Air Suspension Valve Block

Replacement of the air suspension valve block assembly, which controls air distribution to the air suspension system components on 1972 F-100 trucks equipped with aftermarket or dealer-installed air suspension systems.

Warnings

Tools required

Parts

• Air suspension valve block assembly × 1 — Use OEM specification or aftermarket equivalent matching original installation
• Air line fittings assortment × 1 — Use OEM specification
• Mounting bracket bolts × 1 — Use OEM specification
• Electrical connector (if solenoid-equipped) × 1 — Use OEM specification

Preparation

1. Park vehicle on level ground and engage parking brake.
2. Place wheel chocks behind front wheels.
3. Turn ignition to OFF position and remove key.
4. If system is equipped with an electric compressor, disconnect the negative battery cable.
5. Locate the air suspension compressor and turn it OFF or unplug it from power.
6. Locate all air suspension inflation valves (typically on frame rail or bumper) and completely deflate the system by depressing valve cores until no air pressure remains.
7. Raise rear of vehicle using floor jack placed under rear axle or frame, then support securely on jack stands positioned under frame rails.
8. Allow vehicle to stabilize and verify stability before working underneath.

Procedure

1. 1

   Locate valve block assembly
   Locate the air suspension valve block assembly, typically mounted to the driver-side frame rail between the cab and rear axle, or near the rear axle housing. The valve block is a manifold with multiple air line connections (usually 4 to 6 ports) and may have electrical solenoid valves attached. Inspect the mounting location and identify all connected air lines, electrical connectors, and mounting hardware.
2. 2

   Document air line configuration
   Before disconnecting anything, carefully document or photograph the air line routing and connection points. Label each air line with tape or tags indicating its destination (e.g., 'left air spring', 'right air spring', 'compressor supply', 'fill valve'). Note the orientation of the valve block and any directional markings on ports.
3. 3

   Disconnect electrical connections
   If the valve block is equipped with electric solenoid valves, disconnect the electrical connector(s). Press the locking tab and pull the connector straight off. If connectors are corroded or stuck, apply penetrating oil and use needle-nose pliers to carefully work the connector free without damaging the pins.
4. 4

   Disconnect air supply line from compressor
   Locate the main air supply line coming from the compressor to the valve block inlet port. Using the appropriate air line disconnect tool or wrench, disconnect this line first. Note that fitting type and size vary by kit (commonly 1/8" or 1/4" NPT threaded, or push-to-connect); identify your specific fittings before disconnecting. Expect residual air pressure to release. Cap or plug the compressor-side line to prevent contamination.
5. 5

   Disconnect air spring supply lines
   Disconnect the air lines running from the valve block to each air spring (typically 2 lines for dual air springs). Use the air line disconnect tool for push-to-connect fittings, or appropriate wrench for threaded NPT fittings. Residual air may escape. Leave the air spring-side lines connected to the air springs unless they are also being replaced.
6. 6

   Disconnect auxiliary lines
   Disconnect any remaining auxiliary lines, which may include a line to the inflation valve, pressure gauge line, or secondary manifold connections. Keep track of which port each line was connected to using your labels and photos.
7. 7

   Remove valve block mounting hardware
   Remove the mounting bolts or brackets securing the valve block to the frame rail. Most aftermarket installations use 2 to 4 bolts through a mounting bracket. Remove these bolts using the appropriate socket or wrench, supporting the valve block as you remove the final fastener to prevent it from falling.
8. 8

   Remove old valve block
   Carefully remove the valve block assembly from the vehicle. Inspect the mounting bracket for damage, corrosion, or elongated bolt holes. If the bracket is reusable and in good condition, clean it with parts cleaner and a wire brush. If damaged, replace it with the new valve block assembly.
9. 9

   Prepare new valve block
   Unpack the new valve block assembly and verify it matches the configuration of the original unit in terms of port count, port sizes, and mounting pattern. If the new unit has threaded NPT ports, wrap male threads with 2-3 wraps of thread sealant tape (Teflon tape), wrapping in the direction of thread engagement (clockwise when viewing the end of the fitting).
10. 10

    Install new valve block
    Position the new valve block assembly in the mounting location, aligning it with the mounting bracket and frame rail. Orient the valve block so that ports match the air line routing you documented earlier. Start all mounting bolts by hand to ensure proper thread engagement before tightening.
11. 11

    Secure mounting hardware
    Tighten the valve block mounting bolts securely using the appropriate socket or wrench. Tighten in a criss-cross pattern if multiple bolts are used to ensure even clamping force. While no specific torque specification is provided, tighten to a snug fit, being careful not to overtighten and strip threads in the mounting bracket. Consult the specific air suspension kit manufacturer's documentation for the correct mounting bolt torque, as values vary by bracket material and fastener grade.
12. 12

    Reconnect air spring supply lines
    Reconnect the air lines to the air springs output ports on the valve block, following your documentation from step 2. For push-to-connect fittings, ensure the air line is cut square and inserted fully until it clicks or seats. For threaded NPT fittings, hand-tighten first, then use a wrench to snug an additional 1 to 1.5 turns. Do not overtighten NPT fittings.
13. 13

    Reconnect compressor supply line
    Reconnect the main air supply line from the compressor to the valve block inlet port. Ensure the connection is secure and fully seated. For threaded fittings, tighten with a wrench to a snug fit.
14. 14

    Reconnect auxiliary lines and electrical connections
    Reconnect any auxiliary air lines (inflation valve, gauge lines, etc.) to their respective ports on the valve block, following your documentation. If equipped with solenoid valves, reconnect the electrical connector(s), ensuring they click into place and lock securely.
15. 15

    Secure air lines and wiring
    Verify that all air lines are routed away from hot exhaust components, sharp edges, and moving suspension parts. Use zip ties or hose clamps to secure lines to the frame rail or existing brackets at regular intervals. Ensure no air lines are kinked or pinched. Secure any wiring harnesses similarly.

Reassembly

1. Reconnect the negative battery cable if it was disconnected.
2. Turn on or plug in the air compressor.
3. Lower the vehicle from jack stands carefully, ensuring all tools and parts are clear.
4. Remove wheel chocks.

Verification

• With the vehicle on the ground, activate the air compressor and begin inflating the system through the fill valve or automatic compressor operation.
• Monitor system pressure buildup and listen for air leaks at all connections on the new valve block. A soapy water solution can be sprayed on connections to identify small leaks (bubbles will form).
• Verify that air is reaching both air springs and that the system pressurizes evenly. Typical operating pressure is 50-100 PSI depending on load.
• If equipped with electric solenoid valves, test valve operation by activating controls (dash switch or manual button) and verifying air flow to appropriate circuits.
• Check that the system maintains pressure over a 10-15 minute period with the compressor off. A slow leak may indicate a poor connection or damaged component.
• Verify the valve block mounting is secure with no movement or vibration.
• Test drive the vehicle at low speed and verify suspension operation is normal with no unusual noises or handling issues.

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