Trunk seal channel rotten! - with Pics
 

I went in to remove my old trunk seal today, and I did not like what I saw. The channel where the seal sits is in fairly bad shape: at the inner right corner, by the right hinge, the channel is totally rotten on the inner side, bottom, AND the outer side. I punched some holes with the screwdriver...

The good news is that the channel still has a structure there, and the rust hasn't totally broke it. The bad news is that the trunk seal won't be able to stop water leakage from the hole on the outer side (i.e., immediately next to the windshield seal).

Here's what I did for now, and this is silly, but I did not have any brighter ideas or any other tools. I cleaned the holes and around them, dressed them with 3M weatherstrip adhesive, and put strips of black electrical tape over the holes.

For now, I installed my new (URO-made) trunk seal without weatherstrip adhesive. Reason? I want to seat the seal and let it deform as it may for a couple days. Also, I need to think about my course of action and figure out how to clean out the rest of the channel - it's got a lot of old weatherstripping sealant on it, which is a PITA getting out. I am resorting to scraping it out because it's so resistant, but I need some kind of a sander, ideally, to clean things up when all is said and done, and then some touch-up paint. After that, I *may* have a chance at a leak-free seal.

I don't know yet how my band-aid fiasco will fare... It looks like the 3M adhesive may be reacting with the plastic in the tape, which means it *may* hold up. But what else could I do there? Find thin strips of metal, lay them over the channel in that spot, and silicone the heck out of them to seal the holes? Anyone know of some sort of "liquid metal" or "liquid plastic" that you can goop on and seal this kind of thing?

P.S. Welding is not an option because I cannot weld, don't have the tools, don't know of any friends who can, and can't afford a body shop at this time.

Call These Nice People
 

They will have an idea or two:

Hey great stuff! I will look into this! Thank you!

I was going to suggest POR also for your fix. I think what I would do is use a paintstripper in the channel to remove the old paint and glue. this way you won`t have to go digging so much and poking holes. just have to be
careful not to get it where you don`t want it.

I have used a lot of POR in the past, and is an excellent product if used as
the directions say.

Marine Clean is a great cleaner degrease.

The metal Ready if kept wet long enough will get you down to good clean
metal, and will etch the metal to give the paint a tooth to bit into.

Use their thin fiberglass sheets to fill the holes and form your channel for
the gasket. put on a coat of the paint, cut the pieces of fiber glass, soak
them good on both sides with the POR. when it is not dry but tacky, might
be the best time to form the pieces to the channel. and then give it
another coat of paint.

All depends how large your holes are, might just paint it, and then add the glass.

they have another product that is their seam sealer. POR Patch. It`s a
filler and seam sealer. after I do my pain work, I use this to fill in the voids
and smooth things out. best think I have found to apply it is an Acid brush.
Then you can work it into seams etc...

Don`t buy it from some auto supply, usually some doofus that knows
nothing about these products. get from a dealer that knows their product.

One thing to remember, this stuff is moisture activated. It takes moisture
to dry it