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Vauxhall Astra J11 · Engine
11 · Engine

Thermostat Diagnosis - 1.4L LDD and LUJ

Make
Vauxhall
Model
Astra J
Section
Engine Cooling › Other Information › Thermostat Diagnosis - 1.4L LDD and LUJ
EngineThermostat Diagnosis - 1.4L LDD and LUJ

Thermostat Diagnosis (1.4L LDD and LUJ)



Step
Action
Values
Yes
No

1
1. Pressure test the cooling system and the cap for leaks.
2. Repair any leaks before proceeding. These engines use a 105°C (221°F) thermostat. The ambient temperatures should be within the specified range given.
3. Set the HVAC controls in the OFF position.
4. Run the cold engine at idle 20°C-21°C (68-70°F) for 15-20 minutes before checking the engine temperature.
5. Check the engine coolant temperature at idle with the scan tool.

Is the engine coolant temperature (ECT) between 105-120°C (221-248°F)?
13-38°C (55-100°F)
System OK
Go to Step 2

2
Is the ECT below 105°C (221°F)?
-
Go to Step 3
Go to Step 4

3
The thermostat is opening early, or the thermostat seal is leaking.

Replace the thermostat and the thermostat seal.

Is the repair complete?
-
System OK
-

4
Is the ECT over 120°C (248°F)?
-
Go to Step 5
-

5
Is the radiator inlet hot?
-
Go to Step 6
Go to Step 7

6
1. Turn ON the heater.
2. Check if hot air is coming from the heater outlets.

Is the air hot?
-
Go to Step 11
Go to Step 12

7
There may be air in the system.

1. Add coolant to the surge tank if the coolant level is low. Refer to . Cooling System Draining and Filling
2. Recheck the radiator inlet hose.

Is the inlet hose hot?
-
Go to Step 6
Go to Step 8

8
Inspect for blockage in the following areas:

•  The cylinder head
•  The radiator
•  The radiator hoses

Is there a blockage?
-
Go to Step 9
Go to Step 10

9
1. Repair the blockage.
2. Recheck the coolant temperature with the scan tool.

Is the repair complete?
-
System OK
-

10
1. Replace the thermostat housing. Refer to . Engine Coolant Thermostat Housing Replacement
2. Recheck the coolant temperature with the scan tool.

Is the repair complete?
-
System OK
-

11
Inspect for blockage in the radiator.

Is there any blockage?
-
Go to Step 9
Go to Step 10

12
1. Accelerate the engine several times in order to remove any air from the system.
2. Inspect for blockage in the heater circuit.
3. Inspect for any pinched or buckled hoses.

Is there any blockage?
-
Go to Step 9
Go to Step 13

13
Is the repair complete?

System OK
-
 

Parts & tools for this job For Vauxhall Astra

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