Engine Mechanical (Service Information): Overview

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Scheme 32: ON-VEHICLE INSPECTION [03/2012 - ]

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INSPECT ENGINE COOLANT Refer to «ON-VEHICLE INSPECTION [03/2012 - ]»(/lexus/gs/iv-2011-2015/remont/cooling-system-mechanical/#engine-cooling-system-inspection__on-vehicle-inspection-032012)
INSPECT ENGINE OIL Refer to «ON-VEHICLE INSPECTION [03/2012 - ]»(/lexus/gs/iv-2011-2015/remont/lubrication-system/#engine-lubrication-system-inspection)
INSPECT AUXILIARY BATTERY Refer to «ON-VEHICLE INSPECTION [03/2012 - ]»(ref-600604-S34252788122014022400000)
INSPECT SPARK PLUG Refer to «ON-VEHICLE INSPECTION [03/2012 - ] - Step 3»(/lexus/gs/iv-2011-2015/remont/ignition-system/#ignition-system-inspection)
INSPECT AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY Remove the air cleaner filter element sub-assembly. Visually check that there is no dirt, blockage, and/or damage to the air cleaner filter element. HINT: If there is any dirt or a blockage in the air cleaner filter element, clean it with compressed air. If any dirt or a blockage remains even after cleaning the air cleaner filter element with compressed air, replace it.
INSPECT V-RIBBED BELT TENSIONER ASSEMBLY Remove the fan and generator V belt. Refer to «REMOVAL [03/2012 - ]»(ref-600560-S22174354152014022400000) . Check that nothing is caught in the tensioner by turning it clockwise and counterclockwise. If a malfunction exists, replace the tensioner. Install the fan and generator V belt. Refer to «INSTALLATION [03/2012 - ]»(ref-600560-S40562405922014022400000) .
INSPECT VALVE LASH ADJUSTER ASSEMBLY Rev up the engine several times. Check that the engine does not emit unusual noises. If unusual noises occur, warm up the engine and idle it for over 30 minutes. Then perform the inspection above again. If any defects or problems are found during the inspection above, perform a lash adjuster inspection.
INSPECT IGNITION TIMING Put the engine in inspection mode. Refer to «INSPECTION MODE PROCEDURE [03/2012 - ]»(ref-600412-S34816019962014022400000) . Warm up the engine and stop the engine. NOTE: A warmed up engine should have an engine coolant temperature of over 80°C (176°F), and an engine oil temperature of 60°C (140°F), and the engine speed should be stabilized. When using the Techstream: Connect the Techstream to the DLC3. Start the engine and idle it. Turn the Techstream on. Enter the following menus: Powertrain / Engine and ECT / Data List / IGN Advance. Standard ignition timing 8 to 18° BTDC at idle NOTE: When checking the ignition timing, the transmission should be in park. HINT: Refer to the Techstream operator's manual for further details. Check that the ignition timing advances immediately when the engine speed is increased. Enter the following menus: Powertrain / Engine and ECT / Active Test / Connect the TC and TE1. Monitor IGN Advance. Perform the Active Test. Standard ignition timing 8 to 12° BTDC at idle NOTE: When checking the ignition timing, the transmission should be in park. HINT: Refer to the Techstream operator's manual for further details. When not using the Techstream: Remove the V-bank cover sub-assembly. Connect the tester probe of a timing light to the wire of the ignition connector for the No. 1 cylinder. NOTE: Use a timing light which can detect the primary signal. NOTE: Confirm the terminal numbers before connecting them. Connecting the wrong terminals can damage the engine. When checking the ignition timing, the transmission should be in park. Using SST, connect terminals 13 (TC) and 4 (CG) of the DLC3. SST: 09843-18040 TEXT IN ILLUSTRATION *a Front view of DLC3 Using a timing light, check the ignition timing. Standard ignition timing 8 to 12° BTDC at idle Remove SST from the DLC3. Check the ignition timing. Standard ignition timing 8 to 18° BTDC at idle Check that the ignition timing advances immediately when the engine speed is increased. Disconnect the timing light from the engine. Install the V-bank cover sub-assembly.
