TIMING BELT & CAMSHAFT TIMING PROCEDURE CAUTION: If a Valve

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 & 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 If timing belt is to be removed, the "painted on" timing marks on the cam gears are no longer valid and must be removed.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

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. Remove fuel line bracket and all upper timing belt covers (3). Remove breather hose from rear camshaft cover, and crankcase vent from breather manifold.

4. Remove camshaft carrier covers. See CAMSHAFT CARRIER & COVERS. Remove side plate bolts from actuator and rotate actuator assembly from tensioner pulley socket, and out of mounting base. See Fig 2. Remove timing belt tensioner pulley. See Fig 2. DO NOT install the rod tip or the tensioner actuator boot in the jaws of a vise or damage to the assembly may occur.

5. Position actuator in vertical position (rod tip down), lightly clamp actuator body in vise. See Fig 4. (Position the tensioner actuator up, so the oil goes to the boot end for at least 5 minutes before refilling the actuator prior to reassembly, if necessary). Actuator assembly uses a tapered bushing between actuator and mounting base. DO NOT lose or damage bushing when removing actuator assembly.

6. Straighten out a standard paper clip .032" (.81mm) diameter, to a minimum straight length of 1.85 " (47 mm). Form a double loop in remaining end of paper clip. See Fig 6. Actuator assembly is filled with oil and removal of the plug may allow oil to escape. DO NOT remove vent plug. Push paper clip through center of vent plug and into pilot hole. Insert a small screwdriver into screw slot inside actuator, behind rubber end plug. 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. This unloads tensioner.

7. Remove timing belt. Rotate crankshaft so No. 1 cylinder is at TDC (Top Dead Center). Mark crankshaft timing indicator (with White paint or equivalent) on crankshaft balancer and front cover only. See Fig 3.

CAUTION: Remove the painted on factory timing marks from all 4 camshafts and the intermediate shaft sprocket (they will no longer be used for timing reference). Prior to installing the Cam Hold Down, ensure that the bolt hole is free of any debris or the camshaft carrier may be damaged.

8. Position camshafts so flat spots are UP for installation of Cam Hold Down. See Fig 8. Install Cam Hold Downs on both camshaft carriers. One on left (front head) and the other on the right (rear head). To remove camshaft sprockets, install Cam Hold Down and remove bolts, taper lock rings, and sprockets by lightly tapping on it with a soft faced hammer. See Fig 7.

Installation

NOTE: Tools required: Cam Hold Down (J-38613-A).

1. Install intermediate drive sprocket and all camshaft sprockets with taper lock rings FINGER TIGHT. Install timing belt in a counterclockwise direction around sprockets. Ensure timing belt teeth are fully engaged with all sprockets. Tighten tensioner pulley bolt to specification. See TORQUE SPECIFICATIONS.

2. If actuator oil has been lost, fill actuator with SAE 5w30 Mobil 1 (or equivalent) synthetic engine oil through end hole. Fill to bottom of plug hole, only when actuator is fully retracted, and pin is installed. Install rubber end plug into rear of the actuator assembly, push until flush and snapped into place. Make sure end plug has sealed against the case. Inspect bushings and appropriate holes to make sure they are clean. Install actuator bushing into side plate. DO NOT lubricate.

3. Install timing belt actuator and actuator side plate. Torque to specification. Rotate pulley assembly into belt a maximum of 132 INCH lbs. (15 Nm.) to allow engagement of actuator shaft into pulley arm socket. Pull lock pin and discard. This releases tensioner. Torque tensioner pulley assembly to 132 INCH lbs. (15 Nm.) counterclockwise to seat pulley into belt. Tighten both right hand (rear bank) camshaft sprocket bolts to 96 ft. lbs. (130 Nm). Remove Cam Hold Down from right hand (rear bank) camshaft carrier. Rotate crankshaft 360 degrees clockwise while looking at front of engine and align crankshaft reference marks. Make sure both right hand (rear bank) camshaft flats are DOWN. Tighten both left hand (front bank) camshaft sprocket bolts to 96 ft. lbs. (130 Nm).

4. Remove Cam Hold Down from left hand (front bank) camshaft carrier. Rotate crankshaft 720 degrees clockwise while looking at front of engine to seat timing belt, and VERIFY correct timing by making sure both camshaft flatspots are UP on one bank, and DOWN on the opposing bank. See Fig 8.

5. Install camshaft carrier covers and bolts. Torque bolts to specification. Install breather hose from rear camshaft cover, and crankcase vent from breather manifold. Install timing belt covers and bolts. Tighten bolts to specification. Install fuel line bracket and bolt. Tighten bolt to specification. Install wiring harness cover at right strut tower.

6. Install spark plug wires. Install PCM electrical connectors. Install power steering lines to pump. Install serpentine belt and tensioner. Tighten serpentine belt tensioner bolt to specification. Install coolant recovery tank. Install upper intake manifold, bolts, and nuts. Tighten to specification. See TORQUE SPECIFICATIONS. Install power brake vacuum hose and wiring loom bracket for rear spark plug wires.

7. Install vacuum lines to upper intake manifold tee. Connect electrical connections to canister purge solenoid and map sensor. Install EGR valve and torque bolts to specification. Connect electrical connectors to EGR. Install PCV valve and vacuum line to throttle body. Install heater hose and bracket to lower intake manifold. Install fuel mounting bracket and bolt, tighten to specification. Connect fuel lines to fuel rail and install fuel rail cover. Connect accelerator and cruise control cables to throttle body. Install air cleaner assembly. Refill cooling system and bleed. See COOLING SYSTEM BLEEDING. Fill power steering system. Install negative battery cable. Fig 1: Removing & Installing Timing Belt

Courtesy of GENERAL MOTORS CORP. Fig 2: Removing & Installing Timing Belt Actuator Pulley

Courtesy of GENERAL MOTORS CORP. Fig 3: Removing Factory Timing Marks

Courtesy of GENERAL MOTORS CORP. Fig 4: Measuring Timing Belt Tensioner Length

Courtesy of GENERAL MOTORS CORP. Fig 5: Installed View Of Timing Belt & Gears

Courtesy of GENERAL MOTORS CORP. Fig 6: Reworking Paper Clip

Courtesy of GENERAL MOTORS CORP. Fig 7: Identifying Cam Sprocket Timing Gears

Courtesy of GENERAL MOTORS CORP. Fig 8: Camshaft Flats Face UP On Both Banks For Installation Of J-38613-A. For Final Timing Reference, Camshaft Flats Are UP On One Bank & DOWN On Other.

Courtesy of GENERAL MOTORS CORP.