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
- The new shock or strut appears shorter than the unit removed from the vehicle.
- The left or right strut installs OK, but the other side won’t line up correctly.
- Noises After Shock/Strut Replacement: Causes.
- The strut started leaking fluid from the upper seal shortly after installation.
- Not enough stud threads visible to install or tighten the upper mounting nut.