INSPECT ENGINE IDLE SPEED Put the engine in inspection mode. Refer to «INSPECTION MODE PROCEDURE [03/2012 - ]»(ref-600412-S34816019962014022400000) . Warm up and stop the engine. NOTE: A warmed up engine should have an engine coolant temperature of over 80°C (176°F) and an engine oil temperature of 60°C (140°F), and the engine speed should be stabilized. When using the Techstream: Connect the Techstream to the DLC3. NOTE: Switch off all accessories and A/C before connecting the Techstream. Race the engine at 2500 rpm for approx. 90 seconds. Turn the Techstream on. Enter the following menus: Powertrain / Engine and ECT / Data List / Engine Speed. Standard idle speed 950 to 1050 rpm NOTE: When checking the idle speed, the transmission should be in park. HINT: Refer to the Techstream operator's manual for further details. If the idle speed is not as specified, check the air intake system. Disconnect the Techstream from the DLC3. When not using the Techstream: NOTE: Confirm the terminal numbers before connecting them. Connecting the wrong terminals can damage the engine. Using SST, connect the tachometer probe to terminal 9 (TAC) of the DLC3. SST: 09843-18030 TEXT IN ILLUSTRATION *a Front view of DLC3 Race the engine at 2500 rpm for approx. 90 seconds. Check the idle speed. Standard idle speed 950 to 1050 rpm NOTE: When checking the idle speed, the transmission should be in park. If the speed is not as specified, check the air intake system. Disconnect the tachometer from the DLC3.
INSPECT COMPRESSION Put the engine in inspection mode. Refer to «INSPECTION MODE PROCEDURE [03/2012 - ]»(ref-600412-S34816019962014022400000) . Warm up the engine and then stop it. NOTE: A warmed up engine should have an engine coolant temperature of over 80°C (176°F) and an engine oil temperature of 60°C (140°F), and the engine speed should be stabilized. Check for DTCs. Refer to «DTC CHECK / CLEAR [03/2012 - ]»(ref-600436-S38423165432014022400000) . Detach the 4 clips and remove the engine room side cover. Detach the 7 clips and remove the cool air intake duct seal. Remove the bolt and No. 1 air cleaner inlet. Remove the 2 bolts and disconnect the inverter reservoir tank. Disconnect the engine wire from the left side of the engine room. Remove the 3 nuts and disconnect the clamp labeled A using a clip remover. Then, disconnect the clamp labeled B using needle-nose pliers. NOTE: Do not damage the claws of the clamp. Disconnect the manifold absolute pressure sensor connector, VVT sensor connector and 3 ignition coil connectors to disconnect the engine wire. Remove the 3 bolts and 3 ignition coils. Disconnect the engine wire from the right side of the engine room. Remove the 2 nuts and disconnect the clamp. Disconnect the VVT sensor connector and 3 ignition coil connectors to disconnect the engine wire. Remove the 3 bolts and 3 ignition coils. Remove the 6 spark plugs. Refer to «REMOVAL [03/2012 - ]»(ref-600565-S18103547432014022400000) . Disconnect the 4 injector connectors. Disconnect the 2 injector driver connectors by using the following procedures: 1) move the lock lever in the direction indicated by the arrow to release the connector lock, and then 2) disconnect the connectors together with the wire harness locks. TEXT IN ILLUSTRATION *1 Lock Lever *a Release Attach a compression gauge. Connect the Techstream to the DLC3 and turn the power switch on (IG). NOTE: Display the HV battery voltage (VB) in the ECU