1999 Mercedes-Benz ML320 Liftgate Support Strut Replacement Cost

A support strut is the long tube that causes the gentle hissing noise when the liftgate, hatch or hood is raised. Liftgate support struts are perhaps the most heavy duty of all of these due to the sheer weight of the liftgate which they must support. They are attached to the frame and liftgate, and when the liftgate is opened and closed, they extend and contract respectively. They hold the weight of the liftgate while opening and closing, and prevent the liftgate from falling in its raised position. These are very effective tool for ease of access to the liftgate assembly, as the assemblies tend to weigh well over 150 lbs.

Since the liftgate support strut is attached to the liftgate and the chassis of the vehicle, the support struts must be able to extend and retract without bending or breaking away from the mounts. Also, due to the weight of the liftgate, they must be able to hold weight, yet be balanced enough to allow the average person to pull the liftgate down. For these purposes. the part was designed as a very small shock absorber. Filled with inert gas or hydraulic fluid, this strut (or shock) is always attempting to extend itself. Internal pressures push two rods against each other, and one is mounted inside the other one. This causes the liftgate to be very easy to lift, as the support struts are doing most of the work. however, the liftgate struts cannot be too strong. They must only have enough force to push the liftgate open, with the addition of a few additional pounds amount of pushing force. This prevents the liftgate from falling when the wind blows, or if someone bumps it while it is open. When the liftgate is closed, one half of the strut will slide back into the other half, being forced by the user placing constant pressure on the liftgate until it is closed.

We have all noticed an old car with a stick holding up the hood or hatch. That is because the owner has not replaced the support strut for that component. Also, if you have ever tried opening a liftgate or hatch, and the support strut had failed, you would know immediately as the entire weight of the hatch would be resisting the lifting action. Also, the end of one of these liftgate support rods may be rattling around while driving, and opening the liftgate may show it is swinging freely, or falls off completely. When they separate from their mounting points, this is sure to happen.

There is nothing like a properly operating vehicle, especially when all of the accessories function, like the liftgate. zon the other hand, a heavy liftgate can make getting the groceries out of the cargo area a daunting task. Replacing these struts is not a necessary endeavour, but it can certainly add to the quality of life of the owner of the vehicle. Fix this one at your convenience, or when you are tired of dealing with the liftgate.

These fail quite often. In fact, many luxury vehicles list inspection or replacement of the liftgate struts as soon as 60,000 miles or 5 years. The rate of failure should not be this quick, but with lots of use of the liftgate, they may fail even faster. More typically, vehicles should be able to use the same liftgate struts for much longer, maybe even twice as long.

Anyone can diagnose these struts without any prior knowledge of how the part functions. All that is needed to know is that they hold the liftgate up securely. When they fail to keep the liftgate up unless it is pulled down to the closed position, it is time to replace them. Also, if the liftgate support struts are able to rattle against their mounting points, they will likely need replacement due to this condition. This will prevent wear from allowing the strut to separate from the mounting point.

For nearly all liftgate support struts the replacement procedure is the same, and takes less than one minute. Some will require the removal of a fastener of some type, but most require the removal of a flat spring which is curved around the assembly. The flat spring will be located on the ball at the end of the strut, and using a screwdriver ror pick, the spring can be gently pulled back, which causes it to release the circular mounting point inside the ball. Once done, the strut pulls off, so ensure the liftgate has secondary support already in place. A broom handle does a very nice job of this at home. The new strut will pop right on without pulling the spring back, and the other end must be replaced in the same way. Ensure they are replaced as a set.

Never replace only one support strut, unless it was physically damaged by an external force. When one fails, the other must do every bit of the work for both, so replacing one will cause undue stress on the new one. The old, worn out strut will fail more quickly, and the new strut will wear twice as fast. This will lead to early replacement of three struts instead of two.

When the liftgate support struts are worn out, no one should not be allowed to stand between the liftgate and rear bumper, especially if the existing liftgate support struts can be made to stay in the opened position after a few tries. The slightest wind or jarring of the vehicle can cause the liftgate to swing down violently and crush anyone in its path. The use of a prop rod, like a strong piece of wood or a broom handle, is necessary if there will be loading or unloading done. Also, there should be someone there to hold the liftgate just in case. The weight of the liftgate is very much heavier than it seems with working support rods.

This is a simple fix for any DIYer, or just someone who does not want to spend money at the shop. With the most basic tool, a helper to hold the liftgate, and a few minutes, anyone can easily perform this task. Be aware, however, that the struts can be hard to compress once they are freed of their manufacturer packaging straps, as they are packed compressed and will extend forcefully when the straps are cut/removed.