Table of Contents
Vacuum Box (126 270 91 79)
Removal
Installation
Adjustment
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