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Tài liệu học tập cơ bản khái quát về động cơ và các bộ phận trên ô tô phiên bản tiếng anh. Tài liệu này nhằm giúp chúng ta tiếp cận được cấu tạo chức năng của các bộ phận của xe. Với tài liệu này giúp các bạn sinh viên ngành cơ khí ô tô tiếp cận được những kiến thức cơ bản về ô tô và đồng thời nâng cao kiến thức tiếng anh. Bộ tài liệu này được soạn thảo bởi trường đào tạo và huấn luyện nghề ở Canada.
Chapter 14 Lubricating and Cooling Systems Lubrication System • • • • • • Holds an adequate supply of oil Cools and cleans components Lubricates parts and reduces wear Helps seal the engine Removes contaminates Delivers oil to necessary areas of engine Oil Pump • Pickup screen keeps large particles out of the pump • Oil pressure relief valve prevents excessive oil pressure Oil Filter • • • • • All oil leaving the pump goes to the filter Threads onto a main oil gallery tube Can be single disposable container or a cartridge Some filters use an anti-drainback valve If the filter becomes plugged, a valve opens to allow oil to bypass the filter Engine Oil Passages or Galleries Dipstick • Used to measure the oil level in the oil pan Engine Lubrication Diagnosis and Service • Oil level should be checked periodically • The oil filter is changed with the oil • Oil pump performance can be checked with an oil pressure gauge • Passages and galleries should be cleaned during an engine rebuild Common External Oil Leaks Sludge • • • • • Results from oxidation of the oil The oil begins to solidify and form a gel This gel cannot circulate Can block normal oil paths Signs include low oil pressure, increased oil consumption, increased emissions, and poor driveability Checking Hoses • Hoses deteriorate from the inside • Upper radiator hose suffers the most • Check lower hose reinforcement spring Checking Fans and Fan Clutches • Inspect fan shroud for fit and damage • Damage to belt driven fan can damage water pump and/or radiator • Check fan clutches for oil loss • Replace clutch if it spins with little or no resistance with the engine off Pressure Testing • Applies pressure to system for leak test Leak Detection with Dye • Pour dye into cooling system • Run engine to operating temperature • With engine off, inspect with a black light Combustion Leak Check • Internal leak may be present when there are no visible external leaks but engine is losing coolant or hold pressure • Typically caused by cracked head, head gasket, or warped head Testing the Radiator Cap • Leaking cap will reduce boiling point and cause an overheating condition Hose Clamps • Worn drive clamps often replace spring clamps • Thermoplastic clamps are shrink fit with a heat gun • Readjust a new clamp after a brief run-in period Draining the Coolant • Coolant should be changed every two to four years • Drain reservoir and cooling system • Never pour coolant into a sewer or onto the ground Flushing the Cooling System • Flush the system when coolant is changed and when a water pump is replaced • Power flushing, back flushing, and coolant exchanges force old coolant out and new coolant in • Before using any flush chemical, check to make sure it is safe for the system Refilling and Bleeding • Refill with correct type • Determine the total capacity • Refill system and run engine to operating temperature • Remove air trapped in the system • Refill and recheck coolant level and for any leaks ... years • Drain reservoir and cooling system • Never pour coolant into a sewer or onto the ground Flushing the Cooling System • Flush the system when coolant is changed and when a water pump is... Expansion Tank • Designed to catch and hold coolant passing from radiator cap as the coolant expands Hoses • Made of butyl or neoprene rubber • Cushion engine vibrations and movement • Most vehicles... is directed over the heater core and can be mixed with outside air Electric Cooling Fans • Replaced most belt driven fans • Controlled by a temperature switch and/ or air conditioner switch via