Cooling System, Checking For Leaks

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Special tools and workshop equipment required

Cooling System Tester: VAG1274B
Cooling System Tester - Adapter: VAG1274/8
Cooling System Tester - Adapter: VAG1274/9 for version 2 cap
Adapter: VAG1274B/15 for version 1 cap

Procedure

Engine at operating temperature.
Ignition switched off.

CAUTION:

The cooling system is under pressure when the engine is warm. There is a risk of scalding due to hot steam and hot coolant.

Scalding the skin and other parts of the body is possible.

- Wear safety gloves.

- Wear protective eyewear.

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

-- Open the coolant expansion tank cap -1- by releasing the catch in direction of -arrow-.

Fig 1: Coolant Expansion Tank

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-- Position the : VAG1274B with the : VAG1274/8 on the coolant expansion tank.

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-- Generate approximately 1 bar (14.5 psi) pressure using the cooling system tester hand pump.

The pressure must not drop more than 0.2 bar (2.9 psi) within 10 minutes.

-- If the pressure falls more than 0.2 bar (2.9 psi), search for leaks and correct the problem.

TIP:

The pressure decrease of 0.2 bar (2.9 psi) within 10 minutes is a condition of the cooling of the coolant. The colder the engine the more the pressure decrease. If necessary repeat the test with the engine cold.

CAUTION:

There is a risk of scalding due to hot steam and hot coolant.

Scalding the skin and other parts of the body is possible.

- Reducing the pressure: press the pressure release valve on the cooling system tester until the pressure gauge displays a value of 0.

Checking the Pressure Relief Valve in the Version 1 cap

Fig 2: Coolant Expansion Tank

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-- Position the : VAG1274B with the : VAG1274B/15 on the cap.

-- Generate approximately 2 bar (29 psi) pressure using the cooling system tester hand pump.

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The pressure must lower to 1.8 to 1.6 bar (26.1 to 23.2 psi) and stay there.

-- If the pressure relief valve does not react as specified, replace the cap.

Checking the Pressure Relief Valve in the Version 2 Cap:

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-- Position the : VAG1274B with the : VAG1274/9 on the cap -1-.

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The pressure release valve must open at 1.6 to 1.8 bar (23.2 to 26.1 psi).

-- If the pressure relief valve does not react as specified, replace the cap.