So I bought a 89 sport and when it rained I found out something the seller failed to mention. Ponding in the drivers floor board. I pulled the carpet and found the floorboard behind the pedals is plastered with a hard black putty stuff. And water is seeping from behind it. I removed the cowel and looked for the obvious but I see nothing and looks like a hole. I poured a gallon of water in to it but no great flood came throught the weeping spots. It this time I've had a dehumidifier in the cab until in is not weeping water.
I want to fix the leak but before I proceed to tear the putty off I'm looking for input and advise.
Where is the outside leak?
Mahalo,
Castaway

 

 

 

So what I found was there is a fender well panel located under the brake booster that's triangular in shape and is attached to the fire wall under the booster and to the upper part of the outer fender well. Where it meets the fire wall it rusted through. It's designed for the water to run off but there's an area where crud can build up and harbor water. So after cleaning and drying I filled the seam with Geo-seal 2300. I stuck a small piece of flashing on the inside to prevent the sealant from running into the cab while it dries I put a lot of the sealant on and used a two ft long piece of 1" steel banding as a trowel to spread it so the water will now run away from the holes.
In Hawaii Rust Never Sleeps.

 

Thanks for posting. I have a leak and am in the process of hunting it down.

 

I removed the carpet and pad the seats, plastic panels and the floor plugs. I cleaned the dirt from the area under the booster. I caulked the area under the booster with a gun tube of Geoseal 2320. It took about 1 and a half tubes but I built it up to where the water that runs away from the corner. Then I waited a few days for it to harden up a little. I poured water over the area and still had leaks so I worked the sealant into the area with wet fingers. It still leaked but I added sealant to all sides in and out of the electrical jbox where it goes through the firewall. More water revealed less leaks. I sealed the hood cable boot and No leaks. I used a 4" side grinder with a wire wheel to remove All surface rust throughout the cab floorboards. Vacuumed and blasted 100 psi air to remove the ground off rust. Then I had holes under the pedals and a few other places. I applied two coats of Overrust epoxy coating to the entire floorboard. I scuffed that up with a green scotchbrite and applied two coats of Rustolium oil based paint. After two days drying I used 26 gauge aluminum to cover the entire area under the pedals. I applied Byutal sealant to the floor around every hole before I set the new floor panel in place. I used stainless pop rivets every two inches all around the edge. Then I covered all the rivets and the edges on the patch with geoseal and used byutal to fill the cavities on the outside under the patch. I kept my fingers wet with wd40 to prevent the byutal from sticking to my fingers. After a few more days cure time I coated the outside in the fender well with spray undercoat. I did the same to all the area where I applied the geoseal to the firewall, all around the jbox and under the booster. I applied "flashband tape to the small holes around the floor and heated it with a torch to bond it. Then I covered the entire floorboard inside with Hurculiner. A lot of work but a permanent fix