Rear Cargo Subfloor Cavity - Water Pooling?

[Gnarwgn]

Hoping someone can interpret the following:

1. noticed rear cargo flooring/mat was wet, starting at the tailgate and moving into the vehicle
2. pulled back everything to discover pooled water in the subfloor cavity pictured (or whatever you call this open area?)
3. suspecting roof rack bolts and/or sunroof drains, I have reinstalled/sealed rack bolts, and zipped/cleared the sunroof gutters
4. extracted as much pooled water as I could, water was 'milky' color? Does the weird color hold any clues?
5. currently drying/blowing out cavity with my shop vac in reverse, crossing my fingers that the above has fixed my issue but not feeling super confident...

Anybody dealt with this one before/have any other insights into how water is getting into this location? Greatly appreciate the any thoughts/suggestions/previous experiences/wisdom here!

 

[neoworm]

I f you get under the truck and have a look down there there are a few plastic plugs sealing some pretty large holes to that cavity. Make sure they haven't come out or are actually installed. One of mine was missing and that will allow water into that area. Also I would pull the rear tail lights and have a look in there. That cavity is usually full of dirt and water. If they is enough in there it will spill into the spot you are looking at. there are also plastic drain plugs sealing that spot as well. You can pull them out and actually shove a hose in there to clean it out.

Once you have it clean and dry you can reinstall the plugs and load those areas up with fluid film.

Highly unlikely its coming from the roof but possible I suppose. Doubt it's the rear sunroof drains. If they were leaking or had come off the track it would leak directly onto the headliner and you'd notice that. I would check all those plugs under the truck.

Oh and if your truck is rusty you may even have holes down there.

 

[neoworm]

I have the panels and headliner out of my 100 atm so if you need a pic or two of interior panels and roof let me know.

 

[Gnarwgn]

I have the panels and headliner out of my 100 atm so if you need a pic or two of interior panels and roof let me know.

awesome thanks for the feedback, I wasn't aware of these plugs -

I'll have a look at the plugs and report back. I also suspect its not roof rack related, and the sunroof pan is clear so I don't think thats the issue either.

Also good call on the fluid film, have never used before but seems like a great application.

 

[Gnarwgn]

Ok -

Here are both sides from under the truck - the largest diameter object sits in the middle of the two areas that were holding water. It doesn't seem like this would be the culprit? But anything is possible after 20 years. The other two bolts don't go all the way through, and the third 'hole' doesn't go all the way through.

I'm a little lost for what to do next - going off your comments however - should I opn up the larger diameter seal that runs into the space, spray/dry out, apply fluid film, and then seal everything back up?

Oh also - I removed the taillight housings for a look around and all is dry in there, so i don't think I have an issue in there (yet).

thanks!

 

[neoworm]

Those are just body mounts. The plastic plugs I'm referring to are above that and to the right maybe. You can actually see the plugs from the inside through that hole in your second pic. Maybe confirm the plug is there by looking through the inside hole. It's possible you can't see it from underneath with the stock bumper. It's been a long time since I looked under a 100 with a stock rear bumper.

If those plugs are there and the wells behind the tail lights are dry you may want to check your third brake light (THE ONE AT THE TOP OF THE HATCH). They have a tendency to leak and the water may run down the hatch soak your carpet and eventually end up down in there.

If you remove the panel inside the hatch and then get someone to hit the tail light with a hose you should be able to see if it's leaking.

 

[Gnarwgn]

Gotcha - right, I do see the plugs and they look to be ok.

I’ll check the third brake light next, thanks for the order of operations.

 

[neoworm]

there's a high probability thats its the third brake light..

 

[Gnarwgn]

third brake light it is! Waterfall right into the back after 15 seconds of hose.

now just figuring out how to get that sucker out of there so I can run a bead around it and stick it back in for the time being. Is that a permanent solution or should I look into a new third brake light replacement?

