Back wall's air vents are leaking water into interior. And yours are, too.

4Runners have vents too, just like every single non convertible does. I owned 4Runners up until laat year. Many reported leaks in their vents. If you don't have vents you can't hardly shut the doors.

 

Some cars have it where the front windows drop down like a 1/4” and automatically reclose/seal when your door closes. That’s how my other cars are

 

As of a week ago I noticed every morning (I am in HUMID and hot East Texas), that I have a metric fuck-ton of moisture on all of my windows and windshield, leaving the seats and floors damp as well, even my thick textbooks are waterlogged, cue the mildew smell etc. I take it to the dealership when I get off work one day, they have it for two days, I have to call back to get a reply. The service guy tells me it is definitely the third brake light causing the leak, I am suspect of this because I took the back wall off and saw no indication of water coming from the top.. he ordered one, however they are on backorder and he has no timeline of when they can get my truck fixed. So I asked him what the hell I'm supposed to do about the moisture and mold risk in my truck, and he says, "well I don't know if its supposed to rain this weekend or not" I told him it doesn't have to rain for this to happen, humidity is 90%+ every night here. And he said he can get back to me on Monday with a response to that when his service manager is in... In the meantime he can "hook me up" with a rental car. So, any ideas on what I'm supposed to do? I am super worried my cab is going to have mold in it by the time this is fixed. I have damp-rid tubs in there already, and they only help a little bit. Maybe I should take it to Toyota's larger dealership an hour away in a larger city? Not sure what that would accomplish, but they have better reviews..”

My post from another thread, I too suspect my moisture is coming in from those vents, the liner on the back was only wet on the bottom just as yours was OP. We will see when I get my truck back I guess, at least they put me in a 18’ OR for the time being.

Edit: Had a torrential downpour for over an hour last night, this is going to be awful.

 

Well for now no moisture or water. I am watching it hard. Third brake light and now the vents. I think I will silicone those vents (the area around them where they contact the metal).

 

Seems the 2020 still has the same issue. Found some water in the bottom of the cab as I was in the midst of my audio upgrade. I used silicone around the vents and am now hitting it up with gorilla flex rubber paint. I can't afford water coming in as the Subwoofer box is MDF wood.

 

Same issue on my 2016. During a bad rain the carpet and padding to soaked. Replaced under insurance and I rtv’d the vents in place.

 

You would think they would have sorted this out over the years.. Apparently not.

 

Seem to have the same issue..

 

I can also confirm that sealing the outside of the vent box does absolutely nothing .. water continues to enter through the flaps. I used silicone and sprayed gorilla rubber paint and it made no difference

 

I’m going to try using gorilla sealant on mine. I also had my tail light leaking so I had to pull that out and seal it up as well.

 

Good luck.. I had my exchanged as a pay service . In order to keep the warranty. Over a grand in labor to “check floor mats” in order to exchange the vents out you have to pull the bed off.

 

No warranty here! nearly 200,000km

 

Could also be the HVAC. The owner's manual has a note on it which says:

"Ventilation and air conditioning odors
●To let fresh air in, set the air conditioning system to the outside air mode.
●During use, various odors from inside and outside the vehicle may enter into
and accumulate in the air conditioning system. This may then cause odor to
be emitted from the vents.
●To reduce potential odors from occurring:
It is recommended that the air conditioning system be set to outside air
mode prior to turning the vehicle off."

 

This post is from 2016 ….I hope they fixed it by now lol

 

They did not.. Mine is a 2020 TRD off road.

 

I just had a look behind the seats and didn’t find any evidence of water intrusion from the area of these vents after 3 years. Frankly if I had the problem I would suspect the outside seal and not the vent itself. However, @JimResnikoff says that’s not the case, it’s the vent itself. I wonder if the leaky vent could be installed upside down? The vents appear really sheltered on the outside so it looks difficult for water to enter. Also not that many reports that I’ve heard about and mine are dry.

Just my $0.05.

 

@wiljayhi Good for you on checking. It seems in my case at least the vents were not aligned correctly for the factory. I found this out using a bright light on the outside bed rail pointing down at night. From inside the cab you could clearly see a line of light at the top of the vents. Also water would run down the bulkhead and thus through water tension / adhesion would make it's way in the cab.

 

Are we absolutely sure the water intrusion is from these vents? There’s a recall TSB for the third brake light leaking. Toyota will replace it if you bring it in to the dealer.

 

If you like I can dig up the Video clip that I showed the dealer.. You can watch the water drip... so yea, in my case I was pretty certain it was coming from the vents and not the 3rd brake light since I watched it happen. Not saying this happens to every tacoma, but a quick google search will show you that this has been an ongoing issue for years.

 

I tried that gorilla sealant. Didn’t work worth a . I ended up using windshield urethane. Worked awesome! I also used it in the 3rd brake light. No more leaks.