PSA: Check under your door sill trim if you live in the rust belt!!

[ctuan13]

Was doing some in depth interior detailing of my truck before I depart on my cross-country road trip and removed the door sill trim to get all of the dirt, sand and dust cleaned up that had worked its way underneath. In doing so, I discovered something very concerning: Due to an inherent design flaw/oversight, there is pretty sizeable gap between the interface of the curved footwell trim and the flat door sill trim.

Any time water or in the rust belt during winter, salty brine, drips onto this transition zone, it will easily find its way down below. Right below is where one of the main body wiring harnesses runs and there is an enclosed channel along the cab that runs all the way to the rear. There isn't really a way for water to escape once it's down there and thus it'll just sit there until it eventually evaporates.

Despite the frequent misconception, aluminum does corrode, just not usually in the spectacularly destructive way steel does. Well I could see clear evidence of early corrosion as the paint began had already begun lightly bubbling down below. And out of an abundance of caution, because I almost couldn't believe it was all coming from this single point of intrusion, I searched and checked for leaks everywhere else and missing or leaking floor grommets, but it was obvious from the salt residue patterns where the liquid was coming in.

So naturally I wanted to clean it all out and remove the salt as best I could, so I removed the footwell trim and attempted to unclip the brackets holding in the harness. Probably don't do this unless you wanna snap the plastic like I did. I was able to secure them back together with zip ties, but you might have to just try and work around the harness with a fine tip adapter with your shop vac. For me, I used a very damp (dripping wet) microfiber cloth soaked with water to thoroughly dilute and soak up the salt in the area. Once it was cleaned, I dried with a shop towel, I followed up with a quick wipe with ONR (Optimum No-Rinse) wash + wax.

What was my solution? After I reinstalled the footwell trim and zip-tied the brackets back together, I added a small piece of seal closed-cell adhesive-backed foam to that particular low spot in the footwell trim. While I'm sure it's not perfect, it seems to take up 95%+ of the gap, so I'm happy for now!

TL;DR: Design flaw in floot well, door sill trim interface allows salty water to get into a void underneath where it can't easily escape and can lead to corrosion. Problem solved remedied with a piece of adhesive close-celled foam.

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[21st Century Truck]

Good attention to details. Nice! Thanks!

 

[sean7512]

Pittsburgh here as well....will be checking my truck today. Thanks for the heads up.

 

[JMD359]

That’s a known issue w F150 and especially super duty plow trucks . They have a goood amount of wiring harness issues there usually not long after the bumper to bumper warranty expires on heavily used trucks .

 

[chl]

Yes aluminum will corrode, which is why when/if you use AL type wire you have to install it properly to avoid hot spots cause by the corrosion as well as the loosening due to AL's coefficient of expansion/contraction.

My mom owned a townhouse built in the 1970's that my brother lived in which used AL wire for all the branch circuits.

After she passed and we were selling it, I inspected the wiring and outlets and found evidence that a disastrous house fire was in it's future unless I replaced/remediated the AL wire.

I had a contractor come in and install copper pigtails using the special device required on all the branch circuits. USING: the COPALUM parallel splice connector by AMP Incorporated which involves attaching a copper wire to the aluminum wire using a special crimp connector and a power tool, creating a "cold weld". This system is recognized by the U.S. Consumer Product Safety Commission (CPSC) as a permanent and safe way to repair aluminum .

I asked the HOA there and they said there had been several electrical fires over the years - no surprise.

This outlet in the basement had signs of burning. You can see the aluminum gray colored bare ground wire.

AL wire was used for a few years in the 60's and 70's for branch circuits when copper was scarce and expensive...until the problems emerged, fires being the most serious.

 

[Randall Stephens]

Yes aluminum will corrode, which is why when/if you use AL type wire you have to install it properly to avoid hot spots cause by the corrosion as well as the loosening due to AL's coefficient of expansion/contraction.

My mom owned a townhouse built in the 1970's that my brother lived in which used AL wire for all the branch circuits.

After she passed and we were selling it, I inspected the wiring and outlets and found evidence that a disastrous house fire was in it's future unless I replaced/remediated the AL wire.

