Vacuum Box (126 270 91 79)
Vacuum Box (126 270 91 79)
Vacuum box that controls modulating pressure based on engine load
Part number(s): 126 270 91 79
Used on: 722.3, 722.4, 722.5
Removal
- Locate vacuum modulator on left side of transmission
- Unplug vacuum line from intake manifold
- Remove 2x 5mm allen screws holding bracket to transmission case
- Pull vacuum modulator out or pry gently with screwdriver
Loosening screws on vacuum modulator
Old vacuum modulator removed
Installation
- Clean the surface area on transmission case where vacuum modulator is installed
- Assemble vacuum modulator pieces
- Thrust pin
- Turn key and cap
- Mounting bracket
- O-ring
- Insert vacuum modulator assembly
- Tighten 2x 5mm allen screws
- Reattach vacuum line from intake manifold
- Replace old vacuum line parts if necessary
- 117 997 09 82 - Rubber vacuum connector
- 117 078 05 81 - Vacuum elbow
- 116 276 06 30 - Plastic vacuum line (black)
Clean vacuum modulator mating surface
New vacuum modulator installed
Adjustment
- Disconnect vacuum line from modulator
- Plug the intake manifold line to prevent leak during testing
- Locate tester port near bottom right of vacuum modulator on transmission case. Remove 12mm hex screw cover.
- Thread pitch for this hole is M8x1.0. Use an engine oil pressure tester kit and connect the gauge to this port.
- Drive vehicle at 30mph with selector in D and read pressure value off gauge
- Although the proper procedure is to perform measurements while car is moving, the same pressure could be measured by idling in D at a complete stop.
- Adjust pressure by removing the turn key cap and turning the key clockwise or counter-clockwise
- Clockwise rotation increases pressure by approximately 6psi
- Counter-clockwise rotation decreases pressure by approximately 6psi
- When complete, remove testing gauges and reconnect vacuum line
Engine oil pressure test kit
Adapter we need for testing port.
Pressure testing kit hooked up with an elbow piece
Achieving 58psi @ 30mph