Diagnosis And Testing - Shock Absorber
A knocking or rattling noise from a shock absorber may be caused by movement between mounting bushings and metal brackets or attaching components. These noises can usually be stopped by tightening the attaching nuts. If the noise persists, inspect for damaged and worn bushings, and attaching components. Repair as necessary if any of these conditions exist.
A squeaking noise from the shock absorber may be caused by the hydraulic valving and may be intermittent. This condition is not repairable and the shock absorber must be replaced.
The shock absorbers are not refillable or adjustable. If a malfunction occurs, the shock absorber must be replaced.
To test a shock absorber, hold it in an upright position and force the piston in and out of the cylinder four or five times. The action throughout each stroke should be smooth and even. This procedure does not apply to load leveling shocks.
The shock absorber bushings do not require any type of lubrication. Do not attempt to stop bushing noise by lubricating them. Grease and mineral oil-base lubricants will deteriorate the bushing.
When checking the rear shock absorbers visual condition it should be noted that slight oil dampness or "misting" does not indicate the unit has failed. Below are examples of misting shocks and a failed leaking shock:
LIGHT and MEDIUM MISTING SHOCKS (DO NOT REPLACE)
HEAVY MISTING SHOCK (DO NOT REPLACE)
FAILED LEAKING SHOCK (REPLACE)