Check the coolant level.

Is the coolant level low?

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Go to Step 2

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1. Check the gasket and the seal under the pressure cap.
2. Check to be sure that the cap attaches tightly to the radiator neck.

Is the pressure cap OK?

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Go to Step 4

Go to Step 3

Replace the pressure cap.

Is the repair complete?

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Go to Step 4

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1. Perform a visual check of the cooling system.
2. Check the hoses, the clamps, the radiator, the coolant pump, the thermostat housing, the radiator drain and the core plugs for signs of leaks.

Are any of these parts leaking?

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Go to Step 6

Go to Step 5

Repair the leaks found during the visual check of the hoses, the clamps, the radiator, the coolant pump, the thermostat housing, the radiator drain and the core plugs.

Is the repair complete?

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Go to Step 6

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1. Continue with the visual check of the cooling system.
2. Start the engine. Leave the pressure cap off.
3. Watch the coolant in the filler neck for signs of foaming, which indicates that air is entering the cooling system somewhere.

Is the coolant free of evidence of foaming?

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Go to Step 8

Go to Step 7

1. Look for places where air can enter the cooling system.
2. Tighten, shift, or replace parts as necessary.

Have the air leaks been repaired?

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Go to Step 8

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Check the overflow bottles, the filler neck nipple and the hose in between the radiator and the overflow bottle for obstructions.

Have all the obstructions been repaired?

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Go to Step 9

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1. Install a pressure checker on the radiator filler neck.
2. Apply the amount of pressure for which the cap is rated.
3. Watch the pressure gauge.
4. The reading should be steady. If it drops, there is a leak somewhere in the system.

Does the pressure gauge drop, indicating a leak?

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Go to Step 10

System OK

1. Look for evidence of leakage, obstructions, kinks, etc.
2. Check the hoses, the clamps, the radiator, the coolant pump, the thermostat housing, the radiator drain and the core plugs for signs of leaks.
3. Start the engine. Leave the pressure cap off.
4. Watch the coolant in the filler neck for signs of foaming, which indicates that air is entering the cooling system somewhere.
5. Check the overflow bottles, the filler neck nipple and the hose in between the radiator and the overflow bottle for obstructions.
6. Install a pressure checker on the radiator filler neck.
7. Apply the amount of pressure for which the cap is rated.
8. Watch the pressure gauge.
9. The reading should be steady. If it drops, there is a leak somewhere in the system.

Are all the checks and test completed?

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System OK

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