'97 Civic Coupe - Potential "Backlight" (Window) Flange Seam-Sealer Failure, Water Leakage

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"Backlight" meaning rear window... Do folks have any experience with this? My '97 Civic coupe is pretty cherry; has only about 60,000 miles on it, but of course is now 25 years old. The ravages of time, not mileage...

I have water leak(s) in the trunk.

Honda used comparatively little (and apparently short-lived) brush-on seam sealer on spot welded body lap-seams. Wrapped over edges of the trunk skin have failed seam-sealer, and the trunk would p*ss water out of the cutouts for the rear lamps when opened... Fixed that. Tail lamps had dodgy-looking gaskets. Cut out some closed cell foam material to suit, fixed that. Seam sealer in trunk trough area at top of rear quarters failed... Fixed that...

Prb might be that trough area extends to possibly the rear window flange... and to my way of thinking would need rear window glass removed in order to reapply seam sealer, prime/paint, then have rear window re-set with glass adhesive...

I attach three screenprints (sorry, re the order of same) of a procedure that one fellow followed. Comments?

Has anyone got experience with this issue, or any comments, generally?

If I remove rear glass, I would of course hope to not find Swiss cheese. Expensive- and perhaps uneconomic repair. Mebe NOT go down the rabbit hole of backlight removal????
 

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Have you gotten in the trunk to try and verify the source of the leak? My (at the time) 24 year-old Accord needed a new lid perimeter seal to cure a leak we had.
 
In my experience, tailights are the most common source of trunk leaks. Can you fold the rear seats down and have an assistant hit the back of the car with a garden hose?
 
It's principally condensation on the trunk skin, and zero moisture on the underframing of the trunk. More, around the hinge area. I really think it's the lap seam's seam-sealer, right into the window flange area that is leaking.

As a side comment, maybe it's the environment (quite mild but wet Vancouver) but it's certainly also the sheet metal base material too - but this Honda does not rust at high rates when the paint surface is broken. I've seen many cars where rust blooms, paint bubbles go nuts. Strangely, not this Honda. Maybe I'm dreaming, but I would not be surprised if (if I lift off the backlight) I would not find a badly rusted, pitted, Swiss cheese flange opening. ???
 
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Ahh I see. Stuff was wet in my case along with water in the spare tire well.
That was the case, but no longer. Many things were leaking... Now no longer so. Re the low viscosity epoxy trick, I can't actually see a downside... Can anyone out there? If it doesn't work, the remove-the-backlight action still could occur, no?
 
That was the case, but no longer. Many things were leaking... Now no longer so. Re the low viscosity epoxy trick, I can't actually see a downside... Can anyone out there? If it doesn't work, the remove-the-backlight action still could occur, no?

I was going to mention the high sides of the wheel wells, but you mentioned that. Since I have a 96 Civic, we're very if not exactly similar. First it was the overlap at the top of the trunk opening, in front of the rear window, that needed seam sealer. Then of course the tail lights, mine were leaking on the trunk lid lights. The other one that was weird.. When you take the trunk carpeting (side lining) out, you'll see a support on both sides, holding up the rear deck lid. You would have to go around this to get sealer up on the inner wheel well housing. I found that on the inner side of this support there were leaks. I used seam sealer all around this support where it meets the trunk floor and into the contour around it. BAM! Stopped the leaks.

Just something else to check before pulling the window. Have you removed the back seat and rear trim panels (side, and rear where the speakers are)?? That would give you a better idea of the leak.. if.. it's coming from the seal around the rear window.

Also.. it was never the trunk weatherstripping, mine is even slightly ripped in one spot, still never a leak.. odd, I know!
 
I was going to mention the high sides of the wheel wells, but you mentioned that. Since I have a 96 Civic, we're very if not exactly similar. First it was the overlap at the top of the trunk opening, in front of the rear window, that needed seam sealer. Then of course the tail lights, mine were leaking on the trunk lid lights. The other one that was weird.. When you take the trunk carpeting (side lining) out, you'll see a support on both sides, holding up the rear deck lid. You would have to go around this to get sealer up on the inner wheel well housing. I found that on the inner side of this support there were leaks. I used seam sealer all around this support where it meets the trunk floor and into the contour around it. BAM! Stopped the leaks.

Just something else to check before pulling the window. Have you removed the back seat and rear trim panels (side, and rear where the speakers are)?? That would give you a better idea of the leak.. if.. it's coming from the seal around the rear window.

Also.. it was never the trunk weatherstripping, mine is even slightly ripped in one spot, still never a leak.. odd, I know!
Researcher, your reply is very helpful; thank you! Yes, the '96 and '97 coupe are identical. Great lead, well particularly as regards viewing the window opening from inside the car (passenger compartment)... and quarter windows too, as the lap-seams should be visible, and leakage points may be evident. As I can see where the drips fall on the carpet, this leads me again to the window flange, but the quarter windows could be problematic. Having said this I will also check the internal support framing bases too, as you suggested.

