Bad radiator cap can cause the following symptoms:

• Leaking radiator
• Overheating cooling system

Inspection:

• Look for a "swollen" (enlarged) radiator cap gasket. See Figure 1a and 1b.
• An enlarged radiator cap gasket can cause the cap to not vent properly. This can result in coolant loss and overheating.

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1. The Black Rubber Gasket should be smaller in diameter than the Metal Plunger under it (see Figure 2). If the Metal Plunger can be seen around the edge of the Black Rubber Gasket, and the gasket is clean without any deposits of a waxy residue or foreign material, the gasket is OK.

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2. If the Metal Plunger cannot be seen around the edge of the Black Rubber Gasket (see Figure 3), the radiator cap must be replaced.

• Thoroughly wipe out the radiator filler neck to remove any waxy residue or foreign material.
• Install a new radiator cap.

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3. If the Metal Plunger can be seen around Deposits the edge of the Black Rubber Gasket, but there are deposits of waxy residue or foreign material on the gasket or the metal retainer (see Figure 4), the radiator cap must be replaced.

• Thoroughly wipe out the radiator filler neck to remove any waxy residue or foreign material.

• Install a new radiator cap.

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