Removal & Installation
3.4L (VIN X) Engine
No oil seals need to be disturbed to perform these cover removal procedures.
The 3.4L (VIN X) DOHC engine uses a two-stage camshaft drive. The first stage transfers power from the crankshaft to an intermediate shaft by means of a chain drive. The second stage uses a cogged belt between the intermediate shaft and the individual camshafts. Special care must be taken during timing belt handling and storage to avoid kinks, cuts, etc., which may cause reduced durability. Both chain and belt tension is set by fully automatic tensioners. Timing must be reset if the sprockets are removed from their camshafts. Pins or keys are NOT uses to establish camshaft to crankshaft timing. This is a long procedure, and requires careful work as well as GM's J 38613-A Camshaft Timing Clamps and J 38614 Camshaft Sprocket Holding Tools or their exact equivalents.
- Disconnect the negative battery cable.
- Remove the air cleaner duct.
- Drain the coolant into a suitable container.
- Disconnect the throttle and cruise control cables from the throttle body.
- Remove the engine cosmetic/acoustic cover.
- Relieve the fuel system pressure and disconnect the fuel lines from the fuel rail. Please see Section 5.
- Remove the fuel mounting bracket.
- Remove the heater hose and the bracket at lower intake manifold.
- Remove the PCV valve and vacuum line from the throttle body.
- Remove the EGR valve electrical connector, then unbolt the EGR valve from the upper intake manifold.
- Detach the canister purge solenoid and MAP sensor harness connectors.
- Disconnect the vacuum lines from the upper intake manifold tee.
- Remove the wiring loom bracket from the rear bank spark plug wires.
- Disconnect the power brake booster hose.
- Remove the upper intake manifold.
- Remove the coolant recovery reservoir.
- Remove the accessory drive belt and the drive belt tensioner.
- Remove the power steering pump.
- Detach the PCM connectors.
- Remove the spark plug wires from the spark plugs.
- Remove the wiring harness cover at the right strut tower.
- Remove the fuel line bracket.
- Remove left and right upper timing belt covers, then remove the center cover.
- Disconnect the breather hose from the rear camshaft cover and disconnect the crankcase vent from the breather manifold.
- Remove the left and right camshaft carrier covers.
Inspect the camshaft drive and the camshaft components for wear. Note any evidence of oil or other fluid intrusion. Verify if the camshaft timing belt length is within specification by using the following methods:
- Insert a flat, narrow ruler 0.020 inch (0.5mm) thick along the tensioner pulley.
- Engage the steps in the timing belt tensioner actuator base.
- Note the reading at the top of the tensioner pulley. If the belt is too long, the ruler will drop into the cast groove in the tensioner bracket.
- If the reading at the top of the tensioner pulley is 1.56-1.68 inch (39.6-42.7mm), the timing belt is within an acceptable range.
- If the reading at the top of the tensioner pulley is 1.70-1.84 inch (43.2-46.7mm), replace the timing belt.
- If the belt is less than 1.20 inch (30 mm) wide, it is worn and should be replaced.
- Measure the timing belt tensioner actuator from the centerline of the actuator to the end of the rubber boot. If the measurement reads from 3.20-3.70 inch (80.5-94mm) for a used belt, the belt is in an acceptable range. If the measurement read over 3.7 inch (94mm) for a used timing belt, replace the belt.
- Also check for a broken or cracked tooth or tooth root (especially after 70,000 miles), signs of a leaking camshaft or crankshaft seal, coolant contamination, cracks on the back side of the belt worn teeth so the canvas is showing or breaks across the fibers.
Remove the timing belt tension actuator using the following procedure.
- Remove the bolts and the side plate from the timing belt tensioner actuator. Rotate the drive belt tensioner actuator from the pulley socket and out of the mounting base. Remove the tensioner actuator pulley.
- Position the timing belt tensioner actuator in a vertical position (rod tip down) in a bench vise. CLAMP LIGHTLY.
- Drain the oil in the tensioner actuator to the boot end for at least 5 minutes before refilling the actuator at assembly.
