Need car parts? Select your vehicle
Reading Time: 5 minutes
Summary
  • Shock absorbers use a piston and hydraulic fluid to create resistance against the up-and-down movement of your vehicle as it goes over various bumps on the road.
  • Leaking shocks are caused by a damaged piston shaft, bad shock seals, worn chrome coating, oil mist residue, and regular wear and tear.
  • A suspension leak will lead to a bumpy ride for you on the road and can even compromise your safety.

Shock absorbers are an essential part of your vehicle’s suspension system. They’re there to keep your drive as smooth as possible as you cruise down roads or along trails. If your shock absorbers start leaking though, you’re in for quite a bit of trouble.

How Shock Absorbers Work

Shock absorbers, also known as dampers, create resistance against the up-and-down movement of your vehicle as it goes over various bumps on the road. By controlling this motion, it dampens the energy in your suspension’s springs, converting the kinetic energy into thermal energy. When the energy is converted into heat instead of motion, you’re left with a smoother ride.

Mechanically, the shocks have three main parts–the body, the rod (or shaft), and the piston assembly, which includes the valve system suspended in hydraulic fluid. The piston and valve assembly are typically connected to the rod, but they can also connect to the shock’s body.

See also  Best Truck Upgrades

The valve assembly uses the hydraulic fluid to dampen and control the motion of the vehicle’s suspension. It creates resistance to the motion of the rod specifically. This resistance is what converts the kinetic energy into heat. The fluid in the shocks absorbs the heat, which eventually moves to the shock body, where it can freely dissipate into the air.

diagram of shock absorbers
Diagram of shock absorbers | Image Source: Richard McCuistian

The Causes Behind Leaking Shocks

If your shocks are leaking fluid, they could be less efficient at both dampening jolts and heat dissipation.

, What Causes Leaking Shocks?

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: Shocks can fail internally but never leak externally. Failed shocks don’t dampen spring oscillations. This means that when you go over a bump, the end of the vehicle with failed shocks will continue to bounce rather than just go over the bump like it should.

rear shock absorber from a ford expedition started leaking
This rear shock absorber from a Ford Expedition started leaking as soon as the vehicle was raised on a lift but had never leaked before, and had to be replaced. | Image Source: Richard McCuistian

Generally, if there’s a leak, you’ll notice decreased performance in your shocks, leading to a bumpier ride, unusual noises, irregular tire wear, and reduced handling and braking ability. Alternatively, you might be mistaking natural shock operations for a leak.

The following are some causes that can lead to your shocks leaking, whether as a result of damage or as part of their shock-absorbing process:

See also  Loaded vs. Unloaded Strut: What’s the Difference?

Oil Mist Residue

Oil mist residue is a perfectly natural part of your shocks operating as designed. It mostly appears on very dry shocks because you won’t notice it otherwise. Oil mist occurs when the piston rod spreads a very small amount of oil from the cylinder onto the seal. The rod appears damp, but it won’t feel wet if you touch it.

However, if you see oil mist that is coming from inside the shock, you can’t add oil. In this case, you must replace the shock and it’s best to replace them in pairs (both front or both rear).

If you see oil mist that is coming from inside the shock, you can’t add oil. In this case, you must replace the shock and it’s best to replace them in pairs.

Richard McCuistian, ASE Certified Master Automobile Technician
mist on the shock body
If you see mist on the shock body such as what’s shown in the photo, replace the shock and the one on the opposite side as well. | Image Source: Richard McCuistian

Damaged Piston Shaft

A damaged shaft can lead to leaking shock fluid. When the shaft has scratches or other damage, it can tear the seal, which leads to oil loss and reduced performance. These scratches and dents can come from flying pieces of debris scratching the surface or from the shaft being improperly installed.

Bad Shock Seals

Shock seals block the inside of your shocks from the dirt and grime of the outside world. Over time, seals may become brittle and get torn easily. Rocks, gravel, and other debris can also damage your shock seals, leading to an eventual leak.

See also  What is a Torsion Key Lift?

Worn Chrome Coating

Your car shocks might be leaking because the coating on one of the piston rods is worn down. If the damper isn’t aligned properly, the coating is rubbed away. The shock seal and piston rod guide then sustain more damage as the misaligned damper continues to operate. Once these parts wear down, the shocks will leak

Wear and Tear

General wear and tear will eventually lead to front and rear leaking shocks. Your shocks go through a lot of abuse and will eventually leak and need replacing.

When To Schedule Shock Maintenance

Because the shocks are an important part of your vehicle’s suspension, you should have regularly scheduled maintenance checks even before any problems start to show up. Generally, it’s a good idea to have these inspections every 50,000 miles.

If your shocks are unusually bouncy, it’s time to get them checked by a technician.

You can also watch this tutorial video on how to replace the rear shocks of your 2009-2018 Dodge Ram 1500:

Price of Replacement Shocks

A suspension leak will lead to a bumpy ride for you on the road and can even compromise your safety. If your car struts or shocks are leaking, it’s best to have them replaced as soon as possible. Replacement parts will run you anywhere from $10 to $3,800.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

File Under : Suspension , DIY Tagged With :
get 10% off everything
Subscribe
Notify of
guest
0 Comments
Inline Feedbacks
View all comments

View all Questions & Answers

expand_more
CarParts.com Answers BE PART OF OUR COMMUNITY: Share your knowledge & help fellow drivers Join Now
Copyright ©2023 CarParts.com, Inc. All Rights Reserved.