Data List and make sure the battery voltage is sufficient. Enter the following menus: Powertrain / Hybrid Control / Active Test / Compress Test / On. While cranking the engine, measure the compression pressure. Standard compression pressure 1000 kPa (10.2 kgf/cm 2 , 145 psi) or higher Minimum pressure 700 kPa (7.1 kgf/cm 2 , 102 psi) NOTE: The measurement must be done as quickly as possible. HINT: Always use a fully charged battery to obtain engine speed of 200 rpm or more. Perform the inspection above for each cylinder. Difference between each cylinder 200 kPa (2.0 kgf/cm 2 , 29 psi) or less If the compression pressure is low, add a small amount of engine oil into the cylinder and measure the compression again. HINT: If adding oil increases the compression, the piston rings and/or cylinder bore may be worn or damaged. If the pressure stays low, a valve may be stuck or seated improperly, or there may be leakage from the gasket. Connect the 2 injector driver connectors. Connect the 4 injector connectors. Install the 6 spark plugs. Refer to «INSTALLATION [03/2012 - ]»(ref-600565-S19148093252014022400000) . Connect the engine wire to the right side of the engine room. Install the 3 ignition coils with the 3 bolts. Torque: 10 N*m (102 kgf*cm, 7 ft.*lbf) Connect the VVT sensor connector and 3 ignition coil connectors to connect the engine wire. Connect the clamp and install the 2 nuts. Torque: 10 N*m (102 kgf*cm, 7 ft.*lbf) Connect the engine wire to the left side of the engine room. Install the 3 ignition coils with the 3 bolts. Torque: 10 N*m (102 kgf*cm, 7 ft.*lbf) Connect the manifold absolute pressure sensor connector, VVT sensor connector and 3 ignition coil connectors to connect the engine wire. Connect the 2 clamps and install the 3 nuts. Torque: 10 N*m (102 kgf*cm, 7 ft.*lbf) Install the inverter reservoir tank with the 2 bolts. Torque: 13 N*m (133 kgf*cm, 10 ft.*lbf) Install the No. 1 air cleaner inlet with the bolt. Torque: 5.0 N*m (51 kgf*cm, 44 in.*lbf) Install the cool air intake duct seal with the 7 clips. Install the engine room side cover with the 4 clips. Clear the DTCs. Refer to «DTC CHECK / CLEAR [03/2012 - ]»(ref-600436-S38423165432014022400000) . NOTE: After finishing the procedure, clear all the DTCs and check that the normal DTCs are output.
INSPECT CO/HC HINT: This is a check for determining whether or not the idle CO/HC complies with regulations. Put the engine in inspection mode. Refer to «INSPECTION MODE PROCEDURE [03/2012 - ]»(ref-600412-S34816019962014022400000) . Start the engine. Keep the engine speed at 2500 rpm for approx. 180 seconds. Insert the CO/HC meter testing probe at least 40 cm (1.31 ft.) into the tailpipe during idling. Immediately check CO/HC concentration at idle and/or 2500 rpm. HINT: When performing the 2 mode (2500 rpm and idle) test, follow the measurement order prescribed by the applicable local regulations. If the CO/HC concentration does not comply with regulations, troubleshoot in the order given below. Check the DTCs. Refer to «DTC CHECK / CLEAR [03/2012 - ]»(ref-600436-S38423165432014022400000) . See the chart below for possible causes, and then inspect and correct the applicable causes if necessary. CO HC Symptom Causes Normal High Rough idle 1. Faulty ignitions Incorrect timing Fouled, shorted or improperly gapped plugs 2. Leaky intake and exhaust valves 3. Leaky cylinder Low High Rough idle (Fluctuating HC reading) 1. Vacuum leaks PCV hose Intake manifold Throttle body 2. Lean mixture causing misfire High High Rough idle (Black smoke from exhaust) 1. Restricted air filter 2. Faulty fuel SFI system Faulty pressure Defective engine coolant temperature sensor Faulty ECM Faulty injector Faulty throttle position sensor Faulty mass air flow meter

