Had a weird leak that I just took care of, and figured I'd post this up in case someone else has the same issue and is pulling their hair out.
Quick Summary: The rear sunroof drain hooks onto a barbed plastic fitting at the rear of the cab so it can drain out the back. The fitting had a neoprene gasket that was folded over itself, installed wrong at the factory. Parking the truck either level or with the Driver's side rear as the lowest point meant that water draining from the sunroof channel would come right back into the cab.
I let my truck sit with a few inches of snow on it recently while at work; all the snow melted in one day. Came out after work and the inside was totally covered in condensation - windows, trim, everything. I figured I'd had a Nalgene leak in the back on the floor.
Left the truck parked in a driveway that has a slope so the front was elevated a bit and didn't drive it for 3 days. Tons of rain. Ended up with about 1-2 liters of water in the back floorboards and a bunch of mildewed cargo. I thought maybe it was just water leftover from the snow, so I dried it all out.
Got more water when it rained again. I found it was running from the driver's side lower rear corner of the cab and down to the sill trim.
Things that could have caused this that it turns out were not happening:
- Sunroof drain tube worn through or disconnected
- Crack in the cab seam, either above or below the rear window
- Leaking rear window, particularly on the sides where it bolts in
- Bad seal around the cab air vent
Other known causes for leaks elsewhere:
- Missing neoprene seal washers around front seat rear positioning posts (water under rear of front seats)
- Clogged sunroof drain tubes (water around sunglass holder or coming in around the bottom of the A or B pillar)
- A/C vent shenannigans
- Leak around the roof rack bolts
I figured it was the window or cab vent, since I had no water in the headliner. Let the dealership leak test it. They told me it was the driver's side rear sunroof drain tube clogged, and put a part on order.
Now, it sort of rains a lot in the PNW and I was concerned about how to keep this thing unclogged in the future. I assumed it got clogged with silt, because we drive a lot of miles on dusty roads. The front drain tubes are easy to clear with some plastic string trimmer line, but there seems to be no way to get to the rear drains from the top without dropping the headliner.
Solution:
- Fold the seat backs forward.
- Remove door sill trim piece (pops right out)
- Unbolt lower seatbelt anchor. 14mm bolt. Move it up high out of the way.
- Pull door seal molding away from the rear of the door frame
- Pop off the plastic trim piece below the rear window. Be careful of the top center plastic tab on the back. Move it out of the way so it rests on the seat backs (it still has the center belt webbing running through it).
- Pop off the rearmost side interior plastic trim panel, the one that runs from floor to ceiling. It will leave behind a bunch of orange clips that you'll need to pry out later and put back on before you replace it.
- Now you can pull off the thin felt-like interior trim that covers the back wall of the cab. You don't have to take the whole thing out; the drain tube and drain grommet (part number 748168J010 EDIT - this PN is wrong, the Nissan parts diagrams have the wrong part number on them.... ) will be under the bottom outer corner.
I got all this yanked apart with the idea that I'd clear the tube from the bottom to stop any leaks until getting a new tube. What I found was that the tube was perfectly fine - there was a neoprene washer around the grommet that was folded on itself on the bottom side, so as water ran out of it, surface tension would let it buttonhook around the bottom and right into the cab. The crud marks told the whole story. As it turned out, this was defective the entire time I've owned the truck (2015 model, bought new), and simply didn't leak enough to notice because my previous driveway was sloped in the opposite direction.
Popping the grommet out will greatly weaken the plastic tabs; if you have to take it out, I'd suggest ordering another one to replace it. I put mine back in for now with the washer arranged correctly, and pouring water down the sunroof channel shows that it's draining properly without leaking.
I also took some tin snips and cut around the felt trim piece so that I don't have to remove it in the future to access the grommet/drain; all I have to do is unbolt the seatbelt anchor and pop off the 2 plastic trim pieces.
Edited to add: Another night of pouring rain, no leaks.
Quick Summary: The rear sunroof drain hooks onto a barbed plastic fitting at the rear of the cab so it can drain out the back. The fitting had a neoprene gasket that was folded over itself, installed wrong at the factory. Parking the truck either level or with the Driver's side rear as the lowest point meant that water draining from the sunroof channel would come right back into the cab.
I let my truck sit with a few inches of snow on it recently while at work; all the snow melted in one day. Came out after work and the inside was totally covered in condensation - windows, trim, everything. I figured I'd had a Nalgene leak in the back on the floor.
Left the truck parked in a driveway that has a slope so the front was elevated a bit and didn't drive it for 3 days. Tons of rain. Ended up with about 1-2 liters of water in the back floorboards and a bunch of mildewed cargo. I thought maybe it was just water leftover from the snow, so I dried it all out.
Got more water when it rained again. I found it was running from the driver's side lower rear corner of the cab and down to the sill trim.
Things that could have caused this that it turns out were not happening:
- Sunroof drain tube worn through or disconnected
- Crack in the cab seam, either above or below the rear window
- Leaking rear window, particularly on the sides where it bolts in
- Bad seal around the cab air vent
Other known causes for leaks elsewhere:
- Missing neoprene seal washers around front seat rear positioning posts (water under rear of front seats)
- Clogged sunroof drain tubes (water around sunglass holder or coming in around the bottom of the A or B pillar)
- A/C vent shenannigans
- Leak around the roof rack bolts
I figured it was the window or cab vent, since I had no water in the headliner. Let the dealership leak test it. They told me it was the driver's side rear sunroof drain tube clogged, and put a part on order.
Now, it sort of rains a lot in the PNW and I was concerned about how to keep this thing unclogged in the future. I assumed it got clogged with silt, because we drive a lot of miles on dusty roads. The front drain tubes are easy to clear with some plastic string trimmer line, but there seems to be no way to get to the rear drains from the top without dropping the headliner.
Solution:
- Fold the seat backs forward.
- Remove door sill trim piece (pops right out)
- Unbolt lower seatbelt anchor. 14mm bolt. Move it up high out of the way.
- Pull door seal molding away from the rear of the door frame
- Pop off the plastic trim piece below the rear window. Be careful of the top center plastic tab on the back. Move it out of the way so it rests on the seat backs (it still has the center belt webbing running through it).
- Pop off the rearmost side interior plastic trim panel, the one that runs from floor to ceiling. It will leave behind a bunch of orange clips that you'll need to pry out later and put back on before you replace it.
- Now you can pull off the thin felt-like interior trim that covers the back wall of the cab. You don't have to take the whole thing out; the drain tube and drain grommet (part number 748168J010 EDIT - this PN is wrong, the Nissan parts diagrams have the wrong part number on them.... ) will be under the bottom outer corner.
I got all this yanked apart with the idea that I'd clear the tube from the bottom to stop any leaks until getting a new tube. What I found was that the tube was perfectly fine - there was a neoprene washer around the grommet that was folded on itself on the bottom side, so as water ran out of it, surface tension would let it buttonhook around the bottom and right into the cab. The crud marks told the whole story. As it turned out, this was defective the entire time I've owned the truck (2015 model, bought new), and simply didn't leak enough to notice because my previous driveway was sloped in the opposite direction.
Popping the grommet out will greatly weaken the plastic tabs; if you have to take it out, I'd suggest ordering another one to replace it. I put mine back in for now with the washer arranged correctly, and pouring water down the sunroof channel shows that it's draining properly without leaking.
I also took some tin snips and cut around the felt trim piece so that I don't have to remove it in the future to access the grommet/drain; all I have to do is unbolt the seatbelt anchor and pop off the 2 plastic trim pieces.
Edited to add: Another night of pouring rain, no leaks.
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