Rear Suspension

Air Suspension Strut

If shock absorbers leak, replace suspension strut (air suspension) completely because shock absorber oil can damage the boot - item 4 - => [ (Item 4) Boot ] Air Suspension Strut Components.

Suspension strut (air suspension) must not be rotated when it is not pressurized. There is the danger that the boot inside the suspension strut (air suspension) could be damaged by kinking or folding.

For problem-free and successful suspension strut (air suspension) repairs, the greatest care and cleanliness possible and tools that function properly are important requirements. Understandably, general safety guidelines apply when performing repairs.

A series of applicable general notes for individual repair procedures - otherwise listed several times at many points in the repair manual - has been collected here. They apply to suspension strut (air suspension) repairs.

Suspension Strut (air suspension)






- Before loosening air line when installed, check, whether air spring is still filled with a residual pressure of approximately 3 bar.

- Press with thumbs on air spring boot. Boot must demonstrate noticeable resistance.

- If great resistance is not noticed, air spring is not pressurized and it must be replaced together with the residual pressure retaining valve.

• Thoroughly clean connecting points and their surrounding areas before loosening.

• To install suspension strut (air suspension), it must be filled with argon or corgon. Refer to => [ Air Suspension Strut, Filling ] Rear Suspension.

• Place removed parts on a clean surface and cover to prevent contamination. Use foils and paper. Only use lint-free cloths!

• Only install clean components: Only unpack replacement parts immediately prior to installation.

• Only use lubricants indicated by replacement part number.

• Carefully cover or seal open components, if repairs are not carried out immediately.

Residual Pressure Retaining Valve

Residual pressure valve may only be replaced if:

• Damaged during removal and installation or servicing of suspension strut (air suspension),

• Residual pressure retaining valve stuck,

• Gasket is faulty.

If residual pressure retaining valve sticks, the vehicle must be on a hoist and the wheels must rotate freely in order to replace the valve. Wheels must not be compressed with empty boot under any circumstances!

Seals, Sealing Rings

Always replace gaskets and boot.

After removing seals, check sealing surfaces on housings for burrs and damage.

Bolts and Nuts

• Loosen and tighten the bolts and nuts of covers and housings in a diagonal sequence.






• Tightening specifications for unlubricated bolts and nuts are given.