unit4

Unit 1 Unit 4 Automobile Repair Learning Objectives: After learning this unit, you should be able to: ​ talk about washing and waxing a car ​ know something about the course th engine troubleshootng ​ understand the ways of expressing trouble shooting ​ learn how to write a letter of complaint Warm-up air cleaner hydraulic lifter clutch pedal fuel gauge air compressor crankshaft thrust bearing carburettor fuel injector Look at the following pictures and speak out the names of automobie parts. ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) Dialogue Bruce: Dear, your car told me that it wanted to take a bath.It hasn’t been washed for almost a month. Frank: Ok, can you help me to call Army’s Auto Beauty Shop for pick-up, mum ? I’ll park it in front of the garage. Bruce: Do they guarantee quality? Frank:Sure. All their workers are experts in washing and waxing. Their steam washing is operated by a computer-controlled machine. Besides, their supervisors are very strict. They do not pass sloppy work. Bruce: Why don’t you drive it there? They will charge a higher price if they come to take it. Frank: Don’t worry about it., mum . They offer free pick-up and delivery. (Mum called Army’s Auto Beauty Shop) Assistant : Hello This is Army’s Auto Beauty Shop .Can I help you ? Bruce： This is Bruce. I think my car want to be cleaned and waxed . Can you come to pick up my car ,? Assistant :Certainly. Can you tell me where you live ? I’ll come to gpick up your car in half an hour.. Bruce: My house is at NO.16 Hongkong Road. How much is a complete clean-up, please? Assistant : Five hundred Yuan including materials and labor. Bruce:: I think it needs a hand wash. Assistant : Exterior and interior? Bruce: Exterior, please. It looks okay inside. We just cleaned the seat last week. Assistant : Will you come to pick it up , or shall we drive it to your place? Bruce:Deliver it to my office, please. When will it be ready? Assistant : About 2 o’clock this afternoon. Bruce:How much should I pay? Assistant :One hundred and fifity Yuan…. You needn’t pay now. Pay when you get the car. Notes sloppy work charge a higher price Useful expressions: 1.​ Exterior and interior? 2.​ Five hundred Yuan including materials and labor. Role Play Try to communicate in the given situation. There is An abnormal audible sound from David’s car during engine acceleration. He wants to repair the car. Text A Engine Troubleshootng Engine Overheating There are many conditions of the automobile that result in overheating，and the degree of overheating is indicated by the temperature gauge on the instrument panel．Some conditions will cause only a slight change in the recorded temperature，other causes will result in a rapid rise in temperature and violent boiling of the coolant．Still others while causing only a slight increase in recorded temperature，while will be more noticeable in engine performance． When troubleshooting the cause for overheating and consequent loss of coolant，the first step is to make careful visual inspection to see if there is any evidence of external leakage．All surfaces of the radiator and its hose connections should be carefully inspected．Leaks generally cause corrosion，which is easily seen．The visual inspection also must include the cooling fan and its drive belt．It is not too unusual for cracks to form in the engine water jacket．When cracks occur，the condition is usually indicated by extreme overheating．The crack is often difficult to locate，because it is not always visible to the naked eye．The condition is also complicated by the fact that the crack usually will close when the engine is cold，and open only when the engine is at operating temperature． Cleaning the Cooling System Unless very severely clogged with rust and hard scale，cooling systems can be cleaned with special chemicals designed for the purpose．The procedure is to fill the system with water，then put in the chemical．The chemical，after dissolving the rust and scale，is flushed from the system．In severe cases of clogged radiators，it is necessary to remove them and have them cleaned by specialized equipment． High Oil Consumption Quite often high oil consumption is blamed on the piston rings．While worn piston rings and cylinder walls do cause increased oil consumption，there are a great number of other things that could be at fault．either singly or in combination． Worn valve guides are also a frequent cause of high oil consumption． When oil is being consumed by passing through the engine, it usually will cause heavy blue smoke to come from the exhaust，particularly after the engine has idled for several minutes． Low 0il Pressure In most cases of low oil pressure，the pressure is satisfactory when the engine is first started up，then it drops as the engine warms up．This condition is almost positive proof that excessive clearance exists at some point，or points，such as connecting rod bearings，main beatings，camshaft beatings etc. When cold, the oil has thickened and does not flow as readily through the clearance．