How to Prevent Floor Pan Rust from Spreading?

[kTrainHurricane]

I was driving home today and noticed the driver's carpet was damp. Passenger's floor was dry and the rears were as well. When I got home I looked underneath the car to see if there was any rust on the bottom of the pans. There was a little surface rust and 2 small "almost hole" spots, but nothing drastically bad. I then went in the cabin, lifted the carpet up, and noticed it was pretty wet underneath. There was a lot of surface rust on the top side of the pan, and little rust "chips" all over the place/stuck to the bottom of the insulation layer under the carpet. What is a good way to get rid of this dampness/prevent it from happening again?

I called my mechanic to see if he had a suggestion and he thought it was coming from underneath the car and I should have it sealed (some sort of spray i guess), but I told him I didn't think so because it was dry. He said pull up the carpet and run a fan to dry it, then put Damprid under there. Would you guys agree this is a good step towards getting rid of the problem? Or is there another/better suggestion? Thanks in advance...

 

[kTrainHurricane]

Update:

Right after I made the original post I grabbed a small towel from the garage (about the exact size of area to cover driver's floor pan), lifted up the carpet, and placed the rag underneath it. I figured I would do this to soak up a little water and get rid of the dampness. I drove to the gf's house and came back (elapsed time was prolly about 5-6 hours) and the towel was SOAKED. I mean, I could wring the water out of it, put it back under the carpet and soak up some more. Much worse than I thought. So for now (tonight) I lifted the carpet up and propped it so it is not touching the pan. I figure I will at least let it start drying that way then tomorrow morning I will vaccuum the little rust pieces up and set a hair dryer on it for awhile...

 

[asto-t]

My guess is the windshield is leaking! Thats were I found my problem.Water doesnt travel up and the carpet is rubber base so its not coming through! the old gasket is dried out after all these years! Start by stopping leak first than protect the floors with POR-15 paint kit!

 

[regal81455]

My guess is the windshield is leaking! Thats were I found my problem.Water doesnt travel up and the carpet is rubber base so its not coming through! the old gasket is dried out after all these years! Start by stopping leak first than protect the floors with POR-15 paint kit!

Id have to agree on the leaking part and the coating using por-15 or some similar product however you never mentioned if this was a ttop car, hardtop, or moonroof - you definitely need to address where the water is coming from cuz even if you do coat the floor your car's gonna get a musty smell to it...

 

[1fast6]

this Rust Inhibitor Paint | Stop Rust | Rust Corrosion Inhibitor | Rust Converter
or this POR15, Inc. - Stop Rust Permanently - Repair Gas & Fuel Tanks
Use this when storing the car. It will keep moisture out of interior. Desiccant,Adsorbent,Dehumidizer,Deodorizer,Silica gel,Container

 

[kTrainHurricane]

The car is a hardtop.

I looked up the POR-15 and noticed it was $150. For that price, would I be better off just having the floorpan cut out and have a new piece of sheet metal welded in? I've been told about doing this before on another car project I took some part in. Seems like it shouldn't be too expensive as its an easy job - most of the work is just taking the crap (carpet, console, seats, etc.) out of the car...

Went to Advanced today to browse around. Didn't want to buy anything because I wanna see if its better to have new metal welded in. One idea I was leaning towards was getting this chemical product called "De-Ruster" or something like that. It says it basically "kills" the rust and preps the metal for primer, which would be the next step. Then lastly I would coat it with this 3M spray called "Rubber Undercoating" or something like that. Anyone ever heard of it? Seems like if I sand all the rust away and apply the chemical, the rubber-like coating should seal it up pretty good. Any comments/opinions are appreciated. Thanks again to all those helping me with this!

 

[kTrainHurricane]

Found the Leak

I found the leak - coming from the firewall area. Floors are much worse than I originally thought. Basically the whole thing is shot, just not rusted through (yet). I did not find the exact "hole" where the water is coming through the firewall, but it is pretty high up there. Is there a bezel that is supposed to lay at the bottom of the windshield/towards top of the hood where the windshield wipers are? It seems like the water is coming in right where the wipers are - its like theres a straight shot from that spot into the cabin...

 

[asto-t]

It maybe behind glass? This was my problem

 

[asto-t]

I didnt take picture after the repair but I had the same thing on passenger side. Here it is in primer repaired. I cut out and welded in new metal with very little filler

 

[kTrainHurricane]

Pics - Driver's Side...

Pulled the whole carpet out and here's what I find:

 

[kTrainHurricane]

Passenger's Side

Looks as though the original owner had some sort of towel wrapped in a plastic bag towards the top of the floorboard (pictured). Seems as though its like a barrier to catch the water as it drains into the cabin?

 

[asto-t]

The floors look they need to be replaced or at least the drivers side. You can do this but will be alot of work! Good luck and save this one!

 

[chopped39]

You would not need a $150 worth of por 15 to seal the floors. I would pull the floor plugs get the loose rust cleaned up with wire brush and see what you have to work with. I would cut and patch the small spots and then get 1 qt of marine clean and one qt of metal ready and 1 quart of por 15. 1 quart will cover that whole floor. That stuff goes a long way. The reason for pulling the plugs is you will have to hose out the metal ready. I you go with por15 use gloves and anything it gets on it stays on. Dont ask how I know:biggrin:
That stuff works good.

 

[asto-t]

Helpful Info! Por-15 can be bought cheaper sometimes on e-bay rather than going through por-15 direct

 

[Chuck Leeper]

Fix the leak at the heater box/firewall area...
While U R there, check to see how much water has gotten into the ecm area...

 

[kTrainHurricane]

Fix the leak at the heater box/firewall area...
While U R there, check to see how much water has gotten into the ecm area...

Where exactly in this "area" should I be looking? Anyone have a picture for me? And how do I "fix" the leak?

 

[Chuck Leeper]

U take

Where exactly in this "area" should I be looking? Anyone have a picture for me? And how do I "fix" the leak?

the heater box lid off. The leak is likely at the joint where the box bolts against the firewall. Look there, and U will see hard, dried out, cracked, sealer spread across the joint.
Once the top is off, you will have to chisel the old sealer out, reseal, then reassemble.
Clean the heater core, make sure the seals on the air door are good.....

 

[whitecobra98]

looks about the same as mine did but mine's a t-top car....i replaced both floorans and it doesnt see rain any more

 

[ZNix]

Thats probably what my floors looked like before the completely disappeared! Fix it quick!

 

[turboc87gn]

If it makes you feel better mine are worse than that good luck