Volkswagen Workshop Service and Repair Manuals

Checking charge air system for leaks Special tools and workshop equipment required

t  Charge air system tester -V.A.G 1687-

t  Hose clip pliers -VAS 6340- t  Engine bung set -VAS 6122- (not shown) Engine cover ► November 2006

–  Release vacuum hose on vacuum reservoir -arrow- and pull it off. –  Lift engine cover panel at points -1- and pull it forwards in direction of -arrow-. Engine cover November 2006 ►

–  Pull vacuum hose off -arrow-. –  Lift engine cover panel at points -1- and pull it forwards in direction of -arrow-. –  Press hose locking mechanism and pull hose for crankcase breather -1- off intake connecting pipe. –  Also pull crankcase breather hose off valve timing housing.   Caution Crankcase breather hose must be pulled off during leak test to prevent damage to engine.

–  Seal intake connecting pipe with a bung from engine bung set -VAS 6122-. –  Remove spring-type clips -2- from intake hose and remove intake hose.

–  Renew spring-type clips -arrows- with screw-type clips from charge air system tester -V.A.G 1687-.

–  Slide adapter -V.A.G 1687/6- into intake hose -2- and secure hose to intake connecting pipe with screw-type clips -1- from charge air system tester -V.A.G 1687-. Prepare charge air system tester -V.A.G 1687- as follows:

–  Unscrew pressure regulating valve -2- and close valves -3- and -4-.

–  Connect charge air system tester -V.A.G 1687- as shown.

–  Connect pressure hose -1- (compressed air supply) to charge air system tester -V.A.G 1687-.   Note If there is water in the sight glass, drain at water drain screw -6-. –  Open valve -3-. –  Adjust pressure to 0.5 bar with pressure regulating valve -2-.   Caution The pressure must not exceed 0.5 bar! If the pressure is too high this can cause damage to the engine. –  Open valve -4- and wait until the test circuit is filled. If necessary readjust pressure to 0.5 bar. –  Check the charge air system for leaks by hearing, touching, with commercially available leak detector spray or using ultrasonic tester -V.A.G 1842-.   Note

t  Slight leaks in the area of the intake connecting pipe -arrows- are permissible, as the intake hoses are not designed for high-pressure. t  A small amount of air escapes through the valves and enters the engine. Therefore a holding pressure test is not possible. t  How to use the ultrasonic tester -V.A.G 1842- → operating instructions t  Depressurise test circuit by detaching coupling from adapter -V.A.G 1687/6- before removing adapter. t  Hose connections and hoses must be free of oil and grease before assembly. t  After testing compression, secure intake hoses again with spring-type clips. Engine cover ► November 2006

–  Place vacuum hose -2- onto vacuum reservoir union -1-.   Note Ensure that the vacuum hose is locked onto the union -2-.

–  Push engine cover panel down at points -1- in direction of -arrow- until it engages. Engine cover November 2006 ►

–  Push engine cover panel down at points -1- in direction of -arrow- until it engages. –  Fit vacuum hose onto connection -arrow-.