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 593 (ENGINE COOLING SYSTEM)REPAIR INSTRUCTIONSCOOLANT BYPASS HOSE REPLACEMENTINSTALLATION 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 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.

Install the by-pass hose to the vehicle.
For vehicles with the 6.5L diesel engine, connect the by-pass hose to the water pump.

Fig 1: Installing By-Pass Hose (6.5L)
Courtesy of GENERAL MOTORS CORP.
For vehicles with the 8.1L engine, connect the by-pass hose to the water pump.

Fig 2: Connecting By-Pass Hose (8.1L)
Courtesy of GENERAL MOTORS CORP.
For vehicles with the 4.3L and 5.0/5.7L engines, connect the by-pass hose to the water pump.
Install the upper fan shroud. Refer to Fan Shroud Replacement .
Install the coolant recovery reservoir or surge tank. Refer to Coolant Recovery Reservoir Replacement or Surge Tank Replacement .
Refill the engine cooling system. Refer to Draining and Filling Cooling System .

Fig 3: Connecting By-Pass Hose (4.3L & 5.0/5.7L)
Courtesy of GENERAL MOTORS CORP.
Install the air cleaner assembly. Refer to the appropriate procedure:
- For 6.5L, refer to AIR CLEANER ASSEMBLY

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.