Strong Mildew Smell After Rain. Two Dealers Can't Find Source/Leak

[Porpoise Hork]

This started up about 2-3 months after I bought the truck. In warm/hot weather (10 months of the year in Houston) after just about every moderate to heavy rain shower. Open the truck up after and I'm greeted with a very strong mildew smell. I have checked every inch of carpet when this happens and nothing, completely dry. Turn the A/C on and nothing no smell from either fresh or on recirculate. Also there's no water spots on the headliner or any evidence of a leak. Opening the windows up and drive around for 5 or so minutes is usually all it takes to clear it out and all is good, but on some occasions the smell returns but not as strong later the same day. The A/C drain is not clogged as water freely drains off and no smell is ever detected from the system at any time. Also on days where the mildew smell is present after airing the truck out, when driving at freeway speeds I will occasionally get whiffs of the mildew smell when following behind a semi other larger vehicle, but most of the time it doesn't happen. The only thing I have seen is a very small amount of water will be on the door sills on all four doors outside the weatherstripping. I have tried drying this up and leaving it to see if there is a difference, and it doesn't change anything. I have also checked the vents and carpeting on the back wall and no sign of water or mold/mildew there either. Last time I had the carpet panel out for sound proofing I even misted the jute to see if it was coming from that. Nope..

Off to the dealer to get checked out. First dealer sent it out to a third party company had it for three days and they couldn't find anything. I took it to another dealer who has an in house leak specialist and he spent 2 days looking at it... Nothing no evidence of a leak. They even had two moderately heavy rain showers that should have led to something while the truck was in their possession and nothing.

Both my wife and kids have also smelled it so I know it's not just me.

The only other thing I think I can try doing is take the garden hose and pour water on one part of the truck at a time like say just the back window seal, give it a couple hours or so and check the truck for the smell, then wash rinse repeat until I find it.

Has anyone else had a similar issue? Or am I just lucky....



** Update 8/10/21 **

Source of leaks have been identified. Driver's door leaking past the inner door seal. Rear window glass warped and not sealing correctly.

The wire harness in the driver's door got mounted in the wrong position and is causing water that seeps past the the window felt to drip on it and splashes towards the weather seal leaking past the and into the truck. The rear window is also leaking and water is traveling down to the driver's rear floor board.

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[AzScorpion]

It's a long shot but have you checked the cabin air filter? I would think this would make is smell all the time if it were moldy but it's worth checking. I think doing the water test might be your best option next.

 

[JACKSMYDOG]

This started up about 2-3 months after I bought the truck. In warm/hot weather (10 months of the year in Houston) after just about every moderate to heavy rain shower. Open the truck up after and I'm greeted with a very strong mildew smell. I have checked every inch of carpet when this happens and nothing, completely dry. Turn the A/C on and nothing no smell from either fresh or on recirculate. Also there's no water spots on the headliner or any evidence of a leak. Opening the windows up and drive around for 5 or so minutes is usually all it takes to clear it out and all is good, but on some occasions the smell returns but not as strong later the same day. The A/C drain is not clogged as water freely drains off and no smell is ever detected from the system at any time. Also on days where the mildew smell is present after airing the truck out, when driving at freeway speeds I will occasionally get whiffs of the mildew smell when following behind a semi other larger vehicle, but most of the time it doesn't happen. The only thing I have seen is a very small amount of water will be on the door sills on all four doors outside the weatherstripping. I have tried drying this up and leaving it to see if there is a difference, and it doesn't change anything. I have also checked the vents and carpeting on the back wall and no sign of water or mold/mildew there either. Last time I had the carpet panel out for sound proofing I even misted the jute to see if it was coming from that. Nope..

Off to the dealer to get checked out. First dealer sent it out to a third party company had it for three days and they couldn't find anything. I took it to another dealer who has an in house leak specialist and he spent 2 days looking at it... Nothing no evidence of a leak. They even had two moderately heavy rain showers that should have led to something while the truck was in their possession and nothing.

Both my wife and kids have also smelled it so I know it's not just me.

The only other thing I think I can try doing is take the garden hose and pour water on one part of the truck at a time like say just the back window seal, give it a couple hours or so and check the truck for the smell, then wash rinse repeat until I find it.

Has anyone else had a similar issue? Or am I just lucky....

I worked at a GM dealership in the late 80s, and Grand-Ams had a leak problem. I spent many hours peeling interiors completely out and having someone run a hose around the exterior while I searched out leaks from the inside. My knees are aching just thinking about it, lol.

I'd definitely start on the rear window. The top trim piece, below the window, comes straight off, and a leak would be easily seen.

