Cooling System, Checking For Leaks

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Special tools and workshop equipment required

Cooling System Tester: VAG1274B
: VAG1274/8
: VAG1274B/15 , for Version 1 Cap
: VAG1274/9 for Version 2 cap
Protective Eyewear
Safety Gloves

Procedure

Test Requirements

Engine at operating temperature.
Ignition off.

WARNING:

The cooling system is under pressure when the engine is warm. 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- if necessary.

Fig 1: Coolant Expansion Tank

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Tip:

Different versions depending on models and version.

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

Courtesy of AUDI OF AMERICA, LLC

-- Generate approximately 1.0 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:

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 : VAG1274B/15 on the cap.

Courtesy of AUDI OF AMERICA, LLC

-- Generate approximately 2.0 bar (29.0 psi) pressure using the cooling system tester hand pump.

Blue Cap:

The pressure must lower to 1.6 to 1.4 bar (23.2 to 20.3 psi) and stay there.

Black Cap:

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

All Caps:

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

Checking the Pressure Relief Valve in the Version 2 Cap:

Courtesy of AUDI OF AMERICA, LLC

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

Courtesy of AUDI OF AMERICA, LLC

-- Generate approximately 2.0 bar (29 psi) pressure using the cooling system tester hand pump.

Blue Cap:

The pressure relief valve must open at a pressure of 1.4 to 1.6 bar (20.30 to 23.20 psi) and stay there.

Black Cap:

The pressure relief valve must open at a pressure of 1.6 to 1.8 bar (23.20 to 26.10 psi) and stay there.

All Caps:

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