Halderman ch027 lecture

© 2011 Pearson Education, Inc.All Rights Reserved

Automotive Technology, Fourth EditionJames Halderman

IN-VEHICLE ENGINE SERVICE

27

27 IN-VEHICLE ENGINE SERVICE



ObjectivesObjectives

• The student should be able to:– Prepare for ASE certification test content

area “A” (General Engine Diagnosis). – Diagnose and replace the thermostat. – Diagnose and replace the water pump. – Diagnose and replace an intake manifold

gasket.




ObjectivesObjectives

• The student should be able to:– Determine and verify correct cam timing. – Replace a timing a belt. – Describe how to adjust valves. – Explain hybrid engine precautions.




THERMOSTAT THERMOSTAT REPLACEMENTREPLACEMENT




Thermostat ReplacementThermostat Replacement

• Failure Patterns– Stuck open– Stuck closed– Stuck partially open– Skewed




Figure 27-1 If the thermostat has a jiggle valve, it should be placed toward the top to allow air to escape. If a thermostat were to become stuck open or open too soon, this can set a diagnostic trouble code P0128 (coolant temperature below thermostat regulating temperature).





• Replacement Procedure– STEP 1: Allow engine to cool for several

hours– STEP 2: Drain coolant into a suitable

container– STEP 3: Remove any components to access

thermostat





• Replacement Procedure– STEP 4: Remove thermostat housing and

thermostat– STEP 5: Replace thermostat housing gasket

and thermostat– STEP 6: Refill cooling system; bleed

trapped air





• Replacement Procedure– STEP 7: Pressurize cooling system– STEP 8: Run the engine and check for leaks– STEP 9: Verify that engine reaching correct

operating temperature




WATER PUMP WATER PUMP REPLACEMENTREPLACEMENT




Water Pump ReplacementWater Pump Replacement

• Need for Replacement– Leaking coolant from the weep hole– Bearing noisy or loose– Lack of proper coolant flow





• Replacement Guidelines– STEP 1: Allow engine to cool to room

temperature– STEP 2: Drain coolant and dispose of

properly or recycle– STEP 3: Remove components to access

water pump





• Replacement Guidelines– STEP 4: Remove water pump assembly– STEP 5: Clean gasket surfaces; install new

water pump and new gasket or seal– STEP 6: Install removed engine

components





• Replacement Guidelines– STEP 7: Fill cooling system with specified

coolant– STEP 8: Run engine, check for leaks, verify

proper operation




Figure 27-2 Use caution if using a steel scraper to remove a gasket from aluminum parts. It is best to use a wood or plastic scraper.




INTAKE MANIFOLDINTAKE MANIFOLDGASKET INSPECTIONGASKET INSPECTION




Intake Manifold Gasket InspectionIntake Manifold Gasket Inspection

• Causes of Failure– Expansion/contraction rate difference

between cast-iron head and aluminum intake manifold (fretting)





• Causes of Failure– Plastic (Nylon 6.6) gasket deterioration

caused by coolant




Figure 27-3 An intake manifold gasket that failed and allowed coolant to be drawn into the cylinder(s).





• Diagnosis of Leaking Intake Manifold Gasket– Visual inspection– Coolant level– Air (vacuum) leak




INTAKE MANIFOLDINTAKE MANIFOLDGASKET REPLACEMENTGASKET REPLACEMENT




Intake Manifold Gasket ReplacementIntake Manifold Gasket Replacement

• STEP 1: Engine off for an hour; drain coolant

• STEP 2: Access to retaining bolts• STEP 3: Loosen fasteners in reverse

order of tightening sequence





• STEP 4: Remove upper intake manifold (plenum); inspect for faults

• STEP 5: Remove lower intake manifold• STEP 6: Thoroughly clean area and

replace intake manifold if needed





• STEP 7: Install intake manifold using new gaskets as specified

• STEP 8: Torque fasteners to factory specifications and in proper sequences

• STEP 9: Reinstall all parts needed for engine to start and run





• STEP 10: Start engine and check for leaks and proper engine operation

• STEP 11: Reset or relearn idle if specified using a scan tool

• STEP 12: Install remaining parts; test drive to verify proper operation and no leaks





• STEP 13: Check and replace air filter if needed

• STEP 14: Change engine oil




Figure 27-4 The lower intake manifold attaches to the cylinder heads.




Figure 27-5 The upper intake manifold, often called a plenum, attaches to the lower intake manifold.




Figure 27-6 Many aftermarket replacement intake manifolds have a different appearance from the original manifold.




