The main reason that shocks or struts leak is that the upper seals wear or become damaged causing hydraulic fluid to leak out of the top. Actually, vehicle use rarely causes leaks. There are several things that can cause seal wear; including:
- Dirt and debris getting inside of the shock/strut:This often happens when the strut boot is torn or not sealed properly
- A damaged strut shaft: If there is any damage, pitting or scoring on the polished shaft it will cause premature or rapid wear on the upper seals. It is critical not to use pliers on the polished shaft during installation as this can damage the shaft.
More Technical Tips
- Over-tightening the upper strut shaft mounting nut causes damage.
- The strut started leaking fluid from the upper seal shortly after installation.
- Does any fluid need to be put into the strut housing when replacing a cartridge-style strut?
- The supplied small parts kit has too many or not all of the parts needed.
- The original mounting stud nut does not thread correctly or damages the new KYB shock/strut upper mounting stud threads.