Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 455 (ENGINE MECHANICAL)REPAIR INSTRUCTIONSON-VEHICLE REPAIR INSTRUCTIONSTIMING CHAIN AND SPROCKETS REPLACEMENTREMOVAL PROCEDURE

1999 GMC Forward Control 5.7 R, Automatic

Removal Procedure

1999 GMC Forward Control 5.7 R, AutomaticSECTION Removal Procedure

WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

Remove the engine front cover. Refer to ENGINE FRONT COVER REPLACEMENT .
Align the crankshaft timing mark (2) to the timing mark on the bottom of the timing chain dampener (1).
Align the timing mark on the camshaft gear (4) with the timing mark on top of the timing chain dampener (3).

Fig 1: Aligning Crankshaft And Camshaft Timing Mark With Timing Chain Dampener Marks For Removal
Courtesy of GENERAL MOTORS CORP.
Remove the camshaft sprocket bolt.
Remove the camshaft sprocket and timing chain.

Fig 2: Removing Camshaft Sprocket And Timing Chain
Courtesy of GENERAL MOTORS CORP.
Remove the crankshaft sprocket.

Fig 3: Removing Crankshaft Sprocket
Courtesy of GENERAL MOTORS CORP.
Remove the timing chain dampener bolts.
Remove the timing chain dampener.
Clean and inspect the timing chain and gears. Refer to TIMING CHAIN AND SPROCKETS CLEANING AND INSPECTION in the Engine Unit Repair Manual.

Fig 4: Removing Timing Chain Dampener
Courtesy of GENERAL MOTORS CORP.

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.