SHOCK & Strut LEAKS
Myths, truths and causes: The subject of leaks has caused more controversy than most any other vehicle component. Is a small leak still too much? Does any leak at all mean that the shock or strut needs to be replaced? Is it always the shock’s fault?
So here’s our opportunity to set the record straight and help you become the expert. First of all, shocks & struts are designed to leak! (a little) Actually, we don’t consider a hydraulic stain a “leak” at all. To keep the polished upper shaft clean and rust free KYB builds a lubricating wiper into the upper seal on all shocks & struts. As the shaft moves in and out it gets cleaned and oiled. During rapid movements a very small amount can become airborne or mist. It can settle on the top of the shock or strut body, collect dust & appear wet. Keep in mind that it only takes a few of drops to moisten the top inch or two. So, most leaks aren’t leaks at all.
Here’s an illustration of what we consider normal and abnormal. If there’s a stream down one side, if fluid covers the majority of the body or if there’s an active drip, there’s usually a problem with that damper. However, if the moisture is only at the top, it’s probably not enough to be concerned about.
The main reason that shocks and struts leak is that the upper seals wear or become damaged. Actually, vehicle use rarely causes leaks. There are several things that are far more common: Dirt and debris are abrasive. If the shaft isn’t protected with a dust cover or strut boot or if the boot has a rip or hole you can bet that this will shorten its life. Vehicles driven in areas with salted roads or dusty environments are most at risk. Nicks, scratches and pitting on the polished surface are going to cause a nearly instant seal failure.
Other causes to consider is any condition that puts excessive side pressure on the body or shaft. (wheel alignment, raised or lowered suspensions and worn or damaged suspension components are common causes)
In any case, determining if it’s time to replace shocks and struts should involve more than just looking for a leak. Vehicle performance evaluations are still the best way to help the motorist make good decisions about maintaining designed vehicle control.
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