The rear floor/wall/tool storage bins have a few layers and water could be getting under things, which may not leave exposed wet carpet if coming down the back wall, and under the floor.

 

[AzScorpion]

I worked at a GM dealership in the late 80s, and Grand-Ams had a leak problem. I spent many hours peeling interiors completely out and having someone run a hose around the exterior while I searched out leaks from the inside. My knees are aching just thinking about it, lol.

I'd definitely start on the rear window. The top trim piece comes straight off, and a leak would be easily seen.

The rear floor/wall/tool storage bins have a few layers and water could be getting under things, which may not leave exposed wet carpet if coming down the back wall, and under the floor.

It seems weird that he states this "Opening the windows up and drive around for 5 or so minutes is usually all it takes to clear it out and all is good, but on some occasions the smell returns but not as strong later the same day". If there's mold growing the smell doesn't just go away, the smell always lingers. I might notice it more than others as I'm highly allergic to mold and it bothers my asthma so my chest gets tight right away.

 

[JACKSMYDOG]

If it is under the carpet, the smell will come and go as the carpet surface dampens or dries. After time, the smell will not fade even as the surface dries.

 

[AzScorpion]

If it is under the carpet, the smell will come and go as the carpet surface dampens or dries. After time, the smell will not fade even as the surface dries.

One of my contracts back east was a large fire & water restoration comp. I would get to the house after it's been all dried out and at times I could still smell the mold where sometimes the customer couldn't. It's very dangerous and needs to be addressed ASAP before it gets out of hand. Hopefully Bret can find it before it really sets in.

 

[JesseS]

Someone posted that their cabin air vent (behind rear seat) was installed backwards and allowed water to enter and dampen the carpet. He even posted photos, look between the bed and cab and if you see a small black 'shelf' that may be the issue. You can't see them from the inside without removing the sound deadening material.

 

[FoD]

It's a long shot but have you checked the cabin air filter? I would think this would make is smell all the time if it were moldy but it's worth checking. I think doing the water test might be your best option next.

It's a long shot, but what about a rag on the inlet side of cabin air or between side vents and their outlets to engine compartment?

Also, is it only after rain or does it occur in humid days too?

 

[DukeCanBuildit]

Here’s a thought Bret…

Others have noticed a felt-like fabric sandwiched between the cab and bed that collects all kinds of leafy debris. If you have that same thing, it could be letting the odour in through the vents behind your seats whenever it gets wet.

It’s worth a look.

 

[FoD]

Here’s a thought Bret…

Others have noticed a felt-like fabric sandwiched between the cab and bed that collects all kinds of leafy debris. If you have that same thing, it could be letting the odour in through the vents behind your seats whenever it gets wet.

It’s worth a look.

Do you remember what thread that was in?

 

[DukeCanBuildit]

Do you remember what thread that was in?

Just looked and here is the link….

https://www.ranger5g.com/forum/threads/carpeted-panel-between-cab-and-bed-holding-water.12630/

The first person to point out the irony, gets a gold star.

 

[FoD]

Just looked and here is the link….

https://www.ranger5g.com/forum/threads/carpeted-panel-between-cab-and-bed-holding-water.12630/

The first person to point out the irony, gets a gold star.

Thanks, sure OP can use the info

 

[AzScorpion]

Just looked and here is the link….

https://www.ranger5g.com/forum/threads/carpeted-panel-between-cab-and-bed-holding-water.12630/

The first person to point out the irony, gets a gold star.

Should've taken his own advise. lol

 

[Porpoise Hork]

Well I did take my own advice and removed the carpet material about 3 months ago. Unfortunately it didn't help with the mildew smell.

 

[Porpoise Hork]

Well the process of elimination with testing for the leak seems to have been successful. Well to a point. I have narrowed the leak down to either the windshield seal or something down in the cowl. I cannot see where exactly it is leaking in because it appears that the water is going underneath the rubberized jute mat that is under the carpet and not contacting the carpet at all. That must why the carpet has always been dry when I checked it. It does not appear to be related to the cabin filter as it is completely dry and does not have any odor associated with it after performing the leak test. The mildew smell initially seems the strongest on the passenger side when first opening it up after it's been sitting for about an hour after the water leak test. Odd thing is I can now detect a faint mildew smell from the center vents when the AC is set to fresh air but hard to detect at all if on recirculate. If I open the driver's window and the AC is set to fresh air the odor gets very strong if I lean out of it when it is not very strong sitting in the truck and undetectable from the vents if on recirculate and the windows open.

So back to the dealership it goes and this time they better be able to locate it cause I'm gonna pour 20+ gallons across the windshield seal and make sure it's good and ripe in there before I take it in... ?

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