Water Leaking from Cabin to Bed

Hey guys, new to the forum. Let me start of by saying I am relatively new to the Chevrolet world, I just bought this truck of mine in October (2004 Chevy Avy 4x4). I am a Toyota technician and am not really familiar with the common issues of these trucks.

Last night after a weekend of deer hunting I was hosing out the bed and I dropped the midgate down to hand clean the back of the midgate. I noticed some water pooling up on the trum behind the rear seats. Today I removed the plastic threshold and the metal cover held down with the T-30 screws and cleared all the leaves out of the drain that is in the front of the bed. I then went back to the car wash to finish my cleanup job. When I was done hosing out the bed, I dropped the midgate to find water pooling in this same area. Pic is linked here.



I know it doesn't look like much in the pic but before I wiped it up it was a lot more. Is the water supposed to drain here in these trucks? I noticed the 2 holes in the trim, are they drains? If so they must be clogged. Now I did still have that metal cover off the truck when I washed the bed out, I don't know if that helps seal off the cabin, but I don't see how it would. Is this supposed to be this way or is there a fix guys?

I am a hunter and I absolutely, positively, can NOT have any "liquids" seeping from the bed into the cabin. Im sure you guys can understand why, as that would get a little stinky and messy. I am sure I am not the only hunter in the world that owns an Avalanche. I am hoping you guys can help a brother out! I am a little upset with this as I still owe money on this thing and selling it for a silverado pickup is not really an option Whats the word guys? Thanks for the help in advance and I am looking forward to getting to know you guys. Thanks .

In the bed, after removing the plastic grate.There are drain holes that a coat hanger wire should be able to pop through.
You should not be getting any water inside the cab behind the seat.

check your gasket too ... in the center of the pic it doesn't look like it is seated right .....

So the water is not supposed to drain on to that plastic lip behind the rear seats in the cab? When you say the drain holes are you talking about the one in the top corner of the bed that is really narrow? I still have that cover removed and I water tested it with that cover removed, I suppose that doesnt offer any sealing does it?

As far as the midgate seal goes, it looks ok but it is obviously letting water past it. I took a bucket and dumped water on the back portion of the bed, the midgate, and seconds later when I got in the cab and dropped the midgate, there was a puddle of water in that trim piece under the midgate

IS there any way to get a weatherstrip for the midgate that doesn't come from the dealer? Or any way to restore the one thats in the truck to "like new". Maybe inserting something inside? Depending on what the seal is designed like. I havent taken it apart.

get the part # for the gasket from the dealer .... then check around the web for the best deal using that part # ....

I sometimes use GMpartsdirect.com ... after I get my part# ... it is an actual GM dealer out of NC ....

John

believe it or not ... I found it ...

http://www.gmpartsdirect.com/catalog/frameset.cfm

enter your info .... click on body harware ..... go to bottom of page .... click on list all 73 images ....

look for the diagram of the midgate ..... part listing # 17

part# .... 20837689 midgate lower gasket ..... 81 and some change ....

John

The two holes on inside are a last resort type of drain.

Check your midgate gasket, some have use round foam and insterted into bulb to make it seal better.
Under midgate drain (grate) should be some drains.

Check this link for soem generic info from Chevy Tech:
http://chevyavalanchefanclub.com/cafcna/index.php/topic,34739.0.html

Well guys thanks for the info so far, you have all been very helpful. I was acutally just about to ask about those 2 drains inside the cabin. I really hope it doesn't start to stink up my whole cab considering there was probably bloody water running through there when I hosed out the bed. I have checked all 5 drains in the bed and they are all clear and water flows freely from them. I got all the sand and debris out of the bed and all the drains today at the high pressure car wash.

I guess considering that the water flows right in when you dump a bottle of water along the back of the midgate, the only answer is the midgate seal. I will get one of them ordered up tonight. Is there a lot involved in replacing them or do they just slide in like any old weatherstrip does? I hope that solves the problem, Im gonna have to take the seats and carpet up in the back to clean all the muck on the floor. Looks like this was a problem long before I owned the vehicle.

I am glad I asked you guys. One of my coworkers here at toyota told me that when he used to work at GM he saw this all the time and it was how the truck was designed. He said that the water was supposed to come in the cab and go out those 2 drain holes. Glad I found out that is NOT the case. I could not understand how someone would design a truck, a truck where dirty things go in the bed, to drain INTO the cab. I really love this truck and do not want to get rid of it, but as a hunter I can not have what I put in the bed getting into the cabin for sanitary reasons. Is there any additional things I should check before I condemn the seal? I dont see what else it could be considering the water tests I did, but I figured I would ask.

Does the hinged metal cover and the plastic grate that goes over top of it help in sealing the cab at all? I had all that off when I was water testing it, I dont know if that diverts the water at all or not. But it was off the truck and still is off the truck

FYI There's a thread stickied on here showing how you can put insert a length of plastic tubing into that midgate seal to "beef it up".  Sometimes it gets compressed to the point where it doesn't seal as good.  