I had a contractor come in and install copper pigtails using the special device required on all the branch circuits. USING: the COPALUM parallel splice connector by AMP Incorporated which involves attaching a copper wire to the aluminum wire using a special crimp connector and a power tool, creating a "cold weld". This system is recognized by the U.S. Consumer Product Safety Commission (CPSC) as a permanent and safe way to repair aluminum .

I asked the HOA there and they said there had been several electrical fires over the years - no surprise.

This outlet in the basement had signs of burning. You can see the aluminum gray colored bare ground wire.

AL wire was used for a few years in the 60's and 70's for branch circuits when copper was scarce and expensive...until the problems emerged, fires being the most serious.

Did not know this. Thanks for explaining.

 

[Randall Stephens]

Was doing some in depth interior detailing of my truck before I depart on my cross-country road trip and removed the door sill trim to get all of the dirt, sand and dust cleaned up that had worked its way underneath. In doing so, I discovered something very concerning: Due to an inherent design flaw/oversight, there is pretty sizeable gap between the interface of the curved footwell trim and the flat door sill trim.

Any time water or in the rust belt during winter, salty brine, drips onto this transition zone, it will easily find its way down below. Right below is where one of the main body wiring harnesses runs and there is an enclosed channel along the cab that runs all the way to the rear. There isn't really a way for water to escape once it's down there and thus it'll just sit there until it eventually evaporates.

Despite the frequent misconception, aluminum does corrode, just not usually in the spectacularly destructive way steel does. Well I could see clear evidence of early corrosion as the paint began had already begun lightly bubbling down below. And out of an abundance of caution, because I almost couldn't believe it was all coming from this single point of intrusion, I searched and checked for leaks everywhere else and missing or leaking floor grommets, but it was obvious from the salt residue patterns where the liquid was coming in.

So naturally I wanted to clean it all out and remove the salt as best I could, so I removed the footwell trim and attempted to unclip the brackets holding in the harness. Probably don't do this unless you wanna snap the plastic like I did. I was able to secure them back together with zip ties, but you might have to just try and work around the harness with a fine tip adapter with your shop vac. For me, I used a very damp (dripping wet) microfiber cloth soaked with water to thoroughly dilute and soak up the salt in the area. Once it was cleaned, I dried with a shop towel, I followed up with a quick wipe with ONR (Optimum No-Rinse) wash + wax.

What was my solution? After I reinstalled the footwell trim and zip-tied the brackets back together, I added a small piece of seal closed-cell adhesive-backed foam to that particular low spot in the footwell trim. While I'm sure it's not perfect, it seems to take up 95%+ of the gap, so I'm happy for now!

TL;DR: Design flaw in floot well, door sill trim interface allows salty water to get into a void underneath where it can't easily escape and can lead to corrosion. Problem solved remedied with a piece of adhesive close-celled foam.

Does your sill plate have a plastic piece that goes down to fill in most of that channel?

 

[ctuan13]

Does your sill plate have a plastic piece that goes down to fill in most of that channel?

Plastic piece to fill the channel? I mean I'm not sure exactly what you're referring to. Can you tell from my pictures?

 

[ctuan13]

That’s a known issue w F150 and especially super duty plow trucks . They have a goood amount of wiring harness issues there usually not long after the bumper to bumper warranty expires on heavily used trucks .

Yeah I figured it was exactly the same on the standard Ford trucks, too. Honestly what a ridiculous design oversight and what a terrible place to run a critical body harness.

 

[Randall Stephens]

Plastic piece to fill the channel? I mean I'm not sure exactly what you're referring to. Can you tell from my pictures?

 

[ctuan13]

I genuinely don't think that my truck even has that piece, but I'll check it when I get the chance. Either way, I still can't imagine that stops liquids from finding their way past...

 

[Randall Stephens]

I genuinely don't think that my truck even has that piece, but I'll check it when I get the chance. Either way, I still can't imagine that stops liquids from finding their way past...

I don’t think it will stop liquid either. A couple dabs of silicone would probably do the job though.

 

[21st Century Truck]

I just took a look under my driver's door sill. No corrosion or bubbling yet...

Methinks a spray of ol' trusty Amsoil HD Metal Protectant from a can I have left over from coating the underbody last fall will do the preventive trick. The Amsoil MP will spray into crevices, and, the surface being basically flat, will cover the bottom of the trough thoroughly over time and exposure to Summer heat.

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