Definitive 2000-2006 cab-area rain water leak thread

1st GEN CONTENT FOLLOWS!

I was looking to see if anyone had a laundry-list of common fresh water or rain leaks for the Gen1 Tundras but couldn't find a sticky-able centralized source for all leaks to either pin or act as a main reference. I was hoping to go through and check a lot of these to work on proactively - leaks are inevitable, manufacturers rarely design cabins that are rain-proof for the long term.

Since I was pulling the info on my own to start working through these on my '06, I thought I'd do something useful and create a go-to thread. This thread assumes you've checked for obvious stuff, like ... making sure the A/C condensate drain nipple in the engine bay on the passenger's side of the firewall is clear, you're sure this is not coolant, i.e. you're not smelling coolant in the puddle, and you checked some more-obvious sources like roof lights and sunroof drains being clogged (if you have one), sunroof seal.

One tip to add if you're here and troubleshooting rainwater leaks: Classic "Duck" brand packing tape and a water hose is a GREAT combo to isolate a leak source. If you believe it's the 3rd brake light, try taping it over with clear packing tape, then hit it with a hose to see if it's still leaking. If it is, it's probably another source - try taping across the top of the rear window seal now, and test again. If it's still there, maybe tape the roof rack rails from end-to-end and try again. Keep going until the leak stops. A few of us have used the tape trick to rule out possibles, and you can leave the tape on as long as you like. Turtle Wax's sticker and adhesive remover ($6-8/can at any parts store) easily and safely removes any tape residue.

Clearly - and to the point of this thread - other members have found and fixed a few common sources of leaks. Here are the ones I could find, categorized with an explanation, with the most common solutions and part number where applicable and threads linked to it if you want more reading. If anyone has new things to add, I'm not anyone's boss, but it could be cool to add here. If you tag me in your reply, I'll insert your fix into this list when time permits

UPDATE 5/24/2024: Looks like the old cowl fastener video got pulled from YouTube, but on a positive note, some guy created a new video compilation walking thru all the leaks to check, which I'm appending to the end of this reply!




Cowl fasteners (all models) - The plastic fasteners that receive the screws to hold down our black plastic cowl vent cover have a foam seal that breaks down over time, allowing a leak over the blower motor area into the passenger floorboard. Specifically THESE TWO, which the video covers below at the 4m22s mark. This usually manifests during water events like rainstorms and car washes. Toyota replacement p/n for the plastic fasteners with new foams is 90080-18055 (but see this note about recent quality issues!) and can be ordered to replace the existing parts. To fix, you need to remove both wipers, remove the black plastic grille from the cowl via its screws/snaps, find the fastener clips, remove the original cow fasteners and clean out the old gasket material, then either re-seal the original fastener with a marine-grade sealant or replace the part entirely (OEM is $1-2/ea). You'll probably want to buy a couple of the other little white and black plastic snaps helping holding the cowl down, they like to break when you pop up the cowl, more info and part numbers here. Related threads giving advice and showing the clips:

https://www.tundras.com/threads/water-leak.50387/

https://www.tundras.com/threads/dripping-into-the-cab.33888/

https://www.tundras.com/threads/2004-toyota-tundra-water-leaks.28770/



Horizontal-sliding rear window (access cab models) - Drain holes for the slider can get clogged up, but also check the next section 'general rear of cab' for other rear-window possibilities:

https://www.tundras.com/threads/the-4-million-dollar-reinvestment-‘build’-a-chronological-story.46816/#post-1210451



General rear of cab/rear cab corners - First and easiest thing to check is the rubbers around the roof seals for damage like this that could be letting water seep in. Next common offender is the 3rd brake light gasket or the horizontal sliding window seals if you have one, but it seems often some found the drain at the top of the windshield where the black roof rack seals meet the rear window gasket (see here for info/cleaning tips) was clogged or cracked. Pull the roof rack seal up/out where it meets the top of the rear window gasket, check for stuff to clean out, seal seems to be the winner here, if not, the 3rd brake light seal (housing to roof) is the next culprit. Try using clear packing tape across the top seal of the 3rd brake light ... if leaking stops, you know it's the light.

https://www.tundras.com/threads/3rd-brake-light-leak.92739/#post-2364671

https://www.tundras.com/threads/2004-toyota-tundra-water-leaks.28770/

https://www.tundras.com/threads/doublecab-water-leak.36232/

https://www.tundras.com/threads/wha...1st-gen-tundra-today.2558/page-86#post-916108



