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Replace thermostat Chevrolet Avalanche

How to replace thermostat Chevrolet Avalanche — 2003 with 5.3L VIN T engine

Replace thermostat Chevrolet Avalanche

These step by step instructions show explain how to replace thermostat Chevrolet Avalanche 2003 with the 5.3L VIN T engine

Purchase a new thermostat

My personal preference is genuine GM or STANT. I am not a fan of the cheverolet avalanche thermostatMurray Fail Safe products. I’ve had too many falsely fail in the full open position requiring replacement.

Drain the cooling system

Don’t try to drain the cooling system using the petcock on the radiator. These are plastic units that almost always break when you open them. If you’re lucky enough and yours doesn’t break, then it’ll most likely leak when you close it.

Instead, remove the hose clamp on the lower radiator hose and remove the hose. Let the coolant drain into a properly sized drain pan.

Radiator and heater hose removal tools

Remove the upper radiator hose clamp and hose at the water outlet

Use a hose spring compressor tool to remove tension from the hose clamp. Slide the hose clamp up on the hose so it’s out of the way. Then remove the hose and position it out of the way.

Remove the thermostat housing

Remove the three bolts holding the thermostat housing to the water outlet assembly.

avalanche thermostat

Thermostat housing

Then remove the thermostat

The new thermostat should come with a new rubber O-ring. Do NOT install the thermostat without a new O-ring and don’t re-use the old O-ring.

Install the new thermostat

Install a new thermostat on Chevrolet Avalanche water outlet housing with the pellet section of the thermostat facing down into the water outlet assembly.

chevrolet avalanche thermostat

Thermostat pellet facing into engine


Place the thermostat housing over the thermostat and install the three hold-down bolts. Torque to 11/lb-ft. Do NOT overtighten!!

Refill cooling system and bleed air

©, Rick Muscoplat


Posted on by Rick Muscoplat

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