I'm sure alot of people here know, but for those who don't, there is a common passenger side A-pillar leak in these trucks. Mostly difficult to find. I have this problem.
I did all the fixes on this site and still had the leak. I took off the cowl and cleaned the drains. I covered the air inlet by the blower. No change.
I then removed the passenger's exterior A-pillar trim and weatherstripping and found this:
Those pictures are from another thread but I had the same exact weatherstripping adhesive failure. I removed all of that old sticky goo from the A-pillar and from the weatherstripping itself and resealed with two full tubes of black Permatex RTV. I made sure to leave the two drains in the weatherstrip open.
I STILL HAD THE LEAK.
I then took Ripshift's advice and sealed here:
If you seal here, pay attention...the outer 1/4" of the weatherstrip is a drain and it is open on the top. You don't want to seal this.
It rained a couple days later. Passenger floor was soaked!
Perplexed, I noticed there was a small bead of water between the passenger's interior A-pillar cover and the body color dash molding. I removed that piece today and had my girlfriend soak the truck. For about an hour I saw no leaks anywhere. I soaked the cowl...absolutely nothing dripping anywhere.
Then, I saw it. It took quite a while to appear, and I only saw it when I was putting the interior A-pillar cover back on. In the top right corner of the passenger's A-pillar, right where I STOPPED sealing with RTV originally on the corner (by the torx bit)...little drips of water were coming in. Here is where it leaks:
I removed the weatherstripping across the top above the windshield. The entire adhesive along the weatherstripping has completely failed as in the pics above. it's just a clumpy gooey mess. Water leaks under the weatherstripping where the adhesive has failed and pools in low spots such as the A-pillar corners...and drips into the truck behind the kickpanel.
I'm in the process now of resealing the entire top weatherstripping. I've cleaned it with Goo-Gone and 91% alcohol. In a little while I will reseal it with the black Permatex RTV. I will put an extra amount toward the A-pillar corner by shoving the tip of the caulking gun deep under the weatherstripping.
If you have a persistent A-pillar leak, it just might not be leaking at the A-pillar itself or cowl. Check the top weatherstripping all the way across...over time water drips down past the failed adhesive, seeps to the corners, and leaks inside the A-pillar because the truck isn't flat on the top.
I will follow up on this thread if my leak is finally gone. Hell, I'll follow up if it's still there too.
Now...back to work with the caulking gun!!!!!!
BTW...whoever decided to use such a POS adhesive can suck a giant caulk-ing gun!!!!!!
Hope this helps!