- Straighten out a standard paper clip (0.032 inch diameter with no serrations) to a minimum straight length of 1.85 inch (47mm).
- Form a double loop in the remaining end of the paper clip.
- Remove the rubber plug from the rear of the tensioner actuator. Do not remove the vent plug.
- Push the paper clip through the center hole in the vent plug and into the pilot hole.
- Insert a small screwdriver into the screw slot inside the tensioner actuator and behind the rubber plug end.
- Retract the tensioner actuator plunger by rotating the screw in a clockwise direction until it is fully retracted.
- Push on the paper clip and slowly rotate the screw in a counterclockwise motion until the paper clip engages.
- Remove the timing belt.
- Rotate the crankshaft so the number one cylinder (right side or cowl side, front) is at TDC (Top Dead Center). Mark the timing indicator with white paint (or equivalent permanent mark) on the crankshaft balancer and the front cover.
- Position the camshafts so that the flat spots are "up" for the installation of J 38613-A Camshaft Timing Clamps. Install J 38613-A Camshaft Timing Clamps on both camshaft carriers.
- Remove the camshaft sprocket bolts and the taper lock rings. Remove the sprockets by lightly tapping on them with a soft-faced hammer.
- Clean all parts well. Oil will damage the replacement timing belt. Work as cleanly as possible.
If the camshaft intermediate drive sprocket is to be serviced, use the following procedure:
- Remove the camshaft intermediate drive sprocket retaining bolt.
- Remove the camshaft intermediate drive sprocket using a three-arm puller, similar the a steering wheel puller, and three self-tapping bolts of appropriate size (GM suggests seat belt anchor bolts or an equivalent).
- If the seal is be replaced, pry out the intermediate drive sprocket shaft oil seal. Replace the seal by tapping in a replacement seal with a seal driver or a suitable socket.
- To install the camshaft intermediate drive sprocket, lubricate the seal or the seal running surface of the sprocket.
- Install the sprocket into position on the drive shaft through the oil seal.
- Engage the locating tangs on the shaft sprocket into the mating sockets of the intermediate drive chain sprocket.
- Measure the distance from the front face of the intermediate shaft sprocket to the front cover. If the measurement is more than 1.65 inch (42mm), the tangs are not engaged.
- Lightly lubricate the sprocket retaining bolt and washer and install the bolt. Hold the crankshaft to keep the bolt from rotating. Tighten to 96 ft. lbs. (130 Nm).
If the timing belt idler pulleys are to be serviced, use the following procedure:
- Remove the idler pulley bolts and remove the idler pulleys.
- To install, install the idler pulleys.
- Tighten the idler pulley bolt to 37 ft. lbs. (50 Nm).
- Verify that the pulley rotates freely and is tight on the timing belt front cover.
- Install the camshaft sprockets, lock rings and the bolts, finger-tight. They should turn freely since they will be turned to their timed position by the timing belt.
- Install the timing belt by routing the belt in a counterclockwise motion around the camshaft sprockets.
- Install the timing belt tensioner actuator pulley and tighten the bolt to 37 ft. lbs. (50 Nm).
Prepare the tensioner actuator for installation using the following procedure.
- If any tensioner actuator oil has been lost, refill the tensioner actuator with SAE 5W30 Mobil 1® synthetic engine oil, or equivalent, through the end hole.
- Fill the tensioner actuator to the bottom of the plug hole only when the tensioner actuator is fully retracted and the pin installed.
- Install the rubber plug at the rear of the tensioner actuator. Push the rubber end plug until it is flush and snapped into place.
- Check to make sure that the rubber end plug has sealed against the tensioner actuator case.
- Check to make sure that the tapered fulcrum of the tensioner actuator is properly seated in the bracket bushing. Rotate the tensioner pulley into the timing belt a maximum of 11 ft. lbs. (15 Nm) in order to allow the engagement of the actuator shaft into the pulley arm socket.
- Install the timing belt tensioner actuator busing into the side plate.
- Inspect the tensioner bushings and the appropriate holes for dirt or any foreign material. Do not lubr