I saw that thread but he only showed putting it in the corners, I am just going to buy a new seal to be sure. Im really hoping that is the problem. I am already fired up that I am gonna have to shampoo the hell out of my carpet 

I popped the covers off the bed drains at the midgate because they would stick and water would pool where yours is. I cleaned them regularly , but they would still keep water in. They were also raised above the bed floor, which didn't help matters. Haven't had a water problem problem since.

Avalanchedriver,

When you say the drains at the midgate, are you talking about the one skinny drain all the way at the front of the bed thats just a little bit to the left of the center of the bed? Thats the only one I see in the front. Ill pop the plastic off it tomorrow and see if it helps.

EFS463 said:

Avalanchedriver,

When you say the drains at the midgate, are you talking about the one skinny drain all the way at the front of the bed thats just a little bit to the left of the center of the bed? Thats the only one I see in the front. Ill pop the plastic off it tomorrow and see if it helps.

Click to expand...

I just emailed a couple PDF documents that might help you with your issue.

Thank you Joe! I appreciate those chapters and I am going to look through them this evening when I get back home! There is a light rain here in Maryland and it is pooling up in the back again. I definitely think one of my problems is the midgate seal which I am going to order from a dealer at work tomorrow. I might be able to get a discount on the part because the dealer I work for has a chevy dealer under the same name, going to see if I can get it cheaper than $80 before I order the one on gmpartsdirect.

Yes that's it.  I couldn't remember if it was one or two but it was long and I remember it being closer to the driver side.  It's been about two years. I actually had to break it to get it out. Before removing it, water would pool inside the midgate and would go over onto the carpet rather then drain out those two small holes. Since then no more water inside.

avalanchedriver said:

Yes that's it.  I couldn't remember if it was one or two but it was long and I remember it being closer to the driver side.  It's been about two years. I actually had to break it to get it out. Before removing it, water would pool inside the midgate and would go over onto the carpet rather then drain out those two small holes. Since then no more water inside.

Click to expand...

Thanks for the info I will be sure to take that drain out before I put the metal cover back on. Hopefully the dealer has my part in stock. Thursday Im gonna take the seats out of the back and fold the carpet up and clean all the muck out from under there. Hoping the bloody/watery mess I hosed out of there didnt leak into the cabin and on to the carpet to bad cause that will not be fun. But so far no bad smells and it was 70 degrees today. So, fingers crossed on that one.

Does the hinged metal cover in the bed, you know the one that is fiberglass and folds down with the midgate. Does that do any part of sealing the bed and cab? Or is it just there to fold down when you open the midgate. Mine is all cracked up and I was not planning on getting a new one as its $250. But I do not know if it provides any sealing. If it does then I obviously have to have it. But the mounts are cracked and the hinge is rusted in the up position so I am ready to throw it in the trash. Does it do anything to seal or is it not part of the water management and keeping water out of the cab? Thanks guys

I do not believe it has anything to do with sealing other then when the midgate is down it keeps junk from falling in that gap.

I also played around with the positioning of the midgate. If you lower the back seats you'll see two hinge covers. Pop them off and each hinge has two bolts mounting it to the floor. You should be able to tell if it's been moved as there would be multiple marks on the metal from the bolts. Mine had been moved (not a huge amount of play) and I put it back to where the other marks were. I had a friend lightly hose the midgate from the bed and no water got in.  So between that and removing that drain cover, I've been water tight. Knock on wood.

avalanchedriver said:

I also played around with the positioning of the midgate. If you lower the back seats you'll see two hinge covers. Pop them off and each hinge has two bolts mounting it to the floor. You should be able to tell if it's been moved as there would be multiple marks on the metal from the bolts. Mine had been moved (not a huge amount of play) and I put it back to where the other marks were. I had a friend lightly hose the midgate from the bed and no water got in.  So between that and removing that drain cover, I've been water tight. Knock on wood.

Click to expand...

Yeah I noticed that. I had the whole truck apart tonight had all the seats out the midgate out of the truck and all the trim panels in the back off to clean it up real good. I replaced the midgate seal and it seems to be ok for now but I was so tired and was tired of working on cars for the day so I came home without giving it a through test. Have to wait till the next deer I get and hit the car wash. To cold to be outside playing with water unless it is absolutely necessary

Looking at the original pic though and comparing it to what I saw tonight I'd say its fixed. I noticed that water would end up in that trough when you drop the midgate after testing it. The seal will hold the water there, then when you drop the gate down it ends up on that trim where the drains are. I did notice that if I blew off the back of the midgate with an air gun before dropping it, I had no water inside, and I did not have the streaks down the bottom of the midgate where you could see the water was leaking in like the first pic.

I don't believe this has been mentioned yet, but as much as the parts & pieces are designed to resist water intrusion, it is not immune from a direct or hard force of water be it from a typical garden hose or a power/pressure washer.

So I have the new seal in. I noticed something funny. I don't have a pic yet I can try to get one tomorrow. On both corners of the midgate, the raised edge drops down. Where this edge changes, the seal on the midgate is folded in some. Is that normally how it is supposed to be? I don't see how I could have the weatherstrip in wrong...I have put 100s of weatherstrips in and this one is no different from any others. Its almost like the corners are folded under. has anyone else noticed this?

Need pic.
Most issues are in the corners hence why some have stuff foam round things inside bulb.