Cooling system, checking for leaks

WARNING: This page is about a different car, the 2009 Audi A4, 2008 Audi A4, 2007 Audi A4, 2006 Audi A4, and 2005 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Special Tools - Cooling System, Checking For Leaks

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Special tools, testers and auxiliary items required

Cooling system tester V.A.G 1274
Adapter V.A.G 1274/8
Adapter V.A.G 1274/9

Work procedure

Engine at operating temperature.

CAUTION: Cover cap of expansion tank with rag and open carefully, as hot steam i.e. hot coolant may escape when opening.

Open cap of coolant expansion tank.

Fig 2: Positioning Cooling System Tester V.A.G 1274 With Adapter V.A.G 1274/8 On Expansion Tank

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Position cooling system tester V.A.G 1274 with adapter V.A.G 1274/8 on expansion tank.
Generate a positive pressure of approx. 1.0 bar using hand pump of cooling system tester.

If pressure drops:

Search for leaking areas and repair malfunction.

Pressure relief valve in cap, checking

Fig 3: Checking Pressure Relief Valve In Filler Cap

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Position cooling system tester V.A.G 1274 with adapter V.A.G 1274/9 on cap.
Generate a positive pressure using hand pump of cooling system tester.

Pressure release valve must open at a positive pressure of 1.4 to 1.6 bar.

If check-valve does not open as indicated:

Replace cap.