Windshield Leaks - Doesn't seem to be overly common, but with any vehicle more than 10 years old you may find rust on the sheetmetal which your windshield seals onto or one of the upper three seals (two corner seals, middle horizontal seal) go bad, leading to leaks. This may lead to drip on the dash, the front floorboards, soaking of the visors or headliner, or even weep out of A-pillar trim:

https://www.tundras.com/threads/windshield-leak.22252/

https://www.tundras.com/threads/water-leak-in-cab.35593/



A-pillar leaks - Clips holding A-pillar trim in place could leak, would probably show up around the passenger or driver side kick panel AND is also responsible for electrical issues/havoc when it gets into the fusebox which is extremely common (pics & pics & pics, it happens a LOT!). See the video below, around the 8m45s mark, the problem fastener seems to be the top-most one he's pointing at around the 9min mark. Something to look at if on the driver's side, and cowl fasteners aren't your problem:

https://www.tundras.com/threads/the-4-million-dollar-reinvestment-‘build’-a-chronological-story.46816/#post-1210455



Leaks into the dash - This is a bit of a combo of the above, but we have a lot of people coming to the forum in the last several years with the following symptoms:

• 2 or more totally unrelated circuits failing, like, dash gauge lights and tail lights
• ... or gas pedal gets no throttle and lights stay on in the truck while off
• ... or radio and dash clock stay on all the time but gauge cluster lights won't work
• ... or sudden electrical (or truck not starting) issues during or within 24-48 hours after a rain storm

In that case, I think THIS REPLY covers most of the usual culprits.

In a nutshell: If water is able to get into the A-pillars OR the firewall grommets on either side OR past the windshield sealant at top/sides/bottom of the windshield, the sad truth is, the first wire bundle that water touches is gonna carry that water down into something electrical in the truck. Over time, that'll rot the pins or short the electronics.



Thanks to everyone who posted and-or helped in the threads up there ^^ Knowledge is power.

Here's a great video that walks through all of these, it's almost like he used the info above to create this a couple months ago. He does get into the cowl leaks at 4m22s mark, and touches on the A-pillar leaks at the 8m45s mark. I do have one gripe: He's giving some misinformation about the rear window, the roof trim part. There's actually an intentional drain there on the RC/AC trucks, this explains that a bit better. He does make a mention of this later on. As long as the bottom drain remains open I think maybe you'll be good? But sealing at the top of the channel where the roof seal goes in doesn't give you a place to put the roof rack seal after, eh?

https://www.youtube.com/watch?v=2RZkZNPNcPM#t=4m22s​

 

I noticed evidence of minute rainwater intrusion at the door right above both side mirrors, I traced down the point of entry and found weather stripping attached to the cab had flattened out over the years due to age & compression. The areas are circled in Blue. My solution was to treat the rubber weather stripping with ATP

$21 AT-205 Re-Seal Stops Leaks, 8 Ounce Bottle

AT-205 Re-Seal, this treatment worked and I will periodically reapply ATP to prevent the seal from flattening in the future.

 

Nice thread composition. This should be a sticky!

 

Needs more hand!

 

Someday maybe. I posted a Scooter picture in the other thread.

 

Anyone with a 3rd gen having any issues? Wanting to get ahead of potential leaks before wet season arrives

 

@ColoradoTJ sticky please?

 

My rear window assembly was leaking through the upper driver's side corner. Went to a window place and they said the whole assembly would have to be replaced because it cannot be removed without breaking it.

I was able to get it removed myself and reseal/reinstall. Doesn't leak anymore.

 

Good job! I love it when they say it can’t be done and you end up doing it with success!

 

Nice find. I've got a leak coming in from the top of the windshield and leaking onto the tranny hump and another starting to leak all over the inside of the fuse panel cover located on the kick panel.

I think it might be time to put my thumb up against a windshield chip and see what develops......with the no deductible windshield replacement and all.

 

I’m also trying to find info but came up empty in the 2nd/3rd gen areas. I have rain water leaking onto my driver side footwell under the steering wheel. It only happens during very heavy rain and I can’t figure it out.

 

Here is a link to my passenger side footwell leak repair, only one of the clips needs to be sealed: https://www.tundras.com/threads/the-6-million-dollar-tundra-revival-story.84992/#post-2152337

 

My leak turned out to be something else altogether. I had wet spots in the corners by the rear seat, but none of the techniques here seemed to solve the problem. One day while standing in the rain I observed that the rainwater was dripping down the side of the window seal, and entering the cab through a sizeable gap. After several days of no rain I gently pried back the window gasket and squeezed liberal amounts of black RTV into the gaps (cleaning it up afterward, of course). Voila! No more water in my cabin!!

https://www.youtube.com/shorts/f-XInpcErFc

 

I just found I’m leaking and collecting in rear cab near / behind pass seatbelt. It’s winter, and we’ve been getting a lot of rain this year. With Temps below 30s majority of the time should I wait until warmer weather in spring when everything won’t be so brittle?
Have not found the source of leak

 

Check the rubber bulb seals all the way around the perimeter of the door opening (physically on the cab, not on the door). Look for rips. Some AC owners have found they're not sealing worth a damn back there. Unless you think the leak is coming in higher than that?

