how to seal this leak?

[Pete M]

pulled the hood for better access and it only kind of worked.   right inside the steel that the toothbrush is pointing at is the leak coming from the cowl and into the cab.  unfortunately there's a steel support inside that is really annoying and blocking good access.  I can touch the corner inside with the toothbrush so I was thinking of scrubbing it as best I can and then hosing the joint down with flexseal coming out of a straw aimed from inside the truck towards that corner. 

 

thoughts? 

 

 

 

 

[Gojira94]

I have the same leak, passenger side only. Been pondering different ways to get at it, and determine the point of entry. I'm convinced it's coming in between the firewall/ blower panel top edge and the forward cowl panel, from road spray or from a lot of parking nose-down. You've done what I've been thinking already- seal that forward cowl panel's seam from the corner in the left of pic 1. I started prying up along that seam about 1/3 of the way across to get in between the pinch welds and clean, squeeze in a spritz of primer, then seam sealer, and re-compressing the seam flat while the seam sealer dries. Water flowing out of the cowl at the ends/ under the fenders shouldn't settle here unless you're parked nose downhill I don't think. It's definitely coming in the top of the firewall/ blower panel, not the side, in my case.

[Pete M]

mine is on the other side of this seem above the hvac hole (where the rust is):

 

 

[Gojira94]

Yep, mine's in the upper right corner, not really along the top of the blower panel. I'm treating both sides for the rust and sealing from the outside like you did.

[Pete M]

well, I sprayed as best I could.  in the coming days I'll find out if I was successful. 

[ghetdjc320]

Use some por15 first if you can. Then see if you can use some brushable seam sealer

[Pete M]

I gave it some serious thought but can't figure out how to get it in the corner without drilling a new big hole somewhere in the cowl.    it's super tight and awkward.   inside the cab (where the rust is) has been sanded down, repainted and will get por-15 over that.  it's a GA truck so I'm comfortable I won't have to revisit it later.  

[Gojira94]

Here's how I'm going about it. One problematic issue is where the upper edge of the "Panel, Dash" joins under the "Panel, Air Chamber" with pinch/ spot welds all the way across. There are gaps in between the welds where parts 2 and 5 come together. Water and dirt settles in the gaps where 5 sags a bit between the welds:

 

 

They're not bad or an issue except for a couple spots. In my case just this passenger end of the join. So what I'm doing is gently prying the layers of 1, 2, 5 apart just enough to get in there and treat the corner issue. Once clean with a coat of POR-15 I'm going to pump in seam sealer from both sides and pinch all the gaps completely flat again and wipe off the excess. With the layers opened up a bit I can get hobby files and a small steel engine brush in the corner gap to get the rust out from the inside:

 

 

 

 

[zomeizter]

3 hours ago, saveevryjp1998 said:

It could just as easily be from none of the above too. It might be from the upper seam along the sides or bottom of the windshield. I've seen several and owned a few that were rusted out bad there and you wouldn't a clue why until you pulled the windshield, cleaned off all the sealant, and found all the rust along the hundreds of spot welds everywhere on that stupid cowl cover. I swear the one I separated was worse than doing an inner and outer bedside. I saved the bastard in my garage. It'll be the last part I ever get rid of. It's a trophy I love to hate at this point.

LOL

[Gojira94]

On 10/11/2023 at 5:24 PM, saveevryjp1998 said:

It could just as easily be from none of the above too. It might be from the upper seam along the sides or bottom of the windshield...

 

I appreciate the experience/ wisdom. I'd like to replace the windshield and go with the later rubber seal since the old chrome strips are the only chrome other than the roof drip rails, and the windshield isn't in great shape. I've never tackled removing a windshield from any vehicle. I'd like to have it out and all surfaces inspected/ repaired and prepped before a glass installer shows up. Good news for this MJ is it's been in NC all its life, now sits 22 min west of where it was sold in 1987. I've had an inspection camera everywhere inside the cowl and this spot is below the cowl envelope, and there's no rust at all coming in from above it, and the inside lip for the windshield is perfect.

[Pete M]

1 hour ago, Gojira94 said:

 

I appreciate the experience/ wisdom. I'd like to replace the windshield and go with the later rubber seal since the old chrome strips are the only chrome other than the roof drip rails, and the windshield isn't in great shape. I've never tackled removing a windshield from any vehicle. I'd like to have it out and all surfaces inspected/ repaired and prepped before a glass installer shows up. Good news for this MJ is it's been in NC all its life, now sits 22 min west of where it was sold in 1987. I've had an inspection camera everywhere inside the cowl and this spot is below the cowl envelope, and there's no rust at all coming in from above it, and the inside lip for the windshield is perfect.

 

it's not a seal, just a trim piece.   be prepared to find some surface rust under the urethane glue of the windshield.  that must be dealt with before trying to glue in the new glass or it won't adhere for long.