Struts or Shock Absorbers Bench Test

AIR-ADJUSTABLE (ELC) STRUT DAMPER
Stroke all air-adjustable strut dampers before attempting a bench check. When stored horizontally, such as new units in stock, an air pocket may develop in the pressure chamber. This pocket can also form when an air-adjustable strut is off the vehicle if it is not continuously held with the top end up.

Perform the following procedure in order to remove air from the pressure chamber:

Purge
^ Extend in vertical position, top end up.
^ Collapse in vertical position, top end down.
^ Repeat this procedure five (5) times in order to verify that the air is purged from the pressure chamber.

Bench Test
1. Clamp the strut in a vise with the strut damper upright, top end up. Do not clamp on the reservoir tube.
2. Pump the strut damper by hand at various rates of speed. Note the resistance.
3. Rebound resistance nominally is stronger than compression resistance by about 2 to 1. The resistance should be smooth and constant for each stroking rate.
4. Compare the strut damper under inspection with a strut damper known to be good.
5. It is normal to hear a hissing noise. The following symptoms are abnormal and are reason for replacement.
^ A skip or lag at reversal near mid-stroke
^ A seize (except at either extreme end of travel)
^ A noise (such as a grunt or squeal) after completing one full stroke in both directions
^ A clicking noise at fast reversal
^ Fluid leakage