Water leaking on passenger and driver side floorboard when it rains

[dyeager535]

I had to unstick my wipers from the windshield the other day, so poured water on and just watched what happened on the passenger side as the water ran into the cowl. It immediately started pouring out the front, under the hood, running directly onto the heater box. I sealed that up so not where mine is leaking, but my understanding is that this water SHOULD have gone down behind the inner fender, not poured out the front like that.

Pretty obvious GM expected water to come out where I saw it, the rail stamped into the heater box was directly where the water poured out, but I suspect that isn't normal on flat ground without a huge volume of water, which I was not pouring.

 

[WJACKSON11X]

Just got back in town so I will be trying to figure out my water leak issue. I removed the dash pad, bezel, and cluster lastnight. While I was in there, I replaced all of the bulbs with LED bulbs ( a big improvement). Should be a lot easier to follow the path of the water with the dashpad removed.

 

[jeff in co]

I looked at mine last weekend and found that there is, in fact, some plugged channels from the cowl vent area. They are located on both sides of the truck and need to be cleaned out. I just put a vacuum in the area and then used a wire to loosen the debris all up for the vacuum. I think that is definitely contributing to the leaks inside.

The other area I noticed is the vent mechanism on the inside of the truck. When I ran the water, I noticed it was coming into the cab via some screw holes that I did not have screws in. Also, the vent mechanism actually has a seal all the way around it so I assume they expect some type of waterproofing seal was needed. So, for the screw holes, I just placed a dab of silicone in the holes and then made sure I bolted the whole thing down, leaving no unused screw holes.

So far, so good! Hopefully that was the major portion, and with any luck, the whole solution!