When the oil heats up and thins out，it flows through the worn bearings so fast that the pump cannot maintain sufficient pressure． Chassis and Engine Vibration Consider the case where there is a pronounced vibration in the car at a certain speed range· First of all it is necessary to determine whether the unbalance is in the engine or the chassis，or both．If it is in the engine，or the parts that rotate with the engine，the vibration should occur at the critical engine speed when the car is not in motion． If it is in the chassis，it will occur only when the car is operated at the critical speed．It is most likely to be found in the chassis，because the engine assembly is carefully balanced at the factory． Abnormal Engine Noises and their Causes The fo1lowing listing will point out the most common causes of sound itself and what must be done to eliminate them. 1. Piston slap is a very common noise most noticeable when an engine is cold. A piston that slaps against the cylinder wall produces a hollow, muffled, bell-like sound,quite audible when an engine is operating under load at low rpm .Piston slap results from worn pistons or cylinders, collapsed piston skirts, excessive piston-to-cylinder wall clearance , misaligned connecting rods , or a lack of lubricating oil. Therefore, in order to correct piston slap, it will be necessary to replaced or resize the pistons, rebore the cylinder or replace the sleeves, replace or realign the rods ,or add oil to the engine. 2.An abnormal sound originating from one form of piston-ring problem is audible during engine acceleration. To correct the cause of ring noises, it may be necessary, therefore , to replace the rings ,the pistons , or the sleeves or rebore the cylinders . 3. A sound not frequently heard in an engine is that of a piston ring striking the ring ridge at the top of the cylinder. This particular problem causes a very distinct and high-pitched, metallic rapping or clicking noise audible at all engine speeds but particularly on deceleration. To repair the cause of this sound, it will be necessary to replace the piston pin or connecting rod bearings. 4. A piston-pin knock is noticeable most of the time when an engine is idling .Piston pin noise is usually the result of a worn piston pin，piston—pin boss，pin bushing，or a lack of oil．To correct this problem，install oversize pins，replace the bushings and pins，or service the engine with oil． 5．An abnormal noise that is audible when the engine is running at speeds above 35 miles per hour(mph)without a load is usually the result of loose connecting-rod bearings．Loose rod bearings cause a light to heavy knock or pound, depending on how badly the beating are worn. Connecting- rod bearing noise can be due to a worn bearing ,crankpin ,misaligned rod, or lack of oil. To correct the noise ,it will be necessary to replace the beatings ,service or replace the crankshaft ,realign or replace the rod ,or service the engine with oil . 6．An abnormal noise that is audible upon engine acceleration under load is usually the result of a loose crankshaft main or thrust bearing．Main or thrust bearing noise is usually the result of worn bearings ，crankshaft journals，or a lack of oil．To correct this noise，it will be necessary to replace the bearings ，crankshaft，or service the engine with oil． 7．A 1oose vibration damper or flywheel can also cause abnormal engine noises．This sound is more noticeable during engine acceleration from idle under load or at an uneven idle．but it is less apparent at higher engine rpm or during smoother engine operation．A loose flywheel，on the other hand，sets up either a heavy thump or a light knock at the back of the engine．depending upon the amount of play the flywheel has and the type of engine．You can detect a loose flywheel by shutting off the ignition switch at idle and then turning it on again just before the engine stops rotating．Also，operating the clutch pedal，at the same time the noise is audible at running speeds，will vary the sound enough so that it is easier to identify and then locate its source． 8．Excessive clearance in the valve train produces a noise that is usually more apparent during engine idle rpm than any other time．Valve—train noise is brought about by improper valve adjustment，worn or damaged parts，dirty hydraulic lifter，or lack of clean lubricating oil． In order to correct the cause of the noise，it will be necessary to adjust the valves，replace worn or damaged parts，clean or replace the lifters，or service the engine’s lubrication system． 9．The one abnormal sound unrelated to worn, damaged，loose，or maladjusted engine pans is detonation knock．The noise is most noticeable during acceleration with the engine under load and operating at normal temperature．Excessive detonation is very harmful to the engine，and you should do everything possible to correct the cause as soon as possible．Detonation knock in an engine is usually the product of advanced ignition timing，excessive carbon buildup in the combustion chambers，or use of too low an octane fuel． To correct this malfunction．