may be made of aluminum, copper, or brass. A-3 Shown here are the cores of a single core radiator. The radiator core: consists of water tubes that flow horizontally or vertically. removes the heat from the coolant. must be in good working condition to cool properly. CUTAWAY DOWN-FLOW RADIATOR A-5 of your Student CD-ROM for an example of a down-flow radiator cutaway. 12

2 A three-core radiator can have some blockage and no signs of cooling concerns under normal driving conditions due to: scale build up due to corrosion. metal shavings from a defective water pump. coolant additives failing. A-7 A cross-flow radiator can be identified by the side-mounted tanks. Cross-flow radiators: have the coolant tanks mounted on the sides of the cores. are typically wider than they are tall. CUTAWAY CROSS-FLOW RADIATOR A-7 of your Student CD-ROM for an example of a cross-flow radiator cutaway. Topic B. Inspecting For Damage A single-core radiator, with the same amount of blockage under the same driving conditions, may overheat when idling or at high speeds. This can happen because a three-core radiator has the upper half of the radiator open to cool, plus the extra rows of cores. A high cooling capacity radiator can hide many problems if not pushed to its cooling limits. When diagnosing a blocked radiator, it may help to take temperature readings at 9 spots on the radiator core. Areas that may be blocked will show lower temperature readings due to limited coolant flow. A radiator that has the air flow blocked, may have higher temperatures due to the blocking media working as insulation, not permitting air to flow freely and remove the heat B-1 The numbers on this radiator show the nine spots to check for erratic temperature differences in the radiator. Blockage in a radiator can be caused by: debris in the cooling system. corroded metals. chemical breakdown of coolant. B-2 Bent fins will cause reduced air flow. Bent radiator fins: can be caused by gravel, birds, and large bugs. will reduce air flow and increase the operating temperature. may be straightened using a fin comb. 13

3 FIN COMBING Refer to screen B-3v of your Student CD-ROM for a video on straightening bent fins. FIN COMBS B-3v of your Student CD-ROM for an example of fin combs. B-5 This radiator illustrates the absence of radiator cooling fins. Coolant leaks may occur where the: cores and tank header meet. This can be caused by vibration. plastic tank is clamped to the tank header. Age can cause the gasket to deteriorate and allow coolant to seep. Deterioration of cooling fins will cause a cooling system to operate at higher temperatures. Cooling fins: B-4 A deteriorated tank to header gasket can cause coolant leaks. As a radiator ages it may develop leaks. Leaks may develop from radiator tanks due to the brass and the solder joint corroding. Radiator tanks that do not show corrosion on the outside of the tanks can be paper thin from the inside out. Resoldering may help repair the problem. Many times the tank is too thin to make a long-lasting repair. may corrode due to age and chemicals such as salt or coolant. that are missing will cause the engine to operate warmer than designed. The example shown in illustration B-5 will cause the lower portion of the radiator not to cool as designed. 14

4 PRESSURE TESTING Refer to screen B-7v of your Student CD-ROM for a video on pressure testing. Cooling systems must be pressure tested for leaks and to ensure that pressures are maintained. Pressure tests are used to: test the radiator cap for proper operation. pressurize the system to verify that proper pressures are maintained and to identify leaks in the system. When pressure testing a cooling system, visually inspect for leaks near the: hose clamps and part joints. heater box, both inside and outside the vehicle. It may be beneficial to leave the system pressurized for about one hour to watch for a pressure drop. RADIATOR PRESSURE TESTING EQUIPMENT B-7 of your Student CD-ROM for an example of radiator pressure testing equipment. B-8 These are some common styles of radiator caps. Radiator caps: regulate system pressure. keep the system sealed from air and other contaminants. hold the system under pressure to increase the boiling point of coolant. allow coolant to flow from the cooling system to the overflow tank. Faulty radiator caps can cause many cooling system problems. Radiator cap pressure tests help: identify the proper boil-over protection. locate possible cooling system failure areas. Do not pressurize a system beyond the service manual recommendations. Over-pressurizing a cooling system can cause damage to the hoses, radiator, or heater core. When determining whether to repair or replace a radiator, the decision should be made with the insurer, customer, and repair facility involved. 15

5 B-11 These are the two common types of hose clamps. The two types of hose clamps commonly used for radiator and heater hoses are: spring steel. screw band. HOSE CLAMPS Select the Demonstration Icon found on screen B-11 of your Student CD-ROM for an example of the two types of hose clamps. C-2 This electric water pump is from a 1997 Saturn LS. Electric water pumps are: usually for auxiliary purposes. used to increase the flow of coolant. ELECTRIC WATER PUMP C-2 of your Student CD-ROM for an example of an electric water pump. Topic C. Water Pumps Water pumps can be driven by: belts. electric motors. gears. Primary water pumps are generally mechanical driven. Auxiliary water pumps are generally electric. BELT-DRIVEN WATER PUMP C-1 of your Student CD-ROM for an example of a belt-driven water pump. C-3 This gear-driven water pump is from a Chevrolet Corvette LT1 engine. Gear-driven, or direct-drive, water pumps eliminate the chance of belt slippage. Every time the engine moves the pump moves. Gear-driven water pumps: deliver the primary flow of coolant to the engine. may pump coolant in a forward or reverse flow. 16

6 GEAR-DRIVEN WATER PUMP Select the Demonstration Icon found on screen C-3 of your Student CD-ROM for an example of a gear-driven water pump. The leaking means that the water pump needs replacing, or the impeller can grind into the engine block and cause improper clearance problems. WATER PUMP REPLACEMENT Refer to screen C-6v of your Student CD-ROM for a video on water pump replacement. When replacing water pumps: follow the service manual procedures. do not remove too much metal when removing the original gasket material. This can cause leaks. C-4 Centrifugal water pumps draw water in through the center of the pump impeller and out through the sides. Water pumps: draw coolant into the center. push coolant out to the sides. Topic D. Coolant Passages And Water Jackets Coolant in an engine block absorbs heat generated by: combustion. friction. Water jackets can become plugged due to: coolant additive failure. debris buildup. C-5 This leakage from a water pump weep hole means that it s time to change the impeller. The weep hole on a water pump: must be inspected. allows coolant to leak when internal seals or bearings are beginning to fail. 17

7 The cylinders are held in place by a friction ring on the top of the deck and by a ring near the main bearings. If the improper coolant is used in these applications, electrolysis will take place. This will cause aluminum to erode, causing a noise at cold start-up that sounds like a main bearing failure. This is due to the sleeve pounding up and down in the engine. This will occur until the engine is warm and expansion holds the sleeve in place. D-2 This cutaway view shows water jackets through an engine block. Wet cylinders offer the ability to remove and reinstall original factory cylinders with out major engine machining. Topic E. Review Exercise REVIEW Refer to screens E-1 through E-3 of your Student CD-ROM for review questions on radiators and water pumps. 18