Carmax 6067 170 Turnpike Rd Westborough, MA 01581 YMMS: 1991 Chevrolet Lumina Z34 Sep 3, 2020 Engine: 3.4L Eng License: VIN: Odometer: TIMING BELT INTERFERENCE CAUTION NOTE: CAMSHAFT DRIVE BELTS OR TIMING BELTS - The condition of camshaft drive belts should always be checked on vehicles which have more than 50,000 miles. Although some manufacturers do not recommend replacement at a specified mileage, others require it at 60,000-100,000 miles. A camshaft drive belt failure may cause extensive damage to internal engine components on most engines, although some designs do not allow piston-to-valve contact. These designs are often called "Free Wheeling". Many manufacturers changed their maintenance and warranty schedules in the mid-1980's to reflect timing belt inspection and/or replacement at 50,000- 60,000 miles. Most service interval schedules shown in this section reflect these changes. Belts or components should be inspected and replaced if any of the following conditions exist: Crack Or Tears In Belt Surface Missing, Damaged, Cracked Or Rounded Teeth Oil Contamination Damaged Or Faulty Tensioners Incorrect Tension Adjustment REMOVAL & INSTALLATION Tip: Timing belt CAUTION: For 1996-97 models, this application is an interference engine. Do not rotate camshaft or crankshaft when timing belt is removed, or engine damage may occur. NOTE: The camshaft timing procedure has been updated by TSB bulletin No. 47-61-34, dated December, 1994. REMOVAL Tip: timing 3.4 x motor 1. Disconnect negative battery cable. Remove air cleaner and duct assembly. Drain engine coolant. 2. Remove accelerator and cruise control cables from throttle body. Remove fuel rail cover. Relieve fuel pressure. Remove fuel lines from fuel rail. Remove fuel mounting bracket. 3. Remove heater hose and bracket from lower intake manifold. Remove PCV valve and vacuum line from throttle body. Remove electrical connectors from EGR valve, canister purge solenoid and MAP sensor. Remove EGR valve, and position aside. Remove vacuum lines from upper intake manifold tee. 4. Remove wiring loom bracket for rear spark plug wires. Remove upper intake manifold. Remove coolant recovery tank. Remove serpentine drive belt and drive belt tensioner. 5. Siphon fluid from power steering pump. Disconnect power steering lines and remove power steering pump. 6. On 1991-93 vehicles only, reposition Powertrain Control Module (PCM) out of way. Remove PCM mounting bracket. On 1994-95 vehicles only, disconnect PCM connectors and secure out of way. 7. On all vehicles, note position for reassembly reference and remove spark plug wires from spark plugs. Remove wiring harness cover at right side (passenger) strut tower. Remove fuel line bracket. 8. Remove timing belt covers. Remove breather hose from rear camshaft cover and crankcase vent from breather manifold. Remove camshaft carrier covers. 9. Remove side plate bolts securing timing belt tensioner actuator. Rotate actuator assembly from tensioner pulley socket and out of mounting base. Remove timing belt tensioner pulley. See Fig 1. NOTE: Actuator assembly uses a tapered bushing between the actuator and mounting base. DO NOT lose or damage the bushing when removing the actuator assembly. 10. Position timing belt tensioner actuator in vise with rod tip (rubber boot end) pointing down. 11. Straighten out a standard paper clip (.032" with no serrations) and form a loop at one end. See Fig 2. Remove rubber end plug from rear of tensioner actuator. Push paper clip through end of vent plug and into pilot hole. Insert a small screwdriver into the screw slot inside actuator, behind rubber end plug. CAUTION: Allow oil to flow towards boot end of actuator for at least 5 minutes prior to refilling. NOTE: Tensioner actuator is oil filled. Removal of plug may allow oil to escape. DO NOT remove vent plug. 12. Retract actuator plunger by rotating screw in a clockwise direction until it is fully retracted. Push on paper clip and slowly rotate screw counterclockwise until paper clip engages. Remove timing belt. 13. Rotate crankshaft so that No. 1 cylinder is at TDC of compression stroke. Mark the timing indicator with White paint or equivalent on the crankshaft balancer and front cover. See Fig 3. NOTE: Remove timing marks from camshaft and intermediate shaft sprockets. 14. Position camshafts so that flat spots are "UP" for installation of Camshaft Hold-Down Tools (J 38613- A). Install Camshaft Hold-Down Tools (J 38613-A) on both camshaft carriers. See Fig 4. 15. Remove camshaft sprocket center bolts. Note difference between early and late designs. See Fig 5. Lightly tap on rear of sprockets to remove from camshaft. Fig 1: Identifying Timing Belt Assembly Components Courtesy of GENERAL MOTORS CORP. Fig 2: Reworking Paper Clip Courtesy of GENERAL MOTORS CORP. Fig 3: Aligning Timing Marks Courtesy of GENERAL MOTORS CORP. Fig 4: Installing Camshaft Hold-Down Tools (J 38613-A) Courtesy of GENERAL MOTORS CORP. Fig 5: Identifying Camshaft Timing Sprocket Designs Courtesy of GENERAL MOTORS CORP. INSPECTION 1. To determine if timing belt length is within specifications, measure tensioner actuator from centerline of tensioner actuator to end of rubber boot. See Fig 6. If measurement is 3.2-3.7" (80.5-94.0 mm) for a used belt, the belt is in acceptable range. Replace belt is measurement is more than 3.7" (94 mm). 