Halderman ch027 lecture

Objectives 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.

Objectives 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 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).

Thermostat Replacement 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

Thermostat Replacement 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

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

Water Pump Replacement 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

Water Pump Replacement 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

Water Pump Replacement 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 MANIFOLD GASKET INSPECTION

Intake Manifold Gasket Inspection Causes of Failure Expansion/contraction rate difference between cast-iron head and aluminum intake manifold (fretting)

Intake Manifold Gasket Inspection 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).

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

INTAKE MANIFOLD GASKET REPLACEMENT

Intake 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

Intake Manifold Gasket Replacement 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

Intake Manifold Gasket Replacement 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

Intake Manifold Gasket Replacement 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

Intake Manifold Gasket Replacement 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 Belt Replacement Need for Replacement Exceeds manufacturer’s recommended replacement interval Contaminated with coolant or engine oil

Timing Belt Replacement Need for Replacement Failure (missing belt teeth or broken)

Timing Belt Replacement 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 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 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 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

Hybrid Engine Precautions Precautions Be sure ignition is off and key out of ignition Check that “Ready” light is off

Hybrid Engine Precautions 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 Precautions 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 Precautions 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.

Halderman ch027 lecture

More Related Content

What's hot (20)

Viewers also liked (20)

Similar to Halderman ch027 lecture (7)

More from mcfalltj (20)

Recently uploaded (20)

Halderman ch027 lecture

Editor's Notes