Author Topic: Water leaking into trunk  (Read 664 times)

EspriTA350

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Water leaking into trunk
« on: September 24, 2021, 10:21:30 AM »
Hello again TAC. I think before the forum wipe, I was posting about water getting into my trunk. Originally I thought this was the rear taillight gaskets that were leaking. After messing around with replacement gaskets, caulk strip, I was still getting water, so I laid down some newspaper to find out where exactly the leak was coming in. Turns out I was never leaking through the taillights. It's coming through both of the upper corners of the trunk, just before the hinges (where the seam sealer is).

I tried a "quick fix" since I will in all likelihood be getting this car completely repainted within 2-3 years, so it does not have to be pretty. Just has to keep the water out. I have no rust in the trunk yet and I mean to keep it that way. I scuffed the area up and then laid some gray seam sealer down. I did this on the inside and outside of the trunk. Once it dried for a couple days, I then put some gray primer over it and called it a day. This seemed to work for a short period of time, but now I am getting drips again from the same locations.

Upon some research this seems to be a pretty common problem with 2nd gens of both species, Poncho and Chevy.

Is there a better method to repair this for now that a "backyard mechanic" can do on his own? Or is my current strategy doomed to fail again in short order? Right now I'm thinking maybe I should try stripping it down a little more meticulously in the trouble spots, reapply seam sealer, primer etc.


nUcLeArEnVoY

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Re: Water leaking into trunk
« Reply #1 on: September 24, 2021, 01:24:00 PM »
No way you can keep it out of the elements? I never trust the water-guttering engineering on old cars, it's just not as refined as modern vehicles.

Is this something you notice during washes, or do you keep it outside? If it's during washes, try using waterless wash solutions, instead. I probably have a ton of areas that could leak on my '79, but I'd never know about it because I don't drive it in inclement weather and I only use waterless washes to "wipe it down" so to speak, rather than rinsing with a hose.
1979 Trans Am 400/4-Speed W72/WS6 - Starlight Black Hardtop

Gene-73

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Re: Water leaking into trunk
« Reply #2 on: September 24, 2021, 07:45:28 PM »
I would be willing to bet that it's from the window channel as opposed to a seam sealer failure. From the bottom it could be seeping along the seam from the window area. The window channel is a very common place for water to pool and cause rust issues. That area is hidden by the window trim and sometimes the rust is under the glass itself so it's difficult to evaluate without taking a lot of things apart.

One of the previous owners of my 73 tried to "quick fix" this issue by shooting some silicone around the window channel area from underneath. Needless to say it did absolutely nothing to help.

I agree on keeping the car away from water until you are up to repairing this area properly.
Gene


EspriTA350

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Re: Water leaking into trunk
« Reply #3 on: September 27, 2021, 11:15:21 AM »
No way you can keep it out of the elements? I never trust the water-guttering engineering on old cars, it's just not as refined as modern vehicles.

Is this something you notice during washes, or do you keep it outside? If it's during washes, try using waterless wash solutions, instead. I probably have a ton of areas that could leak on my '79, but I'd never know about it because I don't drive it in inclement weather and I only use waterless washes to "wipe it down" so to speak, rather than rinsing with a hose.

It's outside for the time being (will be inside come winter) but I have a good cover for it that fits snug and doesn't blow away during wind. I also have a tarp tied over the trouble spot to help keep water out.

I would be willing to bet that it's from the window channel as opposed to a seam sealer failure. From the bottom it could be seeping along the seam from the window area. The window channel is a very common place for water to pool and cause rust issues. That area is hidden by the window trim and sometimes the rust is under the glass itself so it's difficult to evaluate without taking a lot of things apart.

One of the previous owners of my 73 tried to "quick fix" this issue by shooting some silicone around the window channel area from underneath. Needless to say it did absolutely nothing to help.

I agree on keeping the car away from water until you are up to repairing this area properly.

You could very well be right. The previous owner of my car did repairs to the rear window channel and resealed/reinstalled it, so my first instinct is to write that off as the cause, but it is entirely possible. I unfortunately can no longer locate the pictures of his repair work, but it was by no means a quick fix as in your case. In his words it was leaking before I bought it but the leak became much less pronounced after his repair. I just kept it out of the rain or dabbed the small spots of water in the trunk as needed. With the engine out of the car now, it's much more of a chore to move it back and forth to storage so I have had to resort to MacGuyverisms to protect it.

Wallington

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Re: Water leaking into trunk
« Reply #4 on: September 28, 2021, 10:54:08 PM »
x2 try to find out where it is dripping, or running from, or if only pooling in the bottom. It's fairly clear if the seal isn't that good and weeping there, even then would have to be torrential to get up and over the channel edges. Otherwise could be under the windscreen trim where it sits, finds its way under the glass via the inside or even a pinhole rust spot hidden away. Look around for water staining on or under the parcel tray board or anywhere that water doesn't belong to save pulling the lot apart.
Also, make sure seal is in good condition, facing outwards around the edge of the trunk, sealed along the base of it to the channel floor and with join at the bottom near the trunk lock. If an older seal, also not squashed anywhere. But even an old, bad seal will still seal in light rain. If you have a rear spoiler, check for dampness or rust stains around the underside of the bolt holes where they use a mixture of rubber washers and sealant goop.

