2000 Caravan NOT Overheating?

The cap does three things:

  1. it allows the cooling system to pressurize to a set point, typically 16psi, to allow the coolant to get hotter without boiling. Fluid under pressure has a higher boiling point.

  2. it allows excess pressure to push the coolant into the reservoir without exposing the system to the outside world.

  3. it allows the engine as it cools to draw coolant back into the engine rather than air.

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