check the distributor’s advance mechanisms，check and reset the ignition timing, decarbonizes the engine，or recommend a change in fuel to one with a higher octane rating． troubleshootng n. 发现并修理故障 overheating n. 过热 gauge n. 规格，量规，量表 noticeable adj. 显而易见的， 值得注意的 crack n. 裂缝，破裂，裂纹 clog vt. 障碍，阻塞 scale n. 锈，垢 dissolve v. 溶解，解散 blame vt. 谴责，归咎 consumption n. 消费，消费量 pronounced adj. 显著，,断然的，明确的 critical adj. 临界的 cylinder wall n. 汽缸壁 ｍuffled adj. 沉闷的 piston skirt n. 活塞裙 audible adj. 听得见的 misaligned d adj. 线向不正的， 方向偏离的 lubricating oil n. 润滑油 rebore vt. 重镗，镗大（内燃机汽缸）的孔径 realign vt. 校正 abnormal adj. 反常的，异常的 ring ridge n. 活塞环槽 piston-pin n. 活塞销 piston—pin boss n. 活塞销座孔 pitch n. 定调，音调 rap vt. 轻敲 pin bushing n. 销轴瓦 crankshaft main n. 曲轴主轴承 crankshaft thrust bearing n. 推力轴承 crankshaft journal n. 曲轴轴颈 thump n. 重击，重击声 clutch pedal n. 离合器踏板 valve train n. 汽配机构 hydraulic lifter n. 液压挺杆 maladjusted adj. 失调的， 不适应环境的 detonation knock n. 爆震 combustion chamber n. 燃烧室 advance mechanism n. 提前点火装置 octane n. 辛烷 decarbonize vt. 去除积炭 Exercises I. Decide whether the following statements are true (T) or false (F) according to the text. 1. Unless very severely clogged with rust and hard scale，cooling systems can be cleaned with special chemicals designed for the purpose． 2. When oil is being consumed by passing through the engine, it usually will cause heavy black smoke to come from the exhaust，particularly after the engine has idled for several minutes． 3. Out-of-balance tires and propeller shafts are the most common causes of chassis vibration． 4. .An abnormal sound originating from one form of piston-ring problem is audible during engine deceleration. ５. The one abnormal sound unrelated to worn, damaged，loose，or maladjusted engine pans is detonation knock． II.​ Fill in each of the blanks with one of the words or expressions in the box, making changes if necessary: clog, noticeable, scale, dissolve, pronounced, critical, audible maladjusted, pitch, blame 1.​ The street is _______with cars. 2. I've had no time to wash my hair--is it________? 3. They are preparing for war on a large_______. 4. Gold can't be________ in hydrochloric acid. 5. It is a ________tendency for children to play games online. 6. They are men with ________eyes. 7. Even a very low voice is________ in the classroom. 　 8. He________ a tune in a higher key when singing. 9. Tom is a__________ child 10. He _________his failure on his teacher. III. Match the items listed in the following two columns. 1. piston slap a. 汽缸壁 2. cylinder wall b. 活塞敲缸 3. crankshaft journal c. 活塞销座孔 4. piston—pin boss d. 曲轴轴颈 5. valve train e. 活塞裙 6. clutch pedal f. 离合器踏板 7. lubricating oil g. 汽配机构 8. high oil consumption h. 高油耗 9. low oil pressure i. 低油压 10. piston skirt j. 润滑油 IV. Translate the following sentences into Chinese or English. 1. There are many conditions of the automobile that result in overheating，and the degree of overheating is indicated by the temperature gauge on the instrument panel． 2. In severe cases of clogged radiators，it is necessary to remove them and have them cleaned by specialized equipment． 3. When oil is being consumed by passing through the engine, it usually will cause heavy blue smoke to come from the exhaust，particularly after the engine has idled for several minutes． 4. 当要查找引起发动机过热和随之而来的冷却水丧失的原因时，首先要进行仔细的外观检查，确保是否有外部泄漏问 题 快递公司问题件快递公司问题件货款处理关于圆的周长面积重点题型关于解方程组的题及答案关于南海问题 。 5. 冷却系内除非已被铁锈和水垢严重堵塞，否则可以使用特殊的化学物质来清洗。 Text B Fuel Injection Manual Pretest System Checks The following basic checks should be performed and any detected faults corrected before a fuel system test is performed。 Fuel system A．Look for broken or loose fuel lines(metal or rubber)． B．Make sure fuel tank has sufficient fuel(do not rely on fuel gauge)． C．Check for water or other contaminants in fuel． D．Check condition of fuel system related fuses． E. Check condition of fuel tank venting systems． F．Check condition of fuel tank filler cap． Electrical System A．If engine won’t start，check for ignition spark using a test plug．If no spark， repair ignition system． B．Observe check engine lamps or other computer fault indicators． C．Look for ignition wires broken，disconnected or arcing． D．Look for distributor cap or rotor disconnected or arcing． E．Check for component grounds loose or corroded． F．Look for disconnected electrical components． Battery＆Charging System A．Check battery condition．A weak battery will not ensure proper pump delivery or injector triggering．Should be over 12 volts. B．Check basic operation of charging system． C．Look for loose or corroded battery cables． Miscellaneous A．Check vacuum lines for loose or disconnected lines． B．Look for water leaks． C．Look for excessive oil leaks． D．Listen for any audible air leaks，unusual noises，fuel pump buzz(a noisy pump may not be an indication of poor operating condition)，engine rattles or knocks． E．Check valve timing and adjustment． Typical Fuel Injection Pressure Test All pressure tests should be made at idle on the high—pressure side of the system． 