Cooling System: Testing and Inspection

Cooling System, Checking for Leaks

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

• The engine is at operating temperature

Test Sequence


Steam can be released when the cap is removed from the expansion tank. Cover the cap with a cloth and open carefully.

- 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) on 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 a positive pressure of approximately 1.0 bar using the tester hand pump.


Risk of scalding! 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.

Checking the Pressure Relief Valve in the Cap

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

- Clamp the connecting piece (V.A.G 1274 B/1) on 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.






- Actuate the hand pump.

• The pressure release valve must open at 1.4 to 1.6 bar.