Awful Smell After Raining

2015 Toyota Tundra CrewMax w/ Sunroof

I have an issue that ONLY occurs after it rains. Absolutely no other time at all. The cab of the truck smells awful after it has been raining and I have been trying to troubleshoot where this awful smell is coming. I am at a loss at this point and looking for other ideas on where to try and find the issue. Smell is gone after a few minutes from airing out the car and driving. Issue popped up out of nowhere a couple of months ago and I have not done anything the would have caused it. Here are the details and what I've done:

• I have removed the back seats and inspected the rear glass seals. No moisture/dampness around the rear window or floor. Inspected seals around all four door windows and windshield. No moisture/leaking found.
  
  
• I have removed the headliner and inspected the four drain tubes. Grabbed a funnel and ensure water flows through each one and comes out under the car through the pinch welds. Ran bleach down all for tubes and used a thick weed whacker line to ensure nothing was building up in the tubes. Also, headliner has no signs of moisture stains.
  
  
• Inspected around third brake light. No signs of stains on the headliner or moisture found around the seals.
  
  
• Inspected under the front seats and footwells for any moisture. None found. Carpet is dry.
  
  
• Immediately ran AC on high. Smell is not coming from AC vents. I also swap between recirculation and fresh air from time to time. Plus, smell would be consistent if it came from the AC and not just after it rains. Also used a can of Ozium Air Refresh to no avail.
  
  
• I have tried to immediately smell around the cab each time after it rains to find out where it is the strongest and just my luck, no area is stronger than another.

What am I missing to try?

 

Does it smell like death, piss or like chemicals? You probably did this and since it's not coming from the vents it's a long shot, but cabin air filter and maybe inspect the hvac ducting that comes up under the driver and passenger seats to see if something crawled in. It sounds like humid air is flowing over something nasty.

 

My first thought too...

@FRSMichael Can you confirm you changed the cabin air filter?

 

Open your sun roof and send weed wacker wire down all 4 drain holes

 

It has a mildew type smell. I looked down the vents on what I could see with a flashlight (can't see much) but they were empty. If something was in the vents, the smell would be present the entire time and not just after it rains I would think.

Cabin filter was replaced after the smell started. Smell is still present. I forgot to mention that.

 

I've already done this and made the statement in my original post.

 

Another note is that I even covered the sunroof with a trash bag sealed with painters tape over this past weekend. It rained both days. Smell still present after raining. Removed and around the sunroof was dry.

 

Check where the leaves and crap collect between the front door and fender.

 

Lift the carpet and see if it’s wet underneath

 

There is nothing around the hinge area between the fender and the door. I lifted up the hood and there are no leaves or other debris near the hood hinge that leads to the inner fender well. I will need to pull back the fender liner to see if anything is behind there.

Already checked under the carpet in the footwells and rear seat area. Only spot that I didn't check due to clearance/lack of access is under the front seats.

 

Just parked in the rain does it too or only if you drive in the rain? (Water moving by gravity versus forced at speed)

Couple ideas.
1. Open front door and pull out rubber flap down low that leads into fender. I found a few inches deep of debris in there on mine.
2. Have you pulled door panels to look inside?
3. On a dry day with no smell, run a lawn sprinkler under cab for a while. Maybe up to an hour. Then check for smell. This will tell you if there is a leak down low possibly wicking up into floor pad or something.
4. Have you been offroad any? Check all around frame rails, top of skid plates, crossmembers, on spare tire, etc for anywhere clumps of dirt might be lodged. I've had some nasty smelling mud get up under truck that you only smell when wet. Made driveway smell like a musty swamp after hosing underside of truck and took a few washes to clear it all out.

 

https://www.tundras.com/threads/spi...ems-for-some-toyota-owners.18389/#post-412857

Long shot but something to look at.

 

From my experience so far, this only occurs when it rains and the car is parked. Now, it could happen while driving in the rain but the smell is never present. Could be a result from having continuous air flow while driving but never a smell while driving.

1. I'm going to check that this evening.
2. I have not. I did not see signs of moisture at the bottom of the door where the panels end so I haven't checked it. I'll check that this weekend.
3. I haven't thought about running water from under the truck. This wouldn't explain the smell when it rains (coming down obviously).
4. I have not gone off-roading in the truck. I've been under the truck countless times (even checked the drain port right above the transmission). No buildup anywhere.

 

I have had a similar issue and done similar things. My only thing I can think of is mud or organic materials found their way into the door or rear window area and when it gets wet it smells a bit. I guess I’ll have to open them all up and hose them out. Frankly I’m a bit lazy and it’s hot so may wait until it cools off.

 

Maybe you have water getting in from your 3rd brakelight?

Have you changed that ever and broken the oem seal?

 

Already checked that (see bullet point in OP). It has never been changed or removed.

 

Ok so I would get painters tape and plastic sheet. Cover the left side of roof and door sills. Smell? If yes, cover right, smell? Cover just windshield area, smell?

Might help narrow things down. Try to cut your problem into a smaller area to analyze.

 

Good idea to try. Just need to plan on when I don't need to use the truck and time that with whenever it looks like it is going to rain. That's the tough part.

 

Underneath the rubber cover at the very bottom. Unlikely this is the culprit but might wanna check just in case.

https://www.tundras.com/threads/leaf-litter.10087/#post-166776

 

Do the partial cover up suggested and use a garden hose to simulate rain.

 

This is a weird one. Mildew smell is what threw me. After seeing all the places you'd checked I was sure it would be a small, old animal carcass wedged somewhere, possibly between cabin and bed that would get wet and be pungent while it was wet. But the mildew smell and not from the vents adds to the mystery. Next thought was cabin filter (that you've replaced already) as I've had mine get wet from underbody "special" in car washes and then the whole box smells once the mildew takes hold, even if filter is replaced; BUT this was in a 2019 F-150 AND could def smell through the vents the strongest. Now I've realized that I was just typing as I was thinking and have written a very long version of, "I got nothing."

 

Get a moisture probe off Amazon. Probe carefully headliner near sunroof, carpet in corners, etc. You have a leak.

 

You've probably got a clogged drain in one of your doors. I had this happen in my other car. The stuff that makes it in the seal between the window and door collect in there and can trap water, especially after it rains.

 

This one gets my vote.

 

I had a foul smell once but it was because I forgot to shop vac the Taco Bell farts out of the seat cushions.

 

AC evaporator coil in the cab? May need to do the super cleanse with the Amazonian sourced cleaning spray. The AC weep hole is the easiest place to apply it. Below video is one of many describing some effective cleaning methods. When it rains, the fresh air intake likely gets some moisture exposure that dials up the already getting musty coil from 7 years of use.

https://youtu.be/_QWbFimZ_Gs

 

This is what I was thinking as well. Especially if your in a humid climate.

 

Already checked this. Driver side had some debris but not much. Cleaned out. Passenger side was empty. Issue is still present.

I will look into this!

 

Did you ever get to the bottom of this?

 

@OP,

I recently had this same problem and it’s been driving me crazy. Randomly I noticed overwhelming smells of cat pee/wet soccer cleats when I get in my truck after being closed for awhile. At first I thought it was wet carpet but I ruled that out quickly, along with cabin filter and AC. No odor from the ground up but then I remembered that the smell seemed strongest when I opened the moonroof cover. So I just went out and did that and checked the seals and found the smell. It’s the fabric bug visor that flips up when the moonroof opens! I ran my nose across the edge of the moonroof and traced it back to exactly that. It’s visibly damp. I’m going to air it out and hit it with Lysol then air dry again but that’s the culprit for me. Wanted to share as this has been driving me crazy.