Passenger floor board leak FIX

*This is how I fixed my leak, it worked for me and may be an alternate solution to the Toyota service recall. Attempt at your own risk*

On to my problem:

So after rains I noticed the passenger side floor mats of my truck would be soaking wet. Using the garden hose I was able to find the source of the leak was from within the metal gutter box that housed the windshield wiper motor and linkages. I was getting two steady streams of water originating from somewhere in the dash that came down on the metal wheel well on either side of the metal bracket to the right:

After some research I found this was a common problem for 1st gens and toyota released a service bulletin to fix the problem (I attached the bulletin for reference). Upon reading the instructions, their solution was to basically spray the entire inside cavity with a leak-seal spray and hope to fix the problem.

Not being much of a fan for spray-and-pray techniques for fixing problems, I decided to try and do better. To get a better idea of exactly where the leak was I removed some parts to get better access. Now granted I may have gone a little crazy taking parts off, but thats part of the fun right?

Looking into the gutter where the suspected leak is with the selfie-cam on my phone (the hole is where the wiper motor mounts and protrudes in):

So it looked like the seam where the wall met the base was the only place water could leak so thats what I decided to seal. I decided to use silicon for this job and the tube said it was guaranteed not to crack or peal when exposed to the elements. Plus its temperature rating was something like -60F to 400F so it should be perfect for this situation. In order to reach this seam some interesting engineering took place:

The extension was made from some plastic tubing that fit tightly over the silicon nozzle and was taped to a bent metal rod for rigidity. After emptying 3/4 of the tube onto the seam this was the result:

Granted it wasnt the prettiest fix but it worked! A second water test with the garden hose on full blast led to no water in the cab!
Now with the wiper motor and linkages reinstalled:

Granted I did just complete this fix but we are expecting some serious storms next week so that will be the ultimate test. It survived direct hits from the the garden hose so I'm confident it will be fine.
So thats how I fixed my rain leak and hopefully this information will be helpful for someone else out there.

 

Nice write up!

 

Thanks! Its my first one, thought it was time to contribute haha

 

I liked your write-up and the photos you included, as well as the service bulletin PDF. My 1998 has no leaks. Yet. So I saved the PDF and your write-up just in case a leak starts. Thanks again!

 

I seem to only have this problem with a car wash. Never have in just the rain. Where exactly is the "gutter" your talking about? Is it that part with the big circle hole I'm looking at? (pic of the engine bay) Thanks for the write up. I need to fix this

 

My leak was only noticeable after multiple days of rain and it soaked the carpet, otherwise I never would have found it. That hole you see in the engine bay pic is where the wiper motor mounts and is the same hole you can see in the 2nd to last pic.
I dont know the technical term for it but it acts like a gutter so thats what I called it haha. So if you pop the hood, the "gutter" is on the other side of the sheet metal that the wiper motor is mounted to and under the plastic piece at the base of the windshield, it extends across the vehicle under the black plastic. Here is another pic to help:

The wiper motor is marked with the yellow dot and protrudes into the "gutter". I put silicon all along the seam where the red line is on the other side of the sheet metal inside the gutter.
A good way to check if this is your problem is to remove the wipers and black plastic piece and to put the garden hose into the gutter and look for leaks inside. Let me know if anything is still unclear and good luck fixing your leak!

 

Very helpful post Tacoconqueso. Pictures are worth a thousand words on this one. Did you run the caulking gun through the wiper motor hole or in from the hole in the side where fender was removed?

 

Below the yellow dot in your image is a box with five wires or tubes attached to it. The box also has an orange connector going into the top, and a label with "4WD" printed on it. What is that box do (inquisitive minds want to know)?

 

Is the transfer case/4wd vacuum actuated? I thought they were mechanical?

 

I went in from every opening i could, so behind the fender, the hole for the wiper motor, and especially the 2 large openings on the top on the drivers side. Removing the fender was helpful to seal up some seams accessed from there although im not sure it was really necessary.

That would be the ABS actuator and the tubes are brake lines

 

Duh, I should've known that with the hard lines. My bad.

 

Im going to have to do this

 

Me too. The previous owner had no idea it was happening and there was practically a puddle under the carpet when it rained heavily a couple times this winter

 

I'm gonna give this a shot. My leak cones through the driver side though. This seems to be the only thing that would make any sense though.

 

it appears that removing the fenders gets you a straight shot at the seam. Is it the same for both sides?

 

It depends on the year model of your truck. I have a 1996 and there was no usable access hole once I removed the fender. Well there was a hole but it was offset further than was usable, unlike TacoConQueso's pics. So I had to use a dremel tool to cut an access I could get my hand into. On my truck the leak originated from the seam around the vent tube that is seen in the pics rather than the firewall seam that he caulked. Caulk the fool out of all of it while you are in there. If you caulk the seam as He did and still have the leak, it is likely coming in around the seam on the vent tube that is sticking up. Ask me how I know....

 

if I understand you correctly, the rectangular hole in front of the antenna and behide the firewall is factory, it just isn't really usable for this purpose.

 

OP you said you where expecting heavy rain, did you get any? If so, how did it hold up? I have a leak on the driver side.

 

That is correct. At least on my 1996 Tacoma. In the pics posted by TacoConQueso, his truck had the hole in more functional position. Mine was offset and did not provide a line of sight or serve as a usable access hole. I am guessing the improvement to its positioning was on later models than mine.

 

That hole is factory but it is pretty hard to use for this purpose as there is a corner in there you have to work around. Im not sure if its on both sides but for this job I actually used the two large ports in front of the drivers side the most and they worked well.

Yeah we did, at least I think, it was a while ago. So far it is still holding up with no signs of any leaks. From my research a drivers side leak is much less common but it could be this seam as it runs all the way across if I remember correctly. Either way good luck on it