Need help determining cause of rust on front floor (1 Viewer)

[93TucsonCruiser]

I have some rust along seams in the front floor pan. The pictures attached are looking up from underneath the truck on both sides. This section of floor angles up towards the firewall (where feet would hit inside if you extended them forward). Not a normal place where I would expect to see rust since it isn't a flat surface where water could stand. There is no rust on the floor pan inside under the carpet other than where it has rusted through from underneath at the seams.

It appears there is a housing attached to the floor on both sides where water/dirt may be getting in. The housing is at the very top in the last picture with the rust hole. There is a small rubber plug at the bottom of both housings. When I removed the plug on one side a lot of dirt came out. How is water/debri getting in there?

 

[baldilocks]

Water from the two front moon roof drains runs down the drain tubes into both rocker panel cavities. There are tiny drain holes in the seem of the body where the rockers are formed. If those drain holes become plugged, the rocker cavity will hold water. There are old threads about using a zip tie to clear those seem drains holes. I removed two of those black plastic plugs that are on the bottom of the rocker facing the ground, the forward most and rear most plugs and left them out in order to be absolutely sure the rocker cavities won’t hold water.

 

[93TucsonCruiser]

Thanks. This is no where near the rocker panels or drain tubes so I am stumped

 

[SNLC]

Body mounts on firewall?

Seen a fair share of JDM 80’s with rust and rot there and only there.

Cheers

 

[SNLC]

Pull your carpet back in the front footwells. Access the body mount bolt and cavity from the round plug about where your feet sit. Look inside this cavity.

Cheers

 

[retlaw]

I cant tell exactly where your pics are. There are two bolts on each inner fender that attach to the firewall. The shape of the inner fender forms a void around these bolts which have sealer around them to keep water from migrating through the bolt holes. Im pulling all of that from memory from when I replaced the drivers fender (outer and inner) so this may not be entirely accurate.