Struts are rarely a safety issue on their own but they can cause excessive bouncing and reduced control when cornering. Leaking shocks in the rear is cause for replacement too but it's more of a comfort thing. The oil inside travels though a restriction as the shock absorber extends and retracts. The shock pulls apart hard to reduce the tendency of a tire to drop into a pothole, and retracts easily to allow a tire to go up over a bump without pushing the van up.
Struts can cause a bumping noise but usually not until long after the oil has leaked out. An quick inspection during routine maintenance will find this. A more involved inspection is needed to find noises. Severely worn struts can be found by placing a fingertip on the shaft while pushing and pulling on the top of the tire. The van must be on the tires; it can't be on a frame-contact hoist because a fully extended strut is the only thing holding the tire up. When fully extended, there is pressure on the strut shaft that prevents it from moving so the wear won't show up. Also, there is a rubber boot that must be moved out of the way to do this test. That can be hard to do.
Starting with the '96 model, there was a lot of trouble with inner anti-sway bar bushings making a light thumping noise. That is not a safety issue at all, just irritating. It's only heard in a parking lot or at low speeds. A clue is the noise will stop when turning the steering wheel a little in either direction. That puts the bar in a twist that puts pressure on the bushings causing the movement and thumping to stop momentarily.
Suspension and steering noises should always be checked by a professional. Chrysler has relatively little trouble with ball joints and steering linkages compared to some other manufacturers, but by 145,000 miles, parts will be wearing out. At 217,000 miles on my '88 Grand Caravan, I've only had to replace one outer tie rod end, and that's after not keeping up with oil changes and lube jobs at the recommended intervals. Quite the testament to quality. That doesn't mean parts on every vehicle will last that long.
If you hear one clunk when turning the steering wheel, suspect a worn ball joint or tie rod end. Either of these can become real serious if they separate. You might be able to make it act up by rapidly turning the steering wheel back and forth a few inches. Ball joints often clunk once when turning a corner and once again when straightening out.
If you hear multiple clunks or thumping as you turn the steering wheel from full left to full right and back again, suspect worn upper strut mounts. You can find these yourself by holding your fingers on one of the front springs while a helper turns the steering wheel. The spring and wheel assembly should rotate smoothly. If you feel the top of the spring stick as the wheel turns, then suddenly pop and turn, the upper mount has worn bearings. This also won't cause a safety problem and often doesn't happen at highway speeds because you're not turning that far and road shock allows the mount to break free and turn.
Most reputable mechanics will do a quick visual inspection during routine maintenance. That's how they found the leaking rear shock absorbers. But unless you mention the noise, they won't look for things that require a more in-depth inspection. Some shops, and particularly some of the big chain stores, offer free inspections as a way to generate potential business. They will usually be willing to show you what they found and explain what noises or safety concerns it will cause. Also be aware that replacement of struts, ball joints, and tie rod ends will necessitate an alignment. If there are no tire wear issues currently, only replacing the rear shock absorbers or any anti-sway bar links or bushings will not require an alignment.
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Wednesday, December 16th, 2009 AT 8:40 AM