The tonneau cylinder lifts the storage cover and it is mounted in the middle under the storage cover - it is typically the first one to fail in the Mitsubishi Eclipse.

P/N: MN181812

We use the best seals available, far exceeding OEM quality. Top Hydraulics' rebuilt cylinders will not be as pretty on the outside as brand new ones, but the inside is far superior due to the seals we use.

Mitsubishi part number MN181812, shown as part of PNC Part Spec 78146D in Mitsubishi parts diagrams
The engravings on the cylinder housing are not the Mitsubishi part number. You can, however, identify the part as follows: the middle line of engravings typically reads 2006-030-A or 2006-030-B or 2006-030-C

The hydraulic cylinders are connected to the hydraulic pump via hydraulic hoses. Top Hydraulics manufactures new hydraulic hoses out of superior material, and Top Hydraulics can rebuild your Eclipse folding top hydraulic pump.

Unfortunately, the seals in the hydraulic cylinders deteriorate with time, and the service life of the original seals can be less than ten years in warm climates. This decay is a chemical reaction that gets accelerated by high temperatures or by additives to the hydraulic fluid. Each cylinder has four static seals that seal the front and rear caps and the hydraulic line ports, plus a rod seal that seals the moving metal rod to the cylinder body, plus a piston seal that prevents internal leaks and transfers the hydraulic pressure from the pump into movement of the cylinder's piston.

Typically, you will see your hydraulic cylinders leaking first at the bottom, where you wouldn't expect it. The first thought will be that an o-ring on the hydraulic line must be defective. It is actually the first sign that all seals need to be replaced. Seal replacement is absolutely not a DIY job, because the cylinders are crimped together. It requires special machinery to disassemble and reassemble these cylinders, plus all four internal seals have special shapes and sizes. The internal seals are not available to the public. Only the port seals (sealing the hydraulic lines to the cylinder body) are standard o-rings, but they do not normally fail unless they get damaged upon hydraulic line installation.

Top Hydraulics manufactures its own internal seals for your Mitsubishi hydraulic cylinders. They are a clear improvement over the original seals both in material and geometry. For example, the tiny flat rod seals get replaced with much larger cup seals, which will stay elastic much longer and are more forgiving towards scratches or impurities on the polished cylinder rods.

In the rare cases that a cylinder shaft got rusty or damaged by a tool (typically from someone trying to keep the tonneau cover open by putting pliers on the cylinder's shaft), Top Hydraulics can replace the shaft with a hardened stainless steel version from its own production (for a $100 surcharge). If there is damage to the cylinder housing from DIY repair attempts, then it will likely be rendered unusable and we will decline repairing it (in case you chose the rebuild option where you send us your part first), or you will lose your core deposit (in case you chose the core exchange option).

Replacing the travel sensor that clips onto the cylinder is NOT part of the rebuild service. If you need a replacement sensor, then please contact Top Hydraulics for availability.