You can also dust the wall of the truck inside the "supposedly sealed" area with baby powder to hunt for weep lines.

 

Pretty sure it’s coming in both sides where the roof strip meets the upper window gasket. They’re dried and cracked, lifted off and a space at the window gasket

 

Clear packing tape is your friend. If you're expecting a lot of rain, tape off the gap between the top flange of the door and the roof, so no water can enter at that point anymore. If the leak stops, you know that's the initial entry point of the water.

You just need to make sure there's no alternate way for the water to get to the seal from another spot

 

Pics for posterity sake....

 

Thanks for another good thread, @shifty`. Unfortunately this one may come in handy for me soon. Found some water on mats after a few days of rain. Driver's side, looks like it was coming through the door and under the speaker. I'll have to take a closer look...

 

Check the bulb seal around the perimeter of the cab-to-door opening.

 

Thanks! I'll do that today.

 

Hey. I'm new to the forums here, and also new to fixing cars in general. I think I also have a leak from the rear windshield on my Access cab. What method/tools did you use to take the rear windshield off? And do you have to scrape off the windsheild adhesive before putting it all back together?

Thanks!

 

1st thing to do is to isolate whether it's the rear window, or the 3rd brake light.

easiest way to do that is to get clear packing tape, and tape completely over the 3rd brake light, so it's impossible for water to reach the seams around the edge of the light.

If leaking stops, you need a new 3rd brake light gasket. If the problem continues, you know it's not the 3rd brake light, and you should probably get a weedeater string and clear out the upper channels of the rear window.

The process is outlined here: https://www.tundras.com/threads/wha...-gen-tundra-today.2558/page-1371#post-2797657

But I'll copy-paste so it's also in this thread for leaks:

I noticed this down the inside of the rear window, passenger side, ran my finger thru it to confirm .... yep, at some point a single stream of water leaked in from the outer seal. Guess my rear window drain is/was clogged or overloaded at some point.

​

So I took a minute to clean things out.

If you pop the roof rack seal rubbers from the rear window surround, you can clean the drain. That rear window surround trim is hollow, it actually acts as a channel to route water from the roof rail provisions, around the outside edge of the window trim, to finally exit out of a drain at the base of the window. If you carefully spray water from a bottle into the entry spot I'm showing below, you should see it drain out of a small divot drain you'll find near the bottom corner edge of the rear window trim (see pic). If not, you may want to clean your window surround for drainage. Here's a picture of the drain process, note the drain divot:

​

I sprayed mine with Microban/water mixture, then took some .065 round weedeater line that's helpful with clearing out sunroof drains, and ran it down into the sorround until water was flowing out the bottom nicely.

​

 

Oh - and when you do that process ^^

If the 3rd brake light is taped off, and you see leaking while you clean out the drain channels, you'll know that was your problem. I recommend to keep towels rolled up along the back window while you clean them out, so you can track for leaks and avoid flooding your interior. Mildew getting rooted in your truck is a big problem that's impossible to kill off.

Thing is, those drain channels aren't built to have any buildup in them, just like sunroof channels. If water has any obstruction causing drainage to slow, get backed up, it *WILL* leak to the inside of the truck. If you find yours are clogged, simply clearing them out should provide the intended speed of water flow, not giving it an opportunity to back up.

 

Thanks Shifty! Yeah I have bit of a unique situation. There’s rust buildup that’s happening at the edge of the rear windshield, and the water is for sure coming from that. So I definitely need to pop off the windshield, scrub all that rust off, prime it, and put the windshield back in place.



So how would you guys recommend popping off the rear windshield?

 

Ouch! Yeah, I misunderstood that one, you got a job ahead. @TX-TRD1stGEN would need to give us the skinny on how he got his out. I haven't seen a breakdown on it.

Which window do you have? Solid 1-piece non-sliding, 3-piece manual side-slider, 3 piece auto side-slider, or solid 1-piece vertical slider?

I have the 3-piece power side-slider. I seem to recall it being held in with - I think - either 2 or 4 studs protruding into the cab. IIRC, you remove the inside trim on the left and right, which covers the seat belt pivots to expose the studs, then unbolt to free up the window. But I'm not sure what needs to be done to free up the surrounding seal.