Had some nonsensical, persistent leaking in rear cargo area near D-pillars. It's soaked the carpet, floor, caused some surface rust on components and a bad wiring ground on the D pillar. I redid both sunroofs, new windshield, new plenum/cowl, new A-Pillars, checked roof rails. Maybe this documentation helps someone, I've been determined to fix before the PNW rainy season and the clock's ticking. I fixed it.

First - a quick video of the damn leak Crappy Video Explaining My Leak

I resealed these areas to fix the rear leak:

1) Rain gutters from a-pillar all the way to the cargo door (did not fix, but I feel better now that I can't see cracks in sealant)
2) Per a TSB attached, the seam over the cargo door that you see once you remove the overhead rubber seal (helped, was leaking)
3) A weld on the roof over the rear cargo door under the plastic trim that runs across the top (solved the leak)

Where I went wrong. I assumed it was rain gutters which had cracked sealant. This:


Looks like crap

Really looks like crap back here. But apparently wasn't leaking!

However, after re-sealing the rain gutters, still leaking, no change. BTW to redo the rain gutters, I made a bit of a mess with $24 a tube 3M polyurethane seam sealer in a caulking gun. Fom A Pillar to rear. However, said mess is all covered up by the plastic rain gutter trim.The stuff was supremely sticky even with a finger and thinner I couldn't get it go be smooth. So much for my bodywork career. (I guess proper repair here is a body shop digs out the old cracking seam sealer and replaces with self-levelling). Big waste of a Saturday but I do have reassurance that the rain gutters won't leak now.

So I found this TSB (attached) that said.. water ingress in rear may be due to missing seam sealer from manufacture. My truck was in LA, CA (18 years) and TX (1 year) and ... I bet this was never addressed.



Leak location, looking up, pass side D pillar area



Hard to way find but this is upper rear passenger D pillar, looking up from below. You can see the drip of water. This is where water entered the car... but where is it entering the interior of of the panels?

I started using a turkey baster to squirt water in the exact seam mentioned in the TSB and THAT was it. It travelled inside the frame and came out where the welds all meet.


Right in that seam above where my finger is, water is getting in. This is the seam in the TSB (that then goes up and over the cargo door too)



Water tested. Damn. Still had a leak. But much less coming in. So -- Above the rear cargo door on the roof there are two panels joining. The seam sealer was cracked off / flaking off. Again, water getting in and then coming inside.


Also and I have no idea how, it was leaking here, between these 2 seams. This is not what's in the TSB, it's right above it. Under the plastic roof trim. But the strip of sealant was flaking off and water defy getting in here







Sealed it up.. just a small bit on the edge since the plastic trim has to go back on.

Left hose on for 60 minutes in all variations while I sat in car on my computer working, bone dry.



So -- check these 3 areas. I bet a # of trucks have dried up or broken down seam seals up here.

 

Cheers @nashvegas !