Eple

Hello,
I am the owner of a 2017 MB GLC 350e. The other day I noticed the liner on the floor in the trunk (left side,just under the service hatch for the left side rear lights) was soaking wet. I got assistance from the local workshop (non-MB) to remove the water inside the car and get the liner fabric or insulation dried up. Afterwards we checked the drains from the roof panorama window and hosed the car without finding any more water inside the car. I then ran the car through a carwash and still no water inside the car. As the forecast mentioned upcoming rain, I left the car outside as a final "test"... and voila! I got water inside the car once again at the same location. All other parts of the liner fabric was bone dry, but the insulation under the liner had also become wet. My impression was the leak had to be somewhere under the service hatch in the rear left corner of the trunk. Perhaps for the water may be the gasket for the rear left light unit (no water is inside the light unit, though) or the overpressure rubber flap ? However, before the local shop starts dismantling I was hoping someone has had the same unfortunate experience, have identified the source of the leak and got it rectified. Any feedback on how to resolve this would be highly appreciated! Thank you!

ninobrn99

I had a 2008 B-Class that had a similar issues. There were some air vents behind the bumper that would clog up and cause water to ingress. There were some foam bits that MB ended up replacing.

Since then, I’ve been traumatized and check my GLC every now and again to make sure it isn’t happening to it.

Nino

talkr21

I had the same issue it was on the right in my moms 2017 glc300 water leaked into the trailer computer and threw up a bunch of errors. Dealer said $3500 to fix I went through my auto insurance to fix it

Eple

Prior to contacting the local MB workshop, I spent a fair amount of time myself in order to try to identify the location of the leak. So - here's an update and final closure of the thread;
1) It wasn't the air vents behind the bumper.
2) It wasn't the seal behind the left rear brake/turnlight unit. I did however get the foam/rubber seal replaced in order to rule it out.
3) It wasn't the trunk doorseal.
4) It wasn't any of gaskets on the plastic clips fixing the plastic cover on top of the trunk opening.

I did identify that water appeared inside after pouring water in the rear part of the left roof rail. Afterwards I made an appointment with my local MB workshop.

The MB workshop confirmed water to enter the car from the area identified and moved on to remove internal covers.

----> It turned out my car was missing a rubber gasket (!) for the rear bolt connection of the roof rail AS WELL AS having a leaky weldseam (!).

Once it had been repaired, I received an invoice of 1200 Euros. Must say I am disappointed in Mercedes-Benz with regards to the brand quality. Apparently, the matter was not a quality issue which (in my view) Mercedes-Benz should rectified free-of-charge. In my view, however, it's of course a Mercedes-Benz quality issue. As an owner I do expect welds to be watertight and intended gaskets to be mounted by the factory.
Nevertheless, I ended up paying and was about to leave the workshop when my parking sensors appeared to not be working (note: they did work when the car was delivered to the local workshop!). It turned out the workshop hadn't re-connected the rear sensors as these apparently has a connection box in the rear trunk ceiling (?) which were disconnected in order to gain internal acces to the roof rail bolts.




To sum up my experience; This whole ordeal has been a series of disappointments with regards to the Mercedes-Benz brand quality and its workmanship. Must say it has made me re-think my car ownership even though the issue has been resolved (at my expense!).