Cooling System: Testing and Inspection

Cooling System, Checking for Leaks

=> [ Pressure Relief Valve in Cap, Checking ]

Special tools, testers and auxiliary items required

• Cooling System Tester (V.A.G 1274 B)

• Adapter (V.A.G 1274/8)

• Adapter (V.A.G 1274/9)

Test Conditions

• Engine is at operating temperature

Test Sequence


Risk of scalding due to hot steam and hot coolant:

• When the engine is warm the coolant system is under pressure.

• Wear protective goggles and protective clothing to prevent damage to eyes and scalding.

• Reduce pressure by covering the coolant expansion tank cap with a cloth and carefully opening.

- Open the cap on the coolant expansion tank.

- Install the adapter (V.A.G 1274/8) onto the coolant expansion tank.

- Clamp the connecting piece (V.A.G 1274 B/1) to the adapter (V.A.G 1274/8).

- Connect the connector piece (V.A.G 1274 B/1) to the cooling system tester (V.A.G 1274 B) using the connecting hose.

- Generate approximately 1 bar pressure using the cooling system tester (V.A.G 1274 B).


Risk of scalding due to hot steam and hot coolant:

• Reduce the pressure before disconnecting the cooling system tester (V.A.G 1274 B) from the connecting hose or connector piece (V.A.G 1274 B/1).

• To do this, press the pressure release valve on the cooling system tester (V.A.G 1274 B) until the pressure gauge displays "0".

If the pressure drops:

- Look for leaks and correct.

Pressure Relief Valve in Cap, Checking


Risk of scalding due to hot steam and hot coolant:

• When the engine is warm the coolant system is under pressure.

• Wear protective goggles and protective clothing to prevent damage to eyes and scalding.

• Reduce pressure by covering the coolant expansion tank cap with a cloth and carefully opening.

- Open the cap on the coolant expansion tank.

- Install the cap in the adapter (V.A.G 1274/9).

- Clamp the connecting piece (V.A.G 1274 B/1) to the adapter (V.A.G 1274/9).

- Connect the connector piece (V.A.G 1274 B/1) to the cooling system tester (V.A.G 1274 B) using the connecting hose.

- Generate a maximum pressure of 1.6 bar using the cooling system tester (V.A.G 1274 B).

• Pressure relief valve must not open yet.

If the pressure relief valve opens prematurely:

- Replace the cap.

- Increase the pressure to above 1.6 bar.

• Pressure relief valve must open.

If the pressure relief valve does not open:

- Replace the cap.