Official Site · American O.E.M. Parts Company
Category 03 of 12

Cooling System

Water pumps, radiators, fan clutches, thermostats and expansion tanks to General Motors original specification for Chevrolet, GMC, Cadillac, Buick and Hummer.

Cooling is the system where a cheap substitution costs the most. A thermostat that opens a few degrees early keeps the engine below its designed operating temperature, which the engine control module compensates for with a richer mixture, higher fuel consumption and accelerated bore wear. A water pump with a different impeller vane count moves a different volume at the same engine speed. We supply cooling components to the original GM specification, including the correct thermostat opening temperature and fan clutch engagement point for the platform.

How the cooling system circulates

1 Engine Block heat generated 2 Water Pump belt driven 3 Thermostat opens at spec temp 4 Radiator heat rejected 5 Cooling Fan airflow on demand CLOSED LOOP
Schematic view — component order shown for orientation. Not a model-specific engineering drawing.

Coolant leaves the block, is driven by the pump, passes the thermostat once it reaches its rated opening temperature, sheds heat in the radiator with fan assistance, and returns to the block.

What we supply in this category

Symptoms that point to this system

Common complaints

  • Temperature gauge climbing under load or while towing
  • Coolant loss with no visible external leak
  • A sweet odour or white residue around the pump weep hole
  • The engine taking an unusually long time to reach operating temperature
  • Cooling fan roar that never subsides, or a fan that never engages

Before you order

Always replace the thermostat with the original opening temperature. Fitting a cooler-rated thermostat to cure an overheat masks the real fault and pushes the engine out of its closed-loop fuelling target permanently.

Vehicle coverage

We supply Cooling System components across every General Motors division:

Questions we are asked about Cooling System

Should the water pump be changed with the timing components?

On engines where the pump is driven by the timing chain or belt, yes. The labour to reach it is nearly all of the job, and a pump that fails a year later means paying that labour twice.

Why does my engine overheat only when towing?

Sustained high load exposes marginal capacity that is invisible in normal driving. The usual causes are a fan clutch that no longer locks up, a radiator core partially blocked internally, or a thermostat that opens fully but late.

Need this part identified?

Send the VIN and a description. We will identify the correct OE part and quote it back to you.

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