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Subject: Operating Characteristics of the Electro-Viscous (EV) Fan Clutch and Diagnostic Tips for Cooling Fan Noise, Delayed Transmission Shifts and/or Engine Revving Too High Models: 2004-2006 Buick Rainier 2002-2006 Chevrolet TrailBlazer, TrailBlazer EXT 2006 Chevrolet TrailBlazer SS 2002-2006 GMC Envoy, Envoy XL 2004-2005 GMC Envoy XUV 2002-2004 Oldsmobile Bravada 2005-2006 Saab 9-7X with 4.2L I-6, 5.3L V-8 or 6.0L V-8 Engine (VINs S, P, M, H – RPOs LL8, LM4, LH6, LS2) Date/VIN Breakpoints for Vehicles with New EV Fan Clutch Vehicles built after and including the Date or VIN Breakpoints listed in the table shown are equipped with the new electro-viscous (EV) fan clutch. Vehicles of any model year listed in “Models Affected” with labor code J3390 (claimed after June 8, 2005) with P/N 15293048 in Claim History may also be equipped with this new EV fan clutch.

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An exhaust leak at the exhaust manifolds may be evident on some vehicles. This may be due to heat causing a reduction in bolt torque on the exhaust manifolds. ACTION Install new exhaust manifold bolts. Refer to the following Service Procedure and Part Application Chart for details. SERVICE PROCEDURE 1. If an exhaust leak exists at the exhaust manifold due to a reduction in bolt torque, remove the manifold bolts and the exhaust manifold and check the overall flatness of the manifold. The manifold should not exceed 0.25 mm (0.010″) out- of-flat. Refer to the appropriate model/year Service Manual for manifold removal procedures. 2. If the vehicle is covered under the emissions warranty period, replace the manifold if it is out-of-flat. If the vehicle is out of the emissions warranty period, resurface the exhaust manifold. NOTE IF THE MANIFOLD IS TO BE RESURFACED, THE BOLTS MUST BE SHORTENED TO ACCOMMODATE THE EXHAUST MANIFOLD. THE BOLTS SHOULD HAVE THE LEADING “DOG POINT” REMOVED TO PREVENT BOTTOMING INTO THE HOLE. 3. Install the manifold using new mounting hardware, but DO NOT USE WASHERS TO INSTALL THE MANIFOLD. Torque the bolts to 34-47 N.m (25- 35 lb-ft). NOTE THERE SHOULD NOT BE ANY TYPE OF GASKET USED BETWEEN THE EXHAUST MANIFOLD AND THE CYLINDER HEAD. 4. Check all exhaust system fittings loosened during repair for adequate tightness and allow engine to warm up. Recheck exhaust system for leaks and repair as required.

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Important: The front and rear sections of the cooler lines can be serviced separately. Refer to the appropriate steps when servicing individual lines. Perform the following procedure when removing the cooler lines from the quick connect fittings. 1. Pull the plastic cap back from the quick connect fining and down along the cooler line about 5 cm (2 inch) . 2. Using a bent-tip screwdriver, pull on one of the open ends of the retaining ring in order to rotate the retaining ring around the quick connect fining until the retaining ring is out of position and can be completely removed. 3. Remove the retaining ring from the quick connect fitting. 4. Discard the retaining ring. 5. Pull the cooler line straight out from the quick connect fitting. Installation Procedure Important: Do not reuse any of existing fittings if there is excessive corrosion. Do not reuse any of the existing retaining rings that were removed from the existing quick connect fittings. All retaining rings being installed must be new. Ensure the following procedures are performed when installing the new retaining rings onto the fittings.

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Tool Required J 41240 Fan Clutch Wrench Removal Procedure 1. Drain the coolant. 2. Remove the fan and shroud. 3. Remove the drive belt. 4. Using the J 41240, secure the water pump pulley and remove the water pump pulley bolts. 5. Remove the J 41240. 6. Remove the water pump pulley. 7. Loosen and remove the water pump bolts. 8. Remove the water pump. 9. Clean and inspect the water pump. 10. Discard and replace the gasket. Installation Procedure 1. Install a new water pump gasket. NOTICE: Refer to Fastener Notice in Service Precautions. See: Service Precautions\Vehicle Damage Warnings\Fastener Notice 2. Install the water pump and secure the water pump with the bolts. Tighten On the initial pass, tighten the bolts to 4 Nm (35 lb in). On the final pass, tighten the bolts to 10 Nm (89 lb in). 3. Install the water pump pulley. 4. Install the water pump pulley bolts.

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1. Disconnect front oxygen sensor connector. 2. Lift-up the Vehicle. 3. Disconnect rear oxygen sensor connector. 4. Separate center exhaust pipe from rear exhaust pipe. 5. Remove bolts which hold front exhaust pipe onto cylinder heads. 6. Remove front exhaust pipe and center exhaust pipe from hanger bracket. CAUTION: Be careful not to pull down front exhaust pipe and center exhaust pipe. 7. Separate front catalytic converter from front exhaust pipe and center exhaust pipe. INSTALLATION CAUTION: Replace gaskets with new ones. 1. Install front catalytic converter to front exhaust pipe and center exhaust pipe. Tightening Torque: 30 ±5 N.m (22.4 ±3.6 ft-lb) . 2. Install front exhaust pipe and center exhaust pipe and temporarily tighten bolt which installs center exhaust pipe to hanger bracket. 3. Tighten bolts which hold front exhaust pipe onto cylinder heads. Tightening Torque: 30 ±5 N.m (22.4 ±3.6 ft-lb) . 4. Install center exhaust pipe to rear exhaust pipe. Tightening Torque: 18 ±5 N.m (13.0 ±3.6 ft-lb) . 5. Tighten bolt which holds center exhaust pipe to hanger bracket. Tightening Torque: 35 ±5 N.m (26.0 ±3.6 ft-lb) .