Step  | Action  | Yes  | No  | 
|---|---|---|---|
1  | Did you review the Symptom - Engine Cooling diagnostic information and perform the necessary inspections?  | Go to Step 2  | |
2  | Verify that the engine does not reach normal operating temperature. Does the engine reach normal operating temperature?  | System OK  | Go to Step 3  | 
3  | Inspect the coolant level. Is the coolant level below the add mark?  | Go to Step 4  | Go to Step 5  | 
4  | 
 Does the cooling system hold pressure?  | System OK  | Go to Step 5  | 
5  | Inspect for a stuck open, missing, or incorrect thermostat. Refer to Thermostat Diagnosis . Is the thermostat operating properly?  | Go to Step 6  | Go to Step 8  | 
6  | Is the vehicle equipped with a 6.6L, 7.2L or 7.8L diesel engine?  | Go to Step 7  | Go to Step 8  | 
7  | Inspect for a faulty turbocharger coolant bypass valve. Is the turbocharger coolant bypass valve functioning properly?  | --  | Go to Step 9  | 
8  | Install the correct replacement thermostat. Refer to Engine Coolant Thermostat Replacement . Is the repair complete?  | Go to Step 10  | --  | 
9  | Install a new turbocharger coolant bypass valve. Refer to Turbocharger Coolant Bypass Valve Replacement . Is the repair complete?  | Go to Step 10  | --  | 
10  | Run the engine in order to verify the repair. Does the engine fail to reach normal operating temperature?  | --  | System OK  |