Does anyone have any videos of repairs done to the seam between the cowl and firewall? I’m having an issue with water in my floorboards and I think I’ve narrowed it down to that. Also am stumped trying to figure out how to take the cowl off.. Any help would be appreciated! Thanks in advance

 

specific vehicle info might be helpful. the 84-88 era (89 for 4runners) water in the floorboards commonly comes from a leaking windshield frame or the gutter around the side windows.

 

Thanks for the reply, Sorry.. It’s a 1988 Toyota pickup 4x4 2 door with solid door windows, I had dang near a book typed out about what was going on with it earlier and my phone decided to delete it so I went with the short version. Anyhow, the windshield is the prime suspect as of right now but I’m concerned about it possibly being the seam where my cowl, fender and firewall meet. (Just because I’ve read that other people are having issues with that and I always assume the worst) I’ve checked my AC drain and haven’t turned my heat on so I figure it’s not my heater core and eliminate of those possibilities. My windshield gasket on the passenger side is basically non existant but I’m having it replaced within the next week so if it continues to leak I’ll know if it’s the seam or not. It’s rained all day today and when I pulled it into the garage to fool around with it I noticed water on the driver and passenger side had water in the upper corners. I’m just looking for a video or a little more information on how the seam repair is done IF I need to do it. Thanks!

 

AC drain already? And I thought today was nice when we hit 55*. Probably your windshield gasket, I wrote a few posts about fixing it here years ago, do a username search.

 

Sunroof?
Drains blocked?

 

Don’t have a sun roof. I checked the AC drain and it was clear. I’m waiting on windshield trim to be shipped then I’m going to have new windshield and gasket put in. I’ll look for your posts. Thanks!

 

https://www.yotatech.com/forums/f120.../#post52000025

 

It is almost always the windshield in those trucks, and about the only way I ever see it fixed is to have a new windshield installed. Not cheap but at least a simple fix.

 

No way man. If you're relying on the installer's bead of polyurethane to seal out water, you're in for more leaks at least 50% of the time. New gasket might slow a leak but will still let enough water in to rot the steel. Read the link I posted above yours. Takes a couple hours and less than $20 to fix it permanently, no new windshield necessary.

 

Most common root cause is rusted through windshield mounting area and/or surrounding, although mine was cause by poor seal in the gutter above the door frame.
You have a gasket, not a chrome trim? In the U.S.A. the gasket or the chrome trim does not seal nor hold the the windshield; it is just superficial trim. If you do not want to remove the windshield for full-pledged rust repair, I suggest you carefully and thoroughly remove the gasket, clean and patch accessible rust spots, and fill gap with Silicone (Dow-Corning 795/995 as, IIRC it does not acetic acid. but rather phosphoric acid that is actually used to convert rust to inactive material), IIRC) as jbtvt did.
I also filled gap on mine after first windshield replacement, but did not do so after second replacement (long story on my thread).

 

Just an update, I got the windshield replaced two days ago with the chrome trim (I’m a sucker for the original look although it may not be the best choice) and am planning on getting silicone to fill any gaps between the trim and windshield. It rained today and I looked just to see if the leak had stopped or not and to my dismay there was water on the driver side floorboards but the passenger side was dry! I’ll take that as a win but now on to checking the seam between the cowl and firewall for pin holes. Will update again when I get it apart!

 

Also check seal on your gutter above doors. That's where my leak came from. Poor design. A gutter should merely be welded on the outside like the A-pillar gutter, so even if seam seal fails it wouls not leak into the interior.