2. Inspect belt teeth and back side of belt for cracks, tears or other damage. Inspect components for excessive wear or unusual conditions. Note any evidence of oil or other fluid intrusion. Fig 6: Measuring Timing Belt Tensioner Actuator Length Courtesy of GENERAL MOTORS CORP. INSTALLATION 1. Install camshaft sprockets with bolts and locks. Tighten bolts finger tight. Install timing belt onto camshaft sprockets in a counterclockwise direction. Continue installing timing belt, making sure timing belt teeth are fully engaged with all sprockets. 2. Install timing belt tensioner pulley. Tighten timing belt tensioner pulley bolt to 37 ft. lbs. (50 N.m). 3. Install rubber end plug in rear of tensioner assembly until flush. Ensure plug is sealed against case. NOTE: If tensioner oil has been lost, fill tensioner with Mobil 1 SAE 5W-30 synthetic engine oii through plug hole. Fill to bottom of plug hole only when plunger is fully retracted and pin is installed. 4. Install actuator bushing into side plate. Install timing belt actuator and actuator side plate. Tighten side plate bolt to 20 ft. lbs. (27 N.m). NOTE: Ensure actuator bushings and appropriate holes in side plate are clean. DO NOT lubricate bushings. 5. Rotate pulley assembly into timing belt a maximum of 11 ft. lbs. (15 N.m) to allow engagement of actuator shaft into pulley pocket arm socket. Pull the paper clip from the actuator. Retighten pulley assembly 11 ft. lbs. (15 N.m) counterclockwise to seat pulley into belt. 6. Tighten both right hand camshaft sprockets (bank closest to firewall) to 96 ft. lbs. (130 N.m). Remove camshaft hold-down from righthand camshaft carrier. 7. Rotate crankshaft one full turn (360 degrees) clockwise, as viewed from front of engine. Align crankshaft reference marks. See Fig 3. Make sure both righthand camshaft flat spots are down. Tighten both lefthand camshaft sprockets (bank closest to radiator) to 96 ft. lbs. (130 N.m). Remove camshaft hold-down from lefthand camshaft carrier. 8. Rotate engine clockwise (as viewed from front) 2 times to seat belt and verify correct valve timing. DO NOT reverse rotation. Make sure both camshaft flat spots are up on one bank and down on opposing bank. 9. Install camshaft carrier covers. Install breather hose and crankcase vent onto rear cover. Install timing belt covers. 10. To complete installation, reverse removal procedure. Refill cooling system with 50/50 mix of water and coolant. Open air bleed valve on thermostat housing while filling cooling system. Adjust drive belts to proper tension. TIMING BELT & CAMSHAFT TIMING PROCEDURE CAUTION: If a valve timing related problem is caused by a slipped belt, always replace belt. If timing belt is to be removed, the "painted on" timing marks on the cam gears are no longer valid and must be removed. NOTE: For reference, left bank is front bank, and right bank is rear bank. NOTE: Tools required: Cam Hold Down (J-38613-A), Camshaft Sprocket Holding Tool (J-38614) and Torque Angle Meter (J-36660-A). Removal Tip: timing 3.4 x motor NOTE: The camshaft timing procedure has been updated by TSB bulletin No. 47-61-34, dated December, 1994. Before proceeding, see SECTION 6A9 - REVISED CAMSHAFT TIMING PROCEDURE for possible updated information. For belt measurement specification, see TIMING BELT TENSION SPECIFICATIONS. TIMING BELT TENSION SPECIFICATIONS Application In. (mm) Tensioner Measurement New Belt 3.2-3.5 (80.5-89.0) Used Belt 3.2-3.7 (80.5-94.0) 1. Disconnect negative battery cable. Remove air cleaner duct. Drain engine coolant. See COOLING SYSTEM DRAINING. Disconnect accelerator and cruise control cables from throttle body. Remove the fuel injector sight shield. Remove fuel rail cover and relieve fuel pressure. See FUEL PRESSURE RELEASE. Remove fuel lines from fuel rail and remove fuel mounting bracket. 2. Remove heater hose and bracket from lower intake manifold. Remove PCV valve and vacuum line from throttle body. Disconnect electrical connector from EGR. Remove EGR valve. Disconnect electrical connection from canister purge solenoid and MAP sensor. Remove vacuum lines from upper intake manifold tee. Remove wiring loom bracket for rear spark plug wires. Disconnect power brake vacuum hose and remove upper intake manifold support bracket and manifold. Remove coolant recovery tank. 3. Remove serpentine belt and belt tensioner. Remove power steering pump. Disconnect PCM electrical connectors and reposition. Disconnect spark plug wires from spark plugs. Relocate wiring harness cover at right strut tower.