 

[neoworm]

You can seal it it up with silicone and yes it will be a permanent fix. So permanent in fact that it will be a huge PITA to get it off again if you ever need to.

Personally I replaced the light but that's just my style. Glad you got it figured out.

 

[Nyquil556]

You can seal it it up with silicone and yes it will be a permanent fix. So permanent in fact that it will be a huge PITA to get it off again if you ever need to.

Personally I replaced the light but that's just my style. Glad you got it figured out.

How much was it to replace the light and how difficult was the install? Thanks

 

[awesomeissquid]

Just a recommendation, if you want to seal the 3rd brake light the typical product to use is some butyl rope. There is a post about it in here somewhere, but basically you pull the light out and use the rope to seal around the housing and then reinstall it. Easy job, just two bolts from the inside to remove the light.

 

[Gnarwgn]

Thanks again @neoworm , I had a bad feeling inside heading into ski season with a 'mystery leak.' If you ever make it to Issaquah, beers on me!

To answer your question @Nyquil556 - looks like replacements run $40-50. Install is really straightforward, I would give the 'one banana' rating (super easy). You can also plan on somewhat destroying your original housing when you take it out, as you will tear the watertight seal apart and likely snap 2 brittle plastic clips that hinge into the top of the light housing opening. I will be ordering a replacement but in the meantime sealed mine back up with some window/door waterproof sealant, because we are having the wettest fall in the history of the world over here. I followed this:

2001 LX470 - Third brake light housing removal

forum.ih8mud.com

 

[Agent T]

Yesterday I had to access my tool kit. It's been raining here and I found some water on the carpet and running down the access cover to the jack/toolkit storage area. But, even more disturbing was the inch plus of pooled water inside and the wet and rusted tool kit. Apparently, it has been leaking for some time. I placed a couple cups under the drips and have an inch of water in each in just over an hour. I know it's not the 3rd break light leaking. I suspect it's the quarter panel window seal, but maybe the roof rack is leaking. Is there a seal for the roof rack that can be replaced?

 

[awesomeissquid]

Yesterday I had to access my tool kit. It's been raining here and I found some water on the carpet and running down the access cover to the jack/toolkit storage area. But, even more disturbing was the inch plus of pooled water inside and the wet and rusted tool kit. Apparently, it has been leaking for some time. I placed a couple cups under the drips and have an inch of water in each in just over an hour. I know it's not the 3rd break light leaking. I suspect it's the quarter panel window seal, but maybe the roof rack is leaking. Is there a seal for the roof rack that can be replaced?

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It is probably the roof rack bolts, but cant hurt to check the quarter panel window gasket and the mounting bolts that are in the C-Pillar. The roof rack bolts do not have a gasket and they are commonly found loose. The holes open directly to the headliner. Was your headliner wet or just coming down that panel? If you pull the roof rack bolts it is recommended to use some silicone on the bolt threads when you reinstall them to seal the holes.

Your quarter panel windows are fully closed right?

 

[Gnarwgn]

Let me give you everything I know on this based on my recent dive into this general issue, from a variable elimination standpoint:

I first noticed my leak, which was 100% the 3rd brake light, leaking in the tool compartment you have pictured. And rusting out my tire iron. So FWIW, unless you have 100% absolute foolproof reasons to believe its not your 3rd brake light, this is a common failure point (and maybe the most common/).

I also uninstalled my roof rack, added silicone to all 12 bolts, and reinstalled to rule out any of my 12 roof rack holes leaking on me.

I also cleared the two sunroof pan tray gutters out by running a small gauge wire wrapped in plastic that I picked up at Home Depot. They sell it on the same rack that they sell chain, if that helps.

SO - my problem was my third brake light, but I also eliminated the other known roof leak variables. Another issue that I found along the way that may be what you are experiencing is leaks associated with the rear quarter windows, and there is a good string on that subject here that may be helpful to you:

Tips on installing rear quarter window weather seal

forum.ih8mud.com

Good luck!