TIMING BELTTIMING BELTREPLACEMENTREPLACEMENT




Timing Belt ReplacementTiming Belt Replacement

• Need for Replacement– Exceeds manufacturer’s recommended

replacement interval– Contaminated with coolant or engine oil





• Need for Replacement– Failure (missing belt teeth or broken)





• Timing Belt Replacement Guidelines– STEP 1: Allow engine to cool– STEP 2: Remove components to gain

access to timing belt and marks– STEP 3: If belt not broken, rotate engine so

camshaft and crankshaft timing marks align





• Timing Belt Replacement Guidelines– STEP 4: Loosen or remove tensioner as

needed to remove belt– STEP 5: Replace belt and any other

recommended items– STEP 6: Verify camshaft timing correct by

rotating engine several revolutions





• Timing Belt Replacement Guidelines– STEP 7: Reinstall all parts needed for

engine to start to verify proper operation– STEP 8: Complete reassembly and perform

test drive




HYBRID ENGINE HYBRID ENGINE PRECAUTIONSPRECAUTIONS




Hybrid Engine PrecautionsHybrid Engine Precautions

• Hybrid Vehicle Engine Operation– Gasoline engines used in HEVs and EREVs

can be hazardous– Have idle stop feature– Although engine not running, could start at

any time





• Precautions– Be sure ignition is off and key out of

ignition– Check that “Ready” light is off





• Precautions– Do not touch any circuits that have orange

electrical wires or conduit– Use high-voltage linesman’s gloves when

depowering high-voltage system




Figure 27-8 A Toyota/Lexus hybrid electric vehicle has a ready light. If the ready light is on, the engine can start at anytime without warning.





• Hybrid Engine Service– Low viscosity engine oil used to achieve

maximum fuel economy• SAE 0W-20, SAE 5W-20• Not always stocked item; may have to order





• Hybrid Engine Service– Some require special spark plugs; may

have to order




Figure 27-9 Always use the viscosity of oil as specified on the oil fill cap.




VALVE ADJUSTMENT 1 Before starting the process of adjusting the valves, look up the specifications and exact procedures. The technician is checking this information from a computer CD-ROM-based information system.




VALVE ADJUSTMENT 2 The tools necessary to adjust the valves on an engine with adjustable rocker arms include basic hand tools, feeler gauge, and a torque wrench.




VALVE ADJUSTMENT 3 An overall view of the 4-cylinder engine that is due for a scheduled valve adjustment according to the vehicle manufacturer’s recommendations.




VALVE ADJUSTMENT 4 Start the valve adjustment procedure by first disconnecting and labeling, if necessary, all vacuum lines that need to be removed to gain access to the valve cover.




VALVE ADJUSTMENT 5 The air intake tube is being removed from the throttle body.




VALVE ADJUSTMENT 6 With all vacuum lines and the intake tube removed, the valve cover can be removed after removing all retaining bolts.




VALVE ADJUSTMENT 7 Notice how clean the engine appears. This is a testament of proper maintenance and regular oil changes by the owner.




VALVE ADJUSTMENT 8 To help locate how far the engine is being rotated, the technician is removing the distributor cap to be able to observe the position of the rotor.




VALVE ADJUSTMENT 9 The engine is rotated until the timing marks on the front of the crankshaft line up with zero degrees—top dead center (TDC)—with both valves closed on #1 cylinder.




VALVE ADJUSTMENT 10 With the rocker arms contacting the base circle of the cam, insert a feeler gauge of the specified thickness between the camshaft and the rocker arm. There should be a slight drag on the feeler gauge.




VALVE ADJUSTMENT 11 If the valve clearance (lash) is not correct, loosen the retaining nut and turn the valve adjusting screw with a screwdriver to achieve the proper clearance.




VALVE ADJUSTMENT 12 After adjusting the valves that are closed, rotate the engine one full rotation until the engine timing marks again align.




VALVE ADJUSTMENT 13 The engine is rotated until the timing marks again align indicating that the companion cylinder will now be in position for valve clearance measurement.




VALVE ADJUSTMENT 14 On some engines, it is necessary to watch the direction the rotor is pointing to help determine how far to rotate the engine. Always follow the vehicle manufacturer’s recommended procedure.




VALVE ADJUSTMENT 15 The technician is using a feeler gauge that is one-thousandth of an inch thinner and another onethousandth of an inch thicker than the specified clearance as a double-check that the clearance is correct.




VALVE ADJUSTMENT 16 Adjusting a valve takes both hands—one to hold the wrench to loosen and tighten the lock nut and one to turn the adjusting screw. Always double check the clearance after an adjustment is made.




VALVE ADJUSTMENT 17 After all valves have been properly measured and adjusted as necessary, start the reassembly process by replacing all gaskets and seals as specified by the vehicle manufacturer.




VALVE ADJUSTMENT 18 Reinstall the valve cover being careful to not pinch a wire or vacuum hose between the cover and the cylinder head.




VALVE ADJUSTMENT 19 Use a torque wrench and torque the valve cover retaining bolts to factory specifications.




VALVE ADJUSTMENT 20 Reinstall the distributor cap.




VALVE ADJUSTMENT 21 Reinstall the spark plug wires and all brackets that were removed to gain access to the valve cover.




VALVE ADJUSTMENT 22 Reconnect all vacuum and air hoses and tubes. Replace any vacuum hoses that are brittle or swollen with new ones.




VALVE ADJUSTMENT 23 Be sure that the clips are properly installed. Start the engine and check for proper operation.




VALVE ADJUSTMENT 24 Double-check for any oil or vacuum leaks after starting the engine.

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Halderman ch027 lecture