LEVELING VALVES

Leveling Valves For Peterbilt Trucks

Leveling valves — also called height control valves — automatically maintain a consistent ride height on air suspension-equipped Peterbilt trucks by adding or exhausting air from the suspension air bags in response to load changes. When a leveling valve fails or drifts out of calibration, the truck may ride too high, too low, or at uneven heights side to side, affecting handling, fifth wheel height, trailer coupling, and air bag service life. We carry replacement leveling valves and related air suspension hardware for Peterbilt trucks.

Frequently asked questions about leveling valves

What are the symptoms of a failed leveling valve on a Peterbilt?

A failed leveling valve typically causes the suspension to ride at an incorrect height — either too high with the valve stuck open, or too low with the valve stuck closed or leaking. A valve that's hunting or oscillating continuously, adding and releasing air without settling, indicates a valve that's out of calibration or has a failed internal mechanism. Uneven side-to-side ride height, where one side of the suspension is noticeably higher than the other, usually points to a single failed valve in a dual-valve system.

How is a leveling valve adjusted on a Peterbilt air suspension?

Leveling valve adjustment is made by changing the effective length of the linkage arm connecting the valve to the axle — shortening the link raises the ride height set point, lengthening it lowers it. The correct ride height specification for your Peterbilt's suspension system is found in the suspension manufacturer's service manual and must be measured with the truck on a level surface under its rated load. Improper adjustment affects fifth wheel height, trailer coupling angle, and can overload or underload the air bags.

Can a leveling valve be repaired, or does it need to be replaced?

Most leveling valves are not field-serviceable at the internal component level — when the valve mechanism fails, replacement is the standard repair. Some manufacturers offer rebuild kits for specific valve models, but given the low cost of replacement valves relative to the labor involved, most shops opt for outright replacement. Always replace the valve linkage hardware and check the linkage geometry during replacement to ensure the new valve is set to the correct ride height specification.

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