Cheers!
 
I thought I'd add a photo (not of my car, but similar). Too bad the seal is not soldered. My '99 Camry, Japanese built/ two-sided galvanized sheet metal, has its roof seams factory soldered. No roof troughs to rot out and fail. Now, in my view, that's a quality build feature. Trunk trough continues to be seam-sealed though... if memory serves.
 

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I thought I'd add a photo (not of my car, but similar). Too bad the seal is not soldered. My '99 Camry, Japanese built/ two-sided galvanized sheet metal, has its roof seams factory soldered. No roof troughs to rot out and fail. Now, in my view, that's a quality build feature. Trunk trough continues to be seam-sealed though... if memory serves.

yeah there are big differences between Honda's quality and Toyota's! I have the 96 Civic Coupe and a Scion tC. The differences are very noticeable. It's mostly little things that all add up to a better quality. The civic isn't junk but the tC is in a different world in terms of strength. Bolts thicker, better coated for example. And that cheap-not-sealed flange might be your issue. You're welcome for the help!! I just thought that before pulling the glass, which most likely will break being so old (no glass removers are really that gentle as of lately) it would be cheaper to take the interior trim out, which requires the back seat and bottom rear seat cushion to be removed, then the side panels, finally, the rear deck, etc.. But at least you'd know for sure the source of the leak.

You're probably right in your theory, I guess I just like to use the free options up before spending money.. :geek:

And here's another tell tale sign.. is the water from under the trunk lining/carpet? Or from on top? that's how I could tell the rest of the water leak was from under the carpeting. keep us posted on what you find..
 
Maybe I'm dreaming, but I would not be surprised if (if I lift off the backlight) I would not find a badly rusted, pitted, Swiss cheese flange opening. ???
If the backlight was replaced before with an aftermarket or even OEM Honda glass, depending on how careful or careless the person who did the install was, you might find a rusted pinchweld.

The past practice was to use a long knife to cut through the urethane, instead of the OEM recommended method of using piano wire or rope to cut through the urethane. That method can cut a scratch into the pinchweld or the surrounding metal and start the process of rusting. Safelite has banned the use of long knives recently.

The glass adhesive makers(Dow, Dinitrol, Sika) want all cut metal to be coated in a rust-preventative metal primer before the opening is prepped to accept a new windshield/backlight. Of course, most glass techs don’t, but the pinchweld area traps water. If the pinchweld is rusted, they want the appropriate repair done if abrasives don’t reveal sound metal. Again, I’ve seen glass techs merely wipe down the rust with glass cleaner and lay down fresh urethane.
 
If the backlight was replaced before with an aftermarket or even OEM Honda glass, depending on how careful or careless the person who did the install was, you might find a rusted pinchweld.

The past practice was to use a long knife to cut through the urethane, instead of the OEM recommended method of using piano wire or rope to cut through the urethane. That method can cut a scratch into the pinchweld or the surrounding metal and start the process of rusting. Safelite has banned the use of long knives recently.

The glass adhesive makers(Dow, Dinitrol, Sika) want all cut metal to be coated in a rust-preventative metal primer before the opening is prepped to accept a new windshield/backlight. Of course, most glass techs don’t, but the pinchweld area traps water. If the pinchweld is rusted, they want the appropriate repair done if abrasives don’t reveal sound metal. Again, I’ve seen glass techs merely wipe down the rust with glass cleaner and lay down fresh urethane.
I totally agree with you! Matter of fact, if it comes to a car that I really care about, I would seriously consider removing the glass slowly, carefully, with my son in law, after first removing all surrounding interior trim if necessary... I know this may be considered extreme by some, but it speaks to how much I cringe re the whole subject, and the idea of an on-the-clock Tech- or a piecework Tech doing this.

It also speaks to how much I really, really want to preserve, keep the OEM factory installed glass ... if I can.
 
I totally agree with you! Matter of fact, if it comes to a car that I really care about, I would seriously consider removing the glass slowly, carefully, with my son in law, after first removing all surrounding interior trim if necessary... I know this may be considered extreme by some, but it speaks to how much I cringe re the whole subject, and the idea of an on-the-clock Tech- or a piecework Tech doing this.

It also speaks to how much I really, really want to preserve, keep the OEM factory installed glass ... if I can.
hey I agree, if you can remove the glass yourself, DO IT! I'm glad to hear that glass installers are banning the use of those long knives! The rust that caused on my Civic was insane! And you don't know it's rusting, you can't see it!

I'm glad to hear that you'll be doing all the work, like they say if you want something done right, do it yourself!

anyway.. Keep us posted on where you find the leak is coming from..
 
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