Re: Water leaking into trunk
« Reply #4 on: September 28, 2021, 10:54:08 PM »

EspriTA350

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Re: Water leaking into trunk
« Reply #5 on: September 29, 2021, 11:54:16 AM »
x2 try to find out where it is dripping, or running from, or if only pooling in the bottom. It's fairly clear if the seal isn't that good and weeping there, even then would have to be torrential to get up and over the channel edges. Otherwise could be under the windscreen trim where it sits, finds its way under the glass via the inside or even a pinhole rust spot hidden away. Look around for water staining on or under the parcel tray board or anywhere that water doesn't belong to save pulling the lot apart.
Also, make sure seal is in good condition, facing outwards around the edge of the trunk, sealed along the base of it to the channel floor and with join at the bottom near the trunk lock. If an older seal, also not squashed anywhere. But even an old, bad seal will still seal in light rain. If you have a rear spoiler, check for dampness or rust stains around the underside of the bolt holes where they use a mixture of rubber washers and sealant goop.

I already know where it is dripping from, see my opening post please. The seal is fine and I have no spoiler.

NOT A TA

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Re: Water leaking into trunk
« Reply #6 on: October 01, 2021, 11:19:02 AM »
Where it's dripping from and where it's actually leaking in can be quite a ways apart. Rear window channel leaks typically drip from the area under the trunk hinge until they get bad. Often repairs done over the years like the ones done to your car are patches to the lower sections of the window channel like yours. Meanwhile rust (which never sleeps) continues eating away any metal that isn't protected during the repairs AS WELL AS in other areas that didn't appear to need repairs at the time so they weren't repaired or protected. It's not unusual to find a rust hole in the upper corners of the rear window channel especially on the early 2nd gens with the small rear window that originally had a vinyl roof. If you remove the rear window trim (simple cheap tool required) and poke along the entire window channel with an awl you'll probably find your leak.
John Paige
Lab-14.com

EspriTA350

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Re: Water leaking into trunk
« Reply #7 on: October 03, 2021, 12:46:19 PM »
Where it's dripping from and where it's actually leaking in can be quite a ways apart. Rear window channel leaks typically drip from the area under the trunk hinge until they get bad. Often repairs done over the years like the ones done to your car are patches to the lower sections of the window channel like yours. Meanwhile rust (which never sleeps) continues eating away any metal that isn't protected during the repairs AS WELL AS in other areas that didn't appear to need repairs at the time so they weren't repaired or protected. It's not unusual to find a rust hole in the upper corners of the rear window channel especially on the early 2nd gens with the small rear window that originally had a vinyl roof. If you remove the rear window trim (simple cheap tool required) and poke along the entire window channel with an awl you'll probably find your leak.

I understand that I may be chasing the wrong goose. I guess what it comes down to is that I have much less confidence in my own attempt at repair work than the guy who did my rear window channels. There is a significant skill-gap between us with regards to bodywork. That being said, this is a former vinyl-top car. I'll take a poke at it shortly.

The only things I've written off completely as possibilities are the spoiler, since I don't have one, and the trunk seal since that's newer.

NOT A TA

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Re: Water leaking into trunk
« Reply #8 on: October 03, 2021, 09:28:58 PM »
If you've never removed window trim like this before, use a piece of thin cardboard between the tool and window as you work your way around the window so you don't scratch the glass with the tool.  Slide the tool under the trim then slide it till you feel a clip then hook the clip with the point on the tool and gently pry the spring clip a little and gently raise the trim up. Repeat over & over working your way around the window. Be patient!
John Paige
Lab-14.com

Wallington

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Re: Water leaking into trunk
« Reply #9 on: October 04, 2021, 02:31:27 AM »
And already covered, but trunk seal needs to face.outwards from the channel and also be sealed to channel, not just pressed into it.

NOT A TA

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Re: Water leaking into trunk
« Reply #10 on: October 04, 2021, 09:49:44 AM »
also be sealed to channel, not just pressed into it.

I'm going to disagree with this ^^^.   I've never glued them in and didn't ever have one leak. The design of the channel is such that if there was no gasket and you poured water in the channel up by the rear window it would run around and drain out the bottom on the outside of the tail panel. Theoretically with a seal in place and the trunk closed the only way water could get in the trunk would be if the seal didn't touch the trunk lid AND you used a high pressure hose.

If they're not glued in you can pull it out and clean inspect the channel. Gluing them can create little pockets where dirt settles in and holds moisture. Dirt holding moisture is what caused a lot of them to rust in the first place.
John Paige
Lab-14.com

Wallington

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Re: Water leaking into trunk
« Reply #11 on: October 04, 2021, 09:32:50 PM »
Yes, I'll agree with that synopsis. Mine hasn't even had a trunk seal in 10 years.

Re: Water leaking into trunk
« Reply #11 on: October 04, 2021, 09:32:50 PM »
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