1．With engine off，locate fuel pressure port(Schrader Valve)and attach fuel pressure gauge. If no Schrader Valve is provided and system must be opened，residual pressure must be released before fittings are loosened to keep gasoline from spraying all over，possibly causing eye injury or a fire．Connect tester using the correct adapter and access point．Always wrap a shop towel around fitting before loosening． 2．If the adapter you use is a banjo bolt adapter，ours is designed to use with standard banjos. If a car manufacturer uses a nonstandard banjo，more than one washer may be needed on either or both sides of the banjo． 3．With gauge connected to system using proper adapters，reactivate fuel pump，start the engine and check for leaks．If no leaks are detected, observe gauge．Pressure should rise to slightly above operating pressure and then stabilize at operating pressure． 4．Start engine．If an adjustable fuel pressure regulator is used，pressure should be maintained during running．If a compensating fuel pressure regulator is used，pressure should drop approximately 8-9 PSI，depending on manifold vacuum． 5．Locate a flexible hose on the return side and gently squeeze off return flow briefly．Never squeeze a steel braided hose． CAUTION：Some pump designs can be damaged by this test and test should not be performed unless recommended by manufacturer. Observe rapid increase in dead-end pressure．CAUTION：Pressure could exceed 75 PSI and may blow any loose fittings or defective lines．Observe condition of system before this test． 6．If pressure is acceptable，some manufacturers also require a flow test．If so，at this point open the fuel system into a graduated plastic container and observe flow rate．Close system. 7．Turn key off and observe residual pressure．Some manufacturers prescribe a minimum holding time． 8．In conjunction with an injector pulse tester，turn key on，observe pressure，pulse one injector，observe pressure drop，turn key off，move tester to next injector，turn key on，observe pressure，pulse injector，observe drop，turn key off, continue with remaining injector.CAUTION：Do not repeat this test more than manufacturer’s recommendations 9．Deactivate fuel pump and relieve fuel system if necessary．With key off，put bleed—off tubing in a fuel can and press bleed—off valve．If your tester has no bleed—off valve assembly，wrap rags around connections and release slowly． 10．Remove tester and reconnect all lines． 11．Start engine and check for leaks． 12．Remove fuel from all hoses．If fuel remains in gauge hose assembly，connect the smallest banjo bolt adapter into the quick coupler over a fuel container． Hold gauge above hose and fuel will flow into the fuel can． Procedure to Relieve Fuel System Pressure 1．Do not smoke． 2．Wear a pair of safety glasses． 3．Keep a dry chemical (Class B)fire extinguisher near you． 4．Release gas cap with ignition off 5．Disable fuel pump． 6．On some vehicles ,a satisfactory method of disabling the fuel pump(s)is to remove the fuel pump fuse(s)．But on other vehicles，removing the fuses(s) disables the fuel injectors or ignition systems．so another disabling method must be used． 7． Some vehicles not specifically mentioned in our“Fuel Pressure Release” chart may have two fuel pumps．Make sure both are disabled． ． 8．Turn the ignition key on and start the engine． 9．Run the engine until it stalls． 10．Try to restart the engine for 3-5 seconds． For cars with inertia switch pressure relief，engage starter 15 seconds to relieve fuel pressure· 11．Turn ignition key off． Additional Instructions for Testing GM TBI 1．Relieve fuel system pressure． 2．Remove the air cleaner assembly． 3．Temporarily plug the vacuum port on the throttle body． 4．Using proper adapters，install the tester in line between the fuel filter and throttle body． 5. If steel tubing is removed，use two wrenches to prevent damage. 6. On some cars．it is easier to put the car on a lift and test from underneath． 7. On some cars with GM TBI systems，it is hard to install adapters． 8. Reactivate fuel pump，start the engine and check for leaks． 9. When fuel pressure has stabilized after a minute or so，gauge should read 9-13 PSI(62-90kPa)． 10． Deactivate fuel pump，and relieve fuel system pressure．With key off，put bleed-off tubing in a fuel can and press bleed-off valve．If your tester has no bleed—off valve assembly，wrap rags around connections and release slowly． 11． Remove tester and reconnect a11 lines． 12． Start engine and check for leaks． 13． Remove fuel from all hoses．If fuel remains in gauge hose assembly, connect the smallest banjo blot adapter into the quick coupler over a fuel container．Hold gauge above hose and fuel will flow into the fuel can． 14． Remove the plug from the vacuum port and replace air cleaner． Fuel Pressure Diagnosis Fuel Pressure problems generally fall into two categories: higher than normal and lower than normal operating pressures．The fuel supply system is a closed loop system．Fuel is pumped from the tank to the press