Shock Absorbers: Inspection

On hydraulic fluid filled shock absorber (spiral-groove reservoir), check for binding, excessive noise, missing bump stops, worn or damaged rubber mounting grommets and hydraulic fluid leaks around seal cover area.
NOTE: A slight trace of hydraulic fluid (Dark Brown tint with a characteristic odor) around seal cover area is not a cause for replacement.

CAUTION: Ensure all hydraulic shocks that have been stored horizontally are purged of air before inspection or misdiagnosis may result. See step 5).
Check shock for proper dampening and internal noise by stroking unit (with top of shock held vertical) through full rebound (up) and compression (down). Movement should be smooth and consistent with the most resistance (by approximately 2:1) during extension.
If shock has an internal noise, check for loose piston by extending shock fully, then exert an extra pull. If noisy, shock should be replaced. Also replace shock if a squeal or grunt is heard after one full stroke in both directions, a clicking noise on fast reverse, or a skip or lag at reversal near midstroke.
On gas-charged shock absorber (smooth-bodied reservoir), ensure bench checking is done with shock inverted (top end down). If, when stroked, a lag is noticed, it indicates that the gas-filled cell is ruptured and shock should be replaced. If no lag is noticed, continue to check unit by following steps 1) through 3) for hydraulic shocks.
Purge shock by mounting unit in vise (with top in vertical position), then fully extend shock. Next, hold top of shock down and fully collapse unit. Repeat procedure several times to purge air void. After purging air, clamp lower shock mounting ring vertically in vise (large diameter tube up). Pump unit by hand at different rates of speed.
Smooth resistance should be felt through the length of the stroke. Since unit is normally pressurized, the sound of air bubbles or a gurgling noise is normal. To complete inspection, continue to check unit by following steps 1) through 3) for hydraulic shocks.