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Scheme 39: ILLUSTRATION

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Scheme 40: ON-VEHICLE INSPECTION [03/2012 - ]

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INSPECT FAN AND GENERATOR V BELT Check the belt for wear, cracks or other signs of damage. If any of the following defects is found, replace the fan and generator V belt. The belt is cracked. The belt is worn out to the extent that the cords are exposed. The belt has chunks missing from the ribs. Check that the belt fits properly in the ribbed grooves. TEXT IN ILLUSTRATION *a CORRECT *b INCORRECT HINT: Check with your hand to confirm that the belt has not slipped out of the grooves on the bottom of the pulley. If it has slipped out, replace the fan and generator V belt. Install a new fan and generator V belt correctly.

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Scheme 42: REMOVAL [03/2012 - ]

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REMOVE ENGINE ROOM SIDE COVER See step 1
REMOVE COOL AIR INTAKE DUCT SEAL See step 2
REMOVE NO. 1 AIR CLEANER INLET See step 29
REMOVE V-BANK COVER SUB-ASSEMBLY See step 3
REMOVE FAN AND GENERATOR V BELT While releasing the belt tension by turning the belt tensioner counterclockwise, remove the fan and generator V belt from the belt tensioner. While turning the belt tensioner counterclockwise, align its holes, and then insert the 5 mm bi-hexagon wrench into the holes to secure the belt tensioner.

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Scheme 44: INSTALLATION [03/2012 - ]

INSTALL FAN AND GENERATOR V BELT Set the fan and generator V belt onto every part. TEXT IN ILLUSTRATION *1 Engine Water Pump *2 Tensioner *3 Crankshaft While turning the belt tensioner counterclockwise, remove the 5 mm bi-hexagon wrench. NOTE: Put the backside of the fan and generator V belt on the tensioner pulley and idler pulley. Check that the fan and generator V belt is properly set to each pulley. If it is difficult to install the fan and generator V belt, perform the following procedure. Put the fan and generator V belt on every part except the tensioner pulley. Put the fan and generator V belt on the tensioner pulley while turning the belt tensioner counterclockwise. NOTE: Put the backside of the fan and generator V belt on the tensioner pulley and idler pulley. Check that the fan and generator V belt is properly set to each pulley. Check that the belt fits properly in the ribbed grooves. HINT: Make sure to check by hand that the belt has not slipped out of the grooves on the bottom of the pulley.
INSTALL V-BANK COVER SUB-ASSEMBLY See step 116
INSTALL NO. 1 AIR CLEANER INLET See step 75
INSTALL COOL AIR INTAKE DUCT SEAL See step 117
INSTALL ENGINE ROOM SIDE COVER See step 118

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Scheme 45: ILLUSTRATION

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Scheme 46: ILLUSTRATION

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Scheme 47: ILLUSTRATION

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Scheme 48: REMOVAL [03/2012 - ]

