Vacuum Circuits & Switchover Valves
WARNING: This page is about a different car, the 1997 Mercedes-Benz C280 and 1997 Mercedes-Benz C230. However, it is still accessible from the selected car via links, so may be relevant.
- Disconnect all vacuum hoses from vacuum distribution block (located on right rear corner of engine compartment). Ensure Gray vacuum hose to intake manifold has no leaks.
- Apply 16-18 in. Hg of vacuum to "P" port on vacuum distribution block. See Fig 1. Ensure no vacuum leaks from vacuum distribution block. If distribution block tests okay, go to next step. If distribution block leaks, replace vacuum distribution block.
- Apply 16-18 in. Hg of vacuum to port No. 1 on vacuum distribution block. Ensure no vacuum bleeds from vacuum distribution block. If distribution block tests okay, go to next step. If distribution block leaks, replace vacuum distribution block.
- Apply 16-18 in. Hg of vacuum to port No. 4 on vacuum distribution block. See Fig 1. Ensure no vacuum leaks from vacuum distribution block. If distribution block tests okay, go to next step. If distribution block leaks, replace vacuum distribution block.
- Apply 16-18 in. Hg of vacuum to Red/Gray vacuum hose going to vacuum reservoir. Ensure no vacuum leaks. If vacuum reservoir and hose test okay, go to next step. If a leak occurs, replace vacuum hose or vacuum reservoir (located on right front fender panel/wheelwell).
- Apply 16-18 in. Hg of vacuum to Green vacuum hose going to switchover valve block. See Figure. Ensure no vacuum leaks from switchover valve block. If switchover block tests okay, go to next step. If switchover valve block leaks, replace switchover valve block.