Reading Skolman's post made me think of something...guys with the newer trucks that already came with the black deflectors may be tempted to remove them for aesthetic reasons, or may possibly break one when putting the door panel down after removal. To those folks:

Do Not Remove and Discard the black plastic deflectors on the bottom of your door panel! They serve a purpose and you may end up with a lake (yes, LAKE, not just LEAK) in the cab of your truck if you delete them!

It's hit or miss, you may be fine if you chuck them, as my driver's side never seemed to leak, but why take a chance?

BTW, it's raining today, so I'm already going to get a chance to see if the fix worked, and if this was my only leak...fingers crossed

 

Well it's been raining all night and all day, and it's supposed to rain all night again, and there doesn't appear to be any new water there. It's tough to tell, as there was some residual water from the old leak that has been collecting in that spot, but with the rain that we've had, there would be a puddle there that's a few inches deep, the way it was before. So I think that I'm good Now I have to dry out the carpet padding and clean up the rust so I can put the carpet back in place and put the panels back on

 

Thanks for posting this, my '00 GMC door makes that creak/pop, I'm getting one of these!!

I was also having a problem with the L/S door check making a horrible creak/squeak when opening and closing the door...wouldn't you know it, there's a TSB in reference to this too, which also only applies to 99's (gotta love first year new models). New L/F door check PN: 15173407

 

Cool deal Curt, glad that this helped!

On a negative note, we had massive rain storms last night, big time rain, with flooding and the whole nine yards, and I got some water intrusion this morning Definitely not as bad as before, especially considering how hard it rained, but there's still a leak somewhere. It appears to still be in the door area, unless it came in from the rear window and ran down, as I park on a decline (nose of truck facing downward), as the water is collecting in the same spot. I checked around the rear window seal as best as possible with a flash light and the panels on, and I don't see any signs of moisture, but I may have to do some disassembly to really tell. I don't think that it's coming from the windshield/cowl area because when I check the padding in the front of the footwell, and put my hand under it and check the floor, it's dry there. Good thing, because whatever it is should be an easy fix, just may be hard to diagnose as sometimes spraying with a hose isn't the same as actual rain, as I've found out when water testing cars at work.

So I'm happy and bummed at the same time, I did fix one problem, but I still have another...

 

kinda figured that wouldnt solve all your problems with this fix since you said it would leak even when sitting for awhile..
I would check out the top cab seem maybe? i dunno..

 

Well, now I'm starting to wonder...we did have torrential rains, and areas are still flooded, and just for poops and giggles I checked under my driver's mat and it was wet, which has never happened before as far as I know. The leak on the passenger side is almost definitely from the door, as that is where the trail lies, I almost wonder if the water rose in the doors quicker than the drains would work. I mean, water shouldn't get in at all, but we did have some extreme weather...I'm going to have to water test it when I get the chance and see what's up.

 

Another update, we had normal rain all night and half of the day, and it stayed dry

 

OK, it's been a month since I last updated this thread, and we've had A LOT of rain lately and both the left and right floor pans are bone dry It was raining HARD this past Saturday, and allowed for flooding and the works. Now I'm starting to think that the water I originally found, after installing the deflectors, was just drainage off of the factory floor padding which was soaked. I had it pulled and wedged up for inspection and diagnostic purposes, and maybe gravity did it's job and all of the water that it was holding decided to take a trip

 

Alright billy my truck is leaking, fix it..
You should know where all the common leaks are after this thread, my carpet is getting wet right underneath the driver side rear pillar.. Body sealer...?? 3rd brake light??

 

OK brother, here's what I did and what I found...

I removed the headliner and all the panels necessary to get the headliner out...it's acutally very easy and straightforward. Sill plates, B-pillar panels, rear wall panel, etc.

On my truck, f*cking everything on the back wall was leaking, seriously. The seal for my rear window was leaking, but my rear window is/was a factory slider, that was replaced 3 times under warranty due to the plastic window frame cracking in the upper corners, allowing water to literally pour in. Finally the dealer installed an aftermarket CRLawrence rear slider, and the frame cracking woes were over, just sealing woes due to a shitty install job. If you have the solid factory rear window, you may not have this problem, I'm not sure if it's a common issue.

Yes, my 3rd brake light seal was leaking, and the gasket is not available on it's own, it's only available as the whole lens, which was like $70ish IIRC. Sooo....I sealed mine with Toyota FIPG, which is similar to RTV. It will definitely suck if and when I have to remove it to change a bulb, but maybe when that time comes I'll have the dough for a nice new shiney lens assy. You mentioned body sealer, and yes, I had issues there also. If you open either door, and go to the top of the rear of the door, right under the weatherstrip, and between the weatherstrip and the little black drip rail cover on the roof, you may find some factory bondo/sealer that is cracked straight through. Inside the cab, along the seams on the roof, I could see rust trails where water was getting in through those seams on both sides. I used the same Toyota FIPG (Form In Place Gasket) to seal those as it is black like my truck and the repair is virtually invisible, but Kent makes a really good clear seam sealer that I like and use at work. It comes out not as thick as RTV, but thick enough to spread nicely, then it sort of settles and spreads and works it's way into the cracks and crevices and seals perfectly.

After those repairs, all of my upper leaks were fixed. I even sealed the body vent gaskets with the Toyota stuff...which bit me in the ***, HARD. I enlisted the help of Rosie to spray the Reaper with the hose, which she was more than happy to do (of course she took the opportunity to "accidentally" soak daddy...a few timies ). Well, water was pouring in through the body vents...I was like WTF? Then, by looking closely I was able to see that the gray, foam, "gasket" had become porous like a sponge, and water was coming straight through it. All that my sealing job did was make it harder to remove the vents, and then it took me hours to clean off all of the FIPG by squeezing my hand in between the cab and bed, and working my fingers from the inside out Wanna know the worst part? The new damn REDISIGNED body vents were only $7.50 each with my dealer/friends with the parts manager discount. I gave myself all that damn work for like 15 bucks. The new vents are like a one piece deal, with a rubberish sort of flap around them that is the same black color of the vent. On the old vent, you can see the grey foam sponge in between the vent and body, so if you have the first style that I mentioned, the body vents aren't your problem and I'd be looking at the 3rd brake light assy and roof seams first. In your case, I probably wouldn't bother to pull apart the interior like I did, but go straight to those two items and seal them up first, let em dry, and water test, to save yourself some work if you're strapped for time.

Funny thing, my current third brake light lens gasket looked to be the same exact style gasket as the leaky body vent gaskets...I think that I coated it with the FIPG pretty good though. Well, obviously I did something right, as my truck is finally "water tight" (unless I drive it into a lake )

...and, I'll admit it, you were right, my issues were more than those silly door protectors, makes me feel silly about this write up.

If you want, I'll PM you my cell phone# so you can give me a shout if you run in to any issues or have any questions