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Water leak from under dash on drivers side!

Brad 2004 4x4

New Member
Joined
Jan 23, 2021
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4
Hey everyone, this is my first post here on Chevy Avalanche Fan Club. Hopefully someone out there has had this problem.

I have had water leaking into the cab now for a few months, it is dripping off of the E brake pedal but it seems to be coming from above that and just making it's way onto the brake and dripping onto the carpet. I have a 2004 Avalanche 4x4. The windshield was replaced about a week ago, I was hoping that would take care of the leak as i thought it may have been running down the inside of the driver pillar and behind the dash. New windshield and still leaks in the same exact spot, and I told the shop about the leak before they replaced the windshield to make sure they sealed it nice and tight. I installed some weathertechfloor mats recently so It just drips onto that mat now where I can wipe it away. But it doesn't solve the problem, I have sealed the wire boot at the door with silicone, and also sealed the main wire harness that enters the firewall on the drivers side, but I still get a small puddle when it rains on the floor mat under the E brake pedal. This only happens when it sits in the rain, not while driving. Any help much appreciated yall!
 
First welcome to the website.
There are a mountain of older threads discussing leaks with various issues and solutions. You may want to spend some time reading them. You seem to be on the right track with your troubleshooting. Another area to check is if you have a sunroof, both sides have drains and drain tubes which run down the A pillars and you may want to check if the drains are disconnected or the tubes have a hole etc.
Good luck in your efforts.
 
Do you have a sunroof? I think Vaeagleav is steering you right. The drains clog easily, and can/will leak straight down that pillar depending on where the clog (or disconnected drain line) is.
 
No my avalanche does not have a sunroof. Thanks for the replies guys. I have spent some time and searched through some threads about water leak issues, that is actually why I decided to join this club because I saw how helpful everyone is to each other on here and i liked it!

I've heard about the factory body seams not being seamed perfectly and causing leaks. The shop pulled the cowl off and vacuumed the debris out so I know the water is not backing up. I believe it is coming through somewhere around or beneath the cowl area on the outside of the vehicle and making it's way in, but I could be wrong! I've been stumped for a few weeks now trying to pinpoint it as it doesn't seem to leak everytime I get it wet. For example I washed my truck today and did not get any water drip onto the floormay. But the other day it was parked in the rain overnight and there was a small puddle of water left on the floormat when I opened the foor. Mysterious!

Brad
 
Check firewall where they use rubber grommets to let wires and such inside cab... maybe one is torn or hasa hole or such.
Any mods that have wires going thru one would be the first I check.

Other thing is if you have onstar antenna on roof over drivers head... maybe it is leaking?

Worse case... you pull drivers seat and lay down under dash and close it up tight while someone uses hose and starts from bottom and works their way up until you find source...

Good luck
 
I've sealed the firewall grommet with clear silicone, and I do not have an on star antenna. I've tried to get my head under there to see where it's coming from with a hose on it but I just can not seem to pinpoint it, I suppose with the drivers seat out like you stated would help with being able to get under there a bit better.
 
Brake booster linkage & bolts as well as steering column penetrate firewall and have to be sealed.
Door rubber boot for wires etc.
RUST HOLE?

I would tear it apart and dig under that dash board..
MAybe remove cluster to see up high in dash?
 
I don't know if it's been covered here, but the leak I was having on the passenger side only was coming through a cover on the outside cowl.

This video shows exactly what to do to fix this exact situation. The truck in the video is not the same years as the Avalanches, but it is the exact same issue. Around the 2:50 is where the point of entry for the water is coming from.
I did this repair 4 years ago and haven't had a water leak since.





 
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