Please explain what "drain cups" are ??!!

[FJD]

Hi All,

Can one of you informed members explain something to me. My 3 has been at the dealer for a water leak for the last 4 days. I talked to the service manager and he told me the leak was coming from the "sunroof drain cups".
Can someone explain to me:
A) WTF are "drain cups" doing in my sunroof (I would've thought the sunroof is sealed from water intrusion and thus would not need any type of "drain" anything!!!)

B) How/why this would cause a water leak in my cargo area passenger window??


I was sure the leak would've been coming from my roof rails rather than my sunroof !!

Any help in explaining this would be much appreciated !

TIA

[f5fstop]

Never heard the expression "drain cups," but possibly part of a drain hose has that description in the parts catalog.
All sunroofs, except for the aftermarket flip up ones, have some sort of drain system. All GM sunroofs I have seen have four drain hoses. Two down the A-pillar, and two out the rear. In the Hummer, both the rear hoses run in the C-pillar, which is the pillar behind the rear door, just in front of the rear side windows. The rear hoses exit just in front of the rear tires.
The drain hoses are necessary since to seal a moving pane of glass is hard, and in most cases, water will not enter the trough for access to the hoses. However, the hoses are there, just in case. In addition, if you forget to lower the rear of the sunroof and it rains, most of the water will drain out (I know this from previous experience).
Usually, what happens is someone at the plant incorrectly routes a hose, and it is routed inside, versus outside. So, water will leak inside. This is a rare type of leak.
Not sure why it is taking so long, unless they had to order a hose. Sometimes during assembly they can be damaged.

[Boar-Ral]

Originally Posted by f5fstop

In the Hummer, both the rear hoses run in the C-pillar, which is the pillar behind the rear door, just in front of the rear side windows. The rear hoses exit just in front of the rear tires.

So that is what those are.* When I pulled out the rear cup holder and cubby, I saw a rubber hose running down in front of the wheel well.* I wasn't sure what it was.* Learn something new every day!

[Hummerboy77]

Mine was leaking through the On Star mic one time after a heavy rain fall.

[FJD]

Thanks for the info F5 !!
It makes perfect sense now of why I was getting the water leak in the cargo area passenger window. From your explanation, seems like maybe the hoses weren't run correctly. I'm almost happy they found this as the problem area since I was convinced it was from the recently replaced roof rails! Guess that's why I'm not a mechanic!

Thanks again