The water leak in the boot of the W211 has been resolved.

[Mistral]

I have successfully located the source of the water infiltration into the spare wheel well region of the car's trunk. I replaced the gaskets for both tail lights and the rubber seals on both sides. Unfortunately, I have not been successful yet. Subsequently, I tracked the path of the water flow and saw that it runs beside the boot rubber seals, as indicated by the side trim pieces. Furthermore, I noticed a disparity in the panel on the left, but the right side had a somewhat narrow gap. To rectify this, I used a dolly to gently hammer down the left side, aiming to achieve a somewhat similar alignment. I purchased a new rubber seal from authorised dealers, together with rust converter and sealer, which resolved the issue.

If you have water in the boot region, I suggest inspecting the rubber seal for any symptoms of rust, particularly in the lower section, before purchasing a new gasket or rubber side trims. It may just need a £5 sealant to repair the region, unless you are really meticulous. The closure of the boot has become somewhat more difficult after the replacement of the boot seal.

[Paqngo]

Impressive display of investigative skills, Amanda. Is there any reason for the significant gap in the panels, such as past damage from impact?

[Mistral]

Thank you! Regarding the gap, I am uncertain about the reason for the asymmetry between the left and right sides. I could not see any indications of prior damage, which leaves me perplexed as to the cause.

[Mistral]

Regrettably, the previous effort to rectify the water leakage in the trunk was unsuccessful.

After doing many further inquiry efforts, I used UV dye and discovered that water is infiltrating via the panel gaps shown below.

I should have noticed earlier, since there are now little areas of rust below.

I want to apply seam sealer to this area after doing rust treatment, sanding, and painting. However, it remains unclear as to the source of the entry point.

I followed the advice given in another post and generously applied silicone sealant to the rubber seal in the boot and the gaskets of the tail lights. In addition to some regions coated with silicone grease. The boot lid panel has been resealed with tiger seal. All of the rubber trimmings have also been replaced. The individuals mentioned in the typical suspects have been acknowledged and considered in accordance with the previous guidance provided by others.

Water does not immediately flow down to the marked sections when poured from the top. Creating a deceptive perception.

I am concerned that putting seam sealer to this portion may result in water flooding the opposite side of the panel, namely where the boot lock hinge is located. Since it is an electronic boot release.

Has anybody else encountered a similar situation previously? What precautions should be taken while applying seam sealer?

I purchased a brush specifically designed for applying seam sealant.

[Mistral]

It has been discovered that the source of water leakage is really the rubber seal around the boot. Discovered a component in close proximity and applied pressure to the rubber seal, resulting in the observation of water infiltrating the inside of the seal.

Although I replaced it three years ago, I am considering purchasing a new one and installing it without any silicone oil or sealer, following the dry/factory method.

Uncertain about the specific orientation required for placing the seal. Do you have any guidance or recommendations?

[Paqngo]

The source of the leak on my W211 facelift model was the plastic side strips and the rear lights.

[Paqngo]

[Motoman]

On my vehicle, there was a leakage originating from the area behind the number plate holder. There were perhaps 16 or more potential places of leakage located behind it. Perhaps the third brake light as well. 👍

[Motoman]

It is recommended to use puraflex 40, available at Toolstation, on the metalwork. Then, proceed to place the seal in position.

[Mistral]

Indeed, I too engaged in the activity you mentioned subsequent to perusing your discussion. I have also sealed the boot lid plate with tigerseal at a body shop when installing a facelift one.

However, in this occasion, I monitored the water ingress specifically originating from the seal of the boot lid. Upon exerting pressure, water was seen to be flowing out. Furthermore, there are now rust spots present all around. I will address this issue and see the outcome. However, I am grateful for the assistance and contributions from everyone. If the issue is not resolved, it may be necessary to reconsider the other areas.

[AMG33D]

When using silicone sealant, it is important to avoid using acid-based ones since they might lead to metal corrosion when exposed to water. In my experience, doing smoke testing within a boot is the most effective method for pinpointing the precise location of leaks. I constructed my own smoker using an inexpensive pond smoker, a pair of computer fans, and a plastic tub filled with water. The entire cost of my setup was around ten pounds. However, it is also possible to rent a smoker if desired. It has always been successful in detecting leaks in boots.

[Motoman]

Are you a fan of Blue Peter?

[Mistral]

Shortly after replacing the boot seal, water returned with great intensity. I brought it to a Body Shop that identified the leak. There are two areas of rust below, where the seam seal has also deteriorated. We conducted a test by having someone enter the trunk and then I forcefully sprayed water using a high-pressure water jet.

Merely applying a seal on the outside has been shown to be inadequate. The optimal choice is to put sealant on the inside and exert pressure with your finger to maximise the amount applied. Since the application of seam sealer from the back requires the removal of the rear bumper.

Please note that I am now overseeing the temporary repair, which involves utilising a window bonding solution on the inside of the boot/panel until I am able to replace it correctly.