Rust at Top Edge of Firewall/Cowl

[H3ADBANG4L1F3]

Got some rust poking through the seam sealer at the top edge of my firewall. How would y'all tackle this?

 

[H3ADBANG4L1F3]

Digging through my Google Drive I found this post saved by ghetdjc320. I think this is the same issue that he fixed. https://comancheclub.com/topic/67224-project-“tomahawk”/?do=findComment&comment=724821

 

Would I just pull the old seam sealer, sand, prime, and reseal? Can I even reach the other side of that seam?

[Pete M]

I went through this recently with a passenger side and the answer is, no, you can't easily reach the other side of the seal.    I even pulled the hood so I could pull the hinge and still couldn't get access.  there's a stupid piece of metal in there that blocks everything. 

 

 

[89 MJ]

When you get to it, make sure you get it down to bare metal to really be sure to stop it. There will probably be a lot more rust behind the seam sealer so be prepared for that.

[H3ADBANG4L1F3]

43 minutes ago, Pete M said:

I went through this recently with a passenger side and the answer is, no, you can't easily reach the other side of the seal.    I even pulled the hood so I could pull the hinge and still couldn't get access.  there's a stupid piece of metal in there that blocks everything. 

 

 

Could you cut into the cowl and access it from there? I noticed one of the POs cut into mine to seal up the fresh air intake.

[H3ADBANG4L1F3]

22 minutes ago, 89 MJ said:

When you get to it, make sure you get it down to bare metal to really be sure to stop it. There will probably be a lot more rust behind the seam sealer so be prepared for that.

I'm definitely going to get it done completely. Don't want to half-@$$ it and have it come back and bite me in the future. It was already hard enough wrestling with those heater box studs! The good news is that the rest of my firewall looks really clean.

[89 MJ]

That's what I like to hear! Do it once and never need to do it again.

[Pete M]

15 minutes ago, H3ADBANG4L1F3 said:

Could you cut into the cowl and access it from there? I noticed one of the POs cut into mine to seal up the fresh air intake.

 

 

I'm sure I've seen that before somewhere, but this truck isn't mine so I'm not keen on slicing it up.  it lives in georgia and so I cleaned up and treated the inside and then sprayed flex seal on the inside and deemed it good enough to outlive the truck.   up north and with my own truck, I'd probably do more. 

 

But the rust is inside the seam, so there's a limit on what can be done.   you'll never get it all without tearing apart all the panels (and honestly that would likely do more harm than good)

[ghetdjc320]

29 minutes ago, Pete M said:

 

 

I'm sure I've seen that before somewhere, but this truck isn't mine so I'm not keen on slicing it up.  it lives in georgia and so I cleaned up and treated the inside and then sprayed flex seal on the inside and deemed it good enough to outlive the truck.   up north and with my own truck, I'd probably do more. 

 

But the rust is inside the seam, so there's a limit on what can be done.   you'll never get it all without tearing apart all the panels (and honestly that would likely do more harm than good)

If water can make it down in the seam than so can por15 . Jack up the truck so the rusty seam in the cowl sits just a bit lower. Seal off the cowl drain and thin out some por15 (5% dilution with paint reducer). The thin dilution will run down into any place water was accessing. After drying, I'd follow that up with another coat or two of non-diluted por15. If you can reach back in there with a paint brush on an extension that would work too. Also, a thin caulk/paint scraping blade on an oscillating tool works wonders at removing the factory seam sealer and really exposing any rusty areas hidden below. 

[H3ADBANG4L1F3]

Well I pulled the cowl cover and found this mess. Just fantastic work by a PO.

 

After scraping a bit I was able to break it free.

 

 

I suppose the good news is now I have a bit more access to get the POR15 in like ghetdjc320 suggested. Why do people cut metal if they don't want to weld it back?

[ghetdjc320]

Wondering why they cut it in the first place?? 

[H3ADBANG4L1F3]

3 minutes ago, ghetdjc320 said:

Wondering why they cut it in the first place?? 

If I had to guess I'd say they saw some videos of leaks coming from that area in XJs. I think just the later models use a plastic insert with a foam seal that deteriorates over time.

[H3ADBANG4L1F3]

 

 

[ghetdjc320]

Oh my 

[Pete M]

take some good pics of the insides so we can document the innards.   

[H3ADBANG4L1F3]

On 3/14/2024 at 10:32 AM, Pete M said:

take some good pics of the insides so we can document the innards.   

Here ya go Pete. If these don't do it for you let me know!

 

[ghetdjc320]

Seems like it would be a good idea to install a screen over that intake now that I’m looking at it. 

[H3ADBANG4L1F3]

Reduced some POR15 and got it in the cowl. A little messy!

This little squirt bottle was absolutely perfect for the job. Got these for making bait flavors to fish but they've come in handy a couple different times!

Not the prettiest but it's doing the job!

Here you can see it starting to come through into the cab.

Don't be like me, be prepared for the drippage!

[ghetdjc320]

Looking good. That’s exactly what you want. Let that por15 find its way down there just like the water does