1. Make a visual check of the cooling system.
2. Check the ground under the vehicle.

Is the coolant visible on the ground?

--

Go to Step 3

Go to Step 2

Check the cooling system for proper pressure retention. Refer to Cooling System Leak Testing .

Does the cooling system maintain the correct pressure?

103 kPa (15 psi)

Go to Step 13

Go to Step 3

Check for a leaking radiator.

Is the radiator leaking?

--

Go to Step 4

Go to Step 5

Repair or replace the radiator. Refer to Radiator Replacement .

Is the repair complete?

--

Go to Step 23

--

Check for a leaking coolant recovery reservoir tank or hose.

Is there a leak in the reservoir, or is the reservoir hose damaged?

--

Go to Step 6

Go to Step 7

Replace the coolant recovery tank or hose. Refer to Coolant Recovery Reservoir Replacement .

Is the repair complete?

--

Go to Step 23

--

Check the following hoses, pipes and hose connections for loose or damaged components:

Are any of the above hoses and/or connections loose or damaged?

--

Go to Step 8

Go to Step 9

Reseat the hoses and clamps. If necessary, replace the hose(s), pipe(s) and the clamp(s). Refer to:

Is the repair complete?

--

Go to Step 23

--

Check the thermostat housing for leakage?

Is there a leak at the thermostat housing?

--

Go to Step 10

Go to Step 11

Replace the thermostat housing gasket. If necessary, replace the thermostat housing. Refer to Engine Coolant Thermostat Replacement .

Is the repair complete?

--

Go to Step 21

--

Check for leak at the water pump mountings.

Is there a leak at the water pump?

--

Go to Step 12

Go to Step 13

Replace the water pump gasket(s). If necessary, replace the water pump. Refer to Water Pump Replacement .

Is the repair complete?

--

Go to Step 23

--

Check the radiator filler cap. Refer to Cooling System Leak Testing .

Is the radiator filler cap damaged?

--

Go to Step 14

Go to Step 15

Replace the radiator filler cap.

Is the repair complete?

--

Go to Step 23

--

Check the front and the rear heating systems for a leaking heater core.

Are one or both of the heater core leaking?

--

Go to Step 16

Go to Step 17

Replace the heater core. Refer to:

Is the repair complete?

--

Go to Step 23

--

Remove the engine oil dipstick and check the engine oil for a cloudy or milky-white appearance.

Is the engine oil cloudy or milky-white in appearance?

--

Go to Step 18

System OK

Remove each spark plug and inspect the spark plug for wetness and engine coolant on the plug. Refer to Spark Plug Visual Diagnosis in Engine Electrical.

Do any of the spark plugs show signs of wetness or engine coolant on the spark plug?

--

Go to Step 19

Go to Step 21

1. Remove the cylinder head corresponding to the spark plug. Refer to Cylinder Head Replacement in Engine Mechanical.
2. Inspect the cylinder head and the engine block for cracks. Refer to Cylinder Head Cleaning and Inspection or Engine Block Cleaning and Inspection in Engine Mechanical.
3. Inspect the cylinder head gasket for damage.

Is the cylinder head, the cylinder head gasket or the engine block cracked or damaged?

--

Go to Step 20

System OK

1. Replace or resurface the cylinder head or engine block as necessary.
2. Replace the cylinder head gasket. Refer to Cylinder Head Replacement in Engine Mechanical.

Is the repair complete?

--

Go to Step 23

--

Inspect the intake manifold gasket for leakage. Refer to Intake Manifold Replacement in Engine Mechanical.

Does the intake manifold show signs of leakage?

--

Go to Step 22

System OK

1. Tighten the intake manifold bolts to specification. Refer to Fastener Tightening Specifications in Engine Mechanical.
2. If the leak persists, replace the intake manifold gasket. Refer to Intake Manifold Replacement in Engine Mechanical.

Is the repair complete?

--

Go to Step 23

--

Check the cooling system for proper pressure retention. Refer to Cooling System Leak Testing .

Does the cooling system maintain the correct pressure?

103 kPa (15 psi)

System OK

Verify customer complaint. Begin diagnosis again. Go to Step 1