510 floor rust. Where is the water from?

[Stitebunny]

I pulled out my carpet to install some sound insulation.  Floors look mostly good.  There is some light rust and it was a bit wet in one spot.  I pulled out all of the factory sound insulation stuff, or whatever it is.  Side note, any one else find a layer of newspaper under that material?  Found a date on the paper from 1967.  English language paper.  Kinda weird.  Anyway, where does the water come from that rusts out these floor boards?  From inside the car, wet shoes, leak etc? Or from outside underneath the car?

There are a couple of holes near the trans tunnel where the trans mount bracket is that are open to the outside.  It wasn't rusty in this area so I'm not positive that is the cause.  My guess is it gets wet from the inside for one reason or another.  

 

[DanielC]

Is not Renton WA close to the Puget Sound?

Has your car ever had foggy windows on the inside, in the morning?

Ever got in your car, with wet shoes, in the rain?

[dr.feltersnatch]

Just about every 510 leaks. Thats why solid floors are so rare

[dr.feltersnatch]

One place that commonly leaks is the center cowel drain. Right between the wipers there is a drain. Its hard to see because ots covered by a metal piece. It will most likely be clogged with leaves and debris. If its clogged water sits in there and will rust it through causing a leak. It drains right on top of the trans. I used a piece of wire and a garden hose to clean it out.

[Stitebunny]

Is not Renton WA close to the Puget Sound?

Has your car ever had foggy windows on the inside, in the morning?

Ever got in your car, with wet shoes, in the rain?

Renton is near Puget Sound and I often get into the car with wet shoes.  Foggy windows on occasion.

 

So your answer is that the main cause of rusted floors is from water being brought into the car from wet shoes?  No doubt about that.  Is it just the thin metal and 40 years worth of wet shoes that has the floors rotting out?

Since I have acquired the car, I have been using rubber floor mats that do a pretty good job of trapping the water from my wet shoes.  I will continue to use them if this is one of the main causes.

 

 

One place that commonly leaks is the center cowel drain. Right between the wipers there is a drain. Its hard to see because ots covered by a metal piece. It will most likely be clogged with leaves and debris. If its clogged water sits in there and will rust it through causing a leak. It drains right on top of the trans. I used a piece of wire and a garden hose to clean it out.

 

Thanks for the idea on that.

I have cleaned that out in the past but will double check that it's clear and if it's leaking or not.

 

I guess I just want to know how to keep the floors from rusting at this point.  They are in great shape and I'd hate to see them get worse if there is something I can do to prevent it.  I have it down to the metal and have treated the small areas of rust and am getting ready to go back together.  I just don't want to overlook something before I get it back together.

 

Thanks for the ideas.

[Draker]

It's either from the windshield.. cowl vents.. rust in the cowl.. random holes in the cowl.. holes in the firewall.

[DanielC]

One way to find water leaks is to remove interior carpet, padding, and othe rstuff, and get in side the car, and hose it down.  but that still does not simulate actually driving the car in the rain.   You could also look for water leaks after a short drive, or have a passenget look around while driving, away from traffic.

 

If you car had a drip rail, on the roof, it is possible the seam is also leaking.  the roof sheet metal is just spot welded on the body every few inches, and after the welding is done, seam sealer is put in the edge of the drip rail, over the joint between the two pieces of metal.  If the seam sealer separates from either piece of metal, you have a gap between the two pieces of metal, and a drip rail to funnel water to the hole.

 

Ideally, if you could park the car in a heated covered garage, it would dry out.  That is not always possible.  But even getting a roof over the car, so rain does not fall directly on the car will go a long way to drying the car out.

[datzenmike]

Water will always seek the lowest level. If the water got in the holes near the cross member seal them up with tar.

 

Here's a tip in cold damp weather. Every time you get out of a warm car leave the door open as long as you can. Thirty seconds is ok longer is better. Warm air will absorb and carry moisture better than cold air. The moisture in the carpeting absorbs into the heater air and when the car cools down it fogs up on the cold windows and drips back and stays in the car. Opening the doors allows this warm humid air to escape and cools down the interior. You'll find less fog or frost on the inside of the windows doing this and the car is actually drying out slightly every time.