 

[Agent T]

Let me give you everything I know on this based on my recent dive into this general issue, from a variable elimination standpoint:

I first noticed my leak, which was 100% the 3rd brake light, leaking in the tool compartment you have pictured. And rusting out my tire iron. So FWIW, unless you have 100% absolute foolproof reasons to believe its not your 3rd brake light, this is a common failure point (and maybe the most common/).

I also uninstalled my roof rack, added silicone to all 12 bolts, and reinstalled to rule out any of my 12 roof rack holes leaking on me.

I also cleared the two sunroof pan tray gutters out by running a small gauge wire wrapped in plastic that I picked up at Home Depot. They sell it on the same rack that they sell chain, if that helps.

SO - my problem was my third brake light, but I also eliminated the other known roof leak variables. Another issue that I found along the way that may be what you are experiencing is leaks associated with the rear quarter windows, and there is a good string on that subject here that may be helpful to you:

Tips on installing rear quarter window weather seal

forum.ih8mud.com

Good luck!

Thanks for the quick reply. I replaced the cracked 3rd brake light last weekend, which was leaking. I could see when it leaked down the rear window and into the rear hatch. This is coming from the quarter window area and is running...not just dripping...which makes me think it's not the quarter window seals. It could be the sun-roof, but not the front drain tubes as I cleared them. Not sure how to clear the rear sunroof drain tubes without a taking out the sunroof or headliner.

 

[Agent T]

I stripped the entire interior except for the dash looking for the water leaks that drenched the 2nd row carpet and the rear from the 3rd row seats back. leaks. I now know I had three leaks: 1.) the 3rd brake light was cracked and leaking. 2.) The LH roof rack rear bolts. 3.) Sunroof glass seal. I had over an inch of water in the rear body bolt access holes and almost 1/2" in the rear and 2nd row floorboards. I replaced the 3rd brake light with a new OEM unit a couple weeks ago.

Tomorrow I will try to remove the LH roof rack and see what is needed to seal up the bolts. My big concern with the roof rack R&R is the trim pieces around the mounting base of the roof rack. As one time they were flexible. But due exposure, they are now brittle and faded white. I'm pretty sure they will crumble when I try to remove them. Anyone have any suggestions. I have a 2000 LX470...are the later model year roof racks compatible? I know the design changed in the later years and they appear more durable.

For the sunroof leak, I will most likely have to replace the seal. But, I was going to try to apply weather-strip adhesive or some other type of sealer to see if I can patch it. It's leaking right from the center rear of the sunroof where the seal ends meet. Unfortunately, the drip is not caught by the drip pan. Anyone had success sealing a leaking sunroof seal between the glass and the seal?

 

[Gnarwgn]

Savage! Looks like quite the project. I could be mistaken but I think factory racks are interchangeable for the 100 series. I took my original off my 2001 LC and added a more durable factory rack off I believe a 2003, and had no problems. Also there is at least one guy in mud that has a garage full of them and sells the parts/pieces, I just can't remember his handle.

Unfortunately I'm no help with the sunroof leak, sorry about that. I'm sure I'll cross that bridge someday. While everything is out seems like a good opportunity to add some sound deadening to your floor?

 

[Agent T]

Savage! Looks like quite the project. I could be mistaken but I think factory racks are interchangeable for the 100 series. I took my original off my 2001 LC and added a more durable factory rack off I believe a 2003, and had no problems. Also there is at least one guy in mud that has a garage full of them and sells the parts/pieces, I just can't remember his handle.

Unfortunately I'm no help with the sunroof leak, sorry about that. I'm sure I'll cross that bridge someday. While everything is out seems like a good opportunity to add some sound deadening to your floor?

Thanks for the insight. I’ll start looking for used late model roof rack.

I’m with you on the sound deadening. It arrived today. I’m also adding and updated sounds with front and rear cameras, navigation and Bluetooth.