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 MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 904 (ENGINE COOLING SYSTEM)REPAIR INSTRUCTIONSWATER PUMP REPLACEMENT (4.3L)INSTALLATION PROCEDURE

2003 Chevrolet TrailBlazer 4.2 S, 4WD

Installation Procedure

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Installation Procedure

WARNING: This page is about a different car, the 2003 GMC Sonoma, 2003 GMC Jimmy, 2003 Chevrolet S10 Pickup, and 2003 Chevrolet Blazer. However, it is still accessible from the selected car via links, so may be relevant.

Install the water pump gaskets.

Fig 1: Installing Water Pump Gaskets
Courtesy of GENERAL MOTORS CORP.
Install the water pump to the engine.

Fig 2: Installing Water Pump To Engine
Courtesy of GENERAL MOTORS CORP.
Apply a sealer (GM P/N 12346004) to the bolt threads.
NOTE: Refer to FASTENER NOTICE in Cautions and Notices.
Install the water pump mounting bolts.
Tighten

Tighten the mounting bolts to 41 N.m (30 lb ft).

Fig 3: Installing Water Pump Mounting Bolts
Courtesy of GENERAL MOTORS CORP.
Install the radiator outlet hose to the water pump.

Fig 4: Installing Radiator Outlet Hose
Courtesy of GENERAL MOTORS CORP.
Install the water pump pulley.
Install the water pump pulley bolts.
Tighten

Tighten the water pump pulley bolts to 25 N.m (18 lb ft).
Install the drive belt. Refer to DRIVE BELT REPLACEMENT in Engine Mechanical - 4.3L.
Install the fan clutch assembly. Refer to FAN CLUTCH REPLACEMENT .
Fill the radiator cooling system. Refer to DRAINING AND FILLING COOLING SYSTEM .
Inspect the cooling system for leaks.

Fig 5: Installing Water Pump Pulley
Courtesy of GENERAL MOTORS CORP.

RENDER: 1.0x

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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.