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REMOVE INVERTER WITH CONVERTER ASSEMBLY Refer to «REMOVAL [03/2012 - ]»(ref-600413-S32974348392014022400000)
REMOVE ECM Refer to «REMOVAL [03/2012 - ]»(ref-600565-S01816401622014022400000)
REMOVE FUEL PUMP ASSEMBLY Refer to «REMOVAL [03/2012 - ]»(ref-600584-S35801861492014022400000)
REMOVE NO. 1 ENGINE COVER . Refer to «REMOVAL [03/2012 - ] - Step 9»(ref-600584-S30154344742014022400000)
REMOVE INJECTOR DRIVER . Refer to «REMOVAL [03/2012 - ] - Step 10»(ref-600584-S30154344742014022400000)
REMOVE ENGINE COVER . Refer to «REMOVAL [03/2012 - ] - Step 3»(ref-600566-S14922007972014022400000)
REMOVE PCV VALVE SUB-ASSEMBLY . Refer to «REMOVAL [03/2012 - ] - Step 4»(ref-600566-S14922007972014022400000)
DISCONNECT NO. 2 WATER BY-PASS PIPE SUB-ASSEMBLY Remove the bolt and disconnect the No. 2 water by-pass pipe.
REMOVE IGNITION COIL ASSEMBLY . Refer to «REMOVAL [03/2012 - ] - Step 6»(ref-600565-S25351552132014022400000)
REMOVE SPARK PLUG . Refer to «REMOVAL [03/2012 - ] - Step 7»(ref-600565-S25351552132014022400000)
REMOVE NO. 2 OIL LEVEL DIPSTICK GUIDE . Refer to «REMOVAL [03/2012 - ] - Step 13»(/lexus/gs/iv-2011-2015/remont/exhaust/#intake-system-exhaust-system-service-information)
REMOVE CYLINDER HEAD COVER SUB-ASSEMBLY LH Detach the clamps and disconnect the connectors to disconnect the wire harness from the cylinder head cover LH. Remove the 16 bolts, cylinder head cover LH and gasket. Remove the 5 gaskets.
REMOVE CYLINDER HEAD COVER SUB-ASSEMBLY Detach the clamps and disconnect the connectors to disconnect the wire harness from the cylinder head cover. Remove the 15 bolts, cylinder head cover and gasket. Remove the 5 gaskets.
REMOVE SPARK PLUG TUBE GASKET See step 27
REMOVE TIMING CHAIN COVER PLATE Remove the 4 bolts, timing chain cover plate and gasket.
SET NO. 1 CYLINDER TO TDC/COMPRESSION Turn the crankshaft pulley and align the notch with the "0" timing mark of the timing chain cover. Check that the timing marks of the camshaft timing gears are aligned with the timing marks of the bearing caps as shown in the illustration. TEXT IN ILLUSTRATION *A for Bank 2 *B for Bank 1 *1 Paint Mark *2 Timing Mark HINT: If the marks are not aligned, turn the crankshaft again to align the marks. Place paint marks on the chain in alignment with the timing marks on each camshaft timing gear and bearing cap. HINT: Be sure to place the paint marks on 2 links of the chain and on the sprockets of the camshaft timing gears at the locations of the timing marks of the camshaft timing gears.
REMOVE NO. 1 CHAIN TENSIONER ASSEMBLY Turn the crankshaft approximately 30° counterclockwise so that there is some slack in the chain. HINT: This prevents the valves and pistons from interfering with each other. Align the hole in the lever of the tensioner with the hole in the tensioner body as shown in the illustration, and then insert a pin with a diameter of 1.27 mm (0.0500 in.) into the hole. TEXT IN ILLUSTRATION *1 Lever Hole *2 Tensioner Hole Turn the crankshaft clockwise and align the notch with the "0" timing mark of the timing chain cover. Remove the 2 bolts and No. 1 chain tensioner. NOTE: Do not drop the No. 1 chain tensioner or bolts into the timing chain cover.
SEPARATE CHAIN SUB-ASSEMBLY Turn the crankshaft clockwise until it is in the position shown in the illustration so that there is some slack in the chain between the banks. WARNING: As the camshafts turn suddenly, do not touch the camshafts or camshaft timing gears. HINT: When turning the crankshaft, engine oil may spray out of the oil holes. Turn the crankshaft clockwise until it is in the position shown in the illustration so that the chain can be removed easily. TEXT IN ILLUSTRATION *a 5 to 10° HINT: When turning the crankshaft, engine oil may spray out of the oil holes. Remove the chain from the sprocket of the camshaft timing gear and set it on the camshaft timing gear. WARNING: As the camshaft may turn suddenly and pinch your fingers when the chain is removed, pinch the chain and lift it upward to remove it from the sprocket.
REMOVE CAMSHAFT BEARING CAP (for Bank 1) Remove the bolts and bearing caps in the order shown in the illustration. Immediately after removing the bearing caps, install the service bolts and washers in the order shown in the illustration. Torque: 10 N*m (102 kgf*cm, 7 ft.*lbf) TEXT IN ILLUSTRATION *1 Service Bolt and Washers (used to temporarily secure the camshaft housing) *a Part to be removed *b Install the service bolts and washers to temporarily secure the camshaft housing NOTE: Do not install the bearing caps when installing the service bolts and washers. Be sure to follow the numerical order when performing this procedure. Do not allow the service bolts and washers to contact the camshaft. Do not drop the service bolts and washers into the cylinder head. HINT: Arrange the removed parts so that they can be reinstalled in their original locations. Part number for the service bolts used to temporarily secure the camshaft housing: 91551-G0845 (9 bolts) Part number for the service washers used to temporarily secure the camshaft housing: 90201-12028 (18 washers)
REMOVE NO. 2 CAMSHAFT Remove the bolt of the No. 2 chain tensioner. Remove the No. 2 chain tensioner while lifting up the No. 2 camshaft. While lifting up the No. 2 camshaft, pass it through the No. 2 chain and pull it out towards the front of the vehicle to remove it.
REMOVE CAMSHAFT Lift up the rear of the camshaft so that it is at an angle. Remove the chain from the camshaft timing gear and pull out the camshaft and No. 2 chain towards the rear of the vehicle to remove them. NOTE: Do not drop the chain into the gap between the engine and cover. Suspend the chain with a string or equivalent.
SEPARATE CHAIN SUB-ASSEMBLY Turn the crankshaft counterclockwise and align the notch with the "0" timing mark of the timing chain cover. Remove the chain from the sprocket of the camshaft timing gear and set it on the camshaft timing gear. WARNING: As the camshaft may turn suddenly and pinch your fingers when the chain is removed, pinch the chain and lift it upward to remove it from the sprocket.
REMOVE CAMSHAFT BEARING CAP (for Bank 2) Remove the bolts and bearing caps in the order shown in the illustration. Immediately after removing the bearing caps, install the service bolts and washers in the order shown in the illustration. Torque: 10 N*m (102 kgf*cm, 7 ft.*lbf) TEXT IN ILLUSTRATION *1 Service Bolt and Washers (used to temporarily secure the camshaft housing) *a Part to be removed *b Install the service bolts and washers to temporarily secure the camshaft housing NOTE: Do not install the bearing caps when installing the service bolts and washers. Be sure to follow the numerical order when performing this procedure. Do not allow the service bolts and washers to contact the camshaft. Do not drop the service bolts and washers into the cylinder head. HINT: Arrange the removed parts so that they can be reinstalled in their original locations. Part number for the service bolts used to temporarily secure the camshaft housing: 91551-G0845 (8 bolts) Part number for the service washers used to temporarily secure the camshaft housing: 90201-12028 (16 washers)
REMOVE NO. 4 CAMSHAFT SUB-ASSEMBLY Remove the bolt of the No. 3 chain tensioner. Remove the No. 3 chain tensioner while lifting up the No. 4 camshaft. While lifting up the No. 4 camshaft, pass it through the No. 2 chain and pull it out towards the front of the vehicle to remove it.
REMOVE NO. 3 CAMSHAFT SUB-ASSEMBLY Lift up the rear of the camshaft so that it is at an angle. Remove the chain from the camshaft timing gear and pull out the No. 3 camshaft and No. 2 chain towards the rear of the vehicle to remove them. NOTE: Do not drop the chain into the gap between the engine and cover. Suspend the chain with a string or equivalent.
INSPECT CAMSHAFT TIMING GEAR ASSEMBLY Check the lock of the camshaft timing gear assembly. Clamp the camshaft in a vise, and confirm that the camshaft timing gear assembly is locked. NOTE: Be careful not to damage the camshaft. Release the lock pin. TEXT IN ILLUSTRATION *1 Advanced Side Path *2 Retard Side Path *a Open *b Close Rubber Vinyl Tape Cover the 4 oil paths of the cam journal with vinyl tape as shown in the illustration. HINT: The 2 advance side paths are located in the camshaft groove. Plug one of the paths with a rubber piece. Break through the tape on the advance side path and the retard side path on the opposite side of the hole of the advance side path as shown in the illustration. Apply approximately 200 kPa (2.0 kgf/cm 2 , 28 psi) of air pressure to the 2 opened paths. TEXT IN ILLUSTRATION *1 Advanced Side Path *2 Retard Side Path WARNING: Cover the paths with a piece of cloth when applying pressure to prevent oil from spraying. Check that the camshaft timing gear assembly rotates in the advance direction when reducing the air pressure applied to the retard side path. TEXT IN ILLUSTRATION *1 Advance Side Path *2 Retard Side Path *a Hold Pressure *b Decompress HINT: This operation releases the lock pin at the most retarded position. When the camshaft timing gear assembly reaches the most advanced position, release the air pressure first from the retard side path and next from the advance side path. NOTE: Do not release the air pressure from the advance side path first. The gear may abruptly shift in the retard direction and break the lock pin. Check for smooth rotation. Turn the camshaft timing gear assembly within its movable range (21°) 2 or 3 times, but do not turn it to the most retarded position. Make sure that the gear turns smoothly. NOTE: Do not use air pressure to perform the smooth operation check. Check the lock in the most retarded position. Confirm that the camshaft timing gear assembly locks at the most retarded position. Remove the flange bolt and camshaft timing gear assembly. TEXT IN ILLUSTRATION *1 Flange Bolt *2 Straight Pin *a Do Not Remove NOTE: Do not remove the other 3 bolts. If planning to reuse the camshaft timing gear, be sure to release the straight pin lock before installing the camshaft timing gear.
INSPECT CAMSHAFT TIMING EXHAUST GEAR ASSEMBLY Check the camshaft timing exhaust gear lock. Make sure that the camshaft timing exhaust gear assembly locks. Release the lock pin. TEXT IN ILLUSTRATION *1 Advanced Side Path *2 Retard Side Path *a Open *b Close Rubber Vinyl Tape Cover the 4 oil paths of the cam journal with vinyl tape as shown in the illustration. HINT: The 2 advance side paths are located in the camshaft groove. Plug one of the paths with a rubber piece. Break through the tape on the advance side path and the retard side path on the opposite side of the hole of the advance side path as shown in the illustration. Apply approximately 200 kPa (2.0 kgf/cm 2 , 28 psi) of air pressure to the 2 opened paths (the advance side path and the retard side path). TEXT IN ILLUSTRATION *1 Advanced Side Path *2 Retard Side Path WARNING: Cover the paths with a piece of cloth when applying pressure to prevent oil from spraying. Make sure that the camshaft timing exhaust gear assembly rotates in the retard direction when reducing the air pressure applied to the advance side path. TEXT IN ILLUSTRATION *1 Advance Side Path *2 Retard Side Path *a Hold Pressure *b Decompress HINT: The lock pin is released and the camshaft timing exhaust gear assembly turns in the retard direction. When the camshaft timing exhaust gear assembly moves to the most retarded position, release the air pressure first from the advance side path, and then release the air pressure from the retard side path. NOTE: Be sure to release the air pressure from the advance side path first. If the air pressure of the retard side path is released first, the camshaft timing exhaust gear assembly may abruptly shift in the advance direction and break the lock pin or other parts. Check for smooth rotation. Turn the camshaft timing exhaust gear assembly within its movable range (18.5°) 2 or 3 times, but do not turn it to the most advanced position. Make sure that the gear assembly turns smoothly. NOTE: When the air pressure is released from the advance side path and then from the retard side path, the gear assembly automatically returns to the most advanced position due to the advance assist spring operation and locks. Gradually release the air pressure from the retard side path before performing the smooth rotation check. Check the lock at the most advanced position. Make sure that the camshaft timing exhaust gear assembly locks at the most advanced position. Remove the flange bolt and camshaft timing exhaust gear assembly. TEXT IN ILLUSTRATION *1 Flange Bolt *2 Straight Pin *a Do Not Remove NOTE: Be sure not to remove the other 4 bolts. If planning to reuse the gear, be sure to release the straight pin lock before installing the gear.

Engine Mechanical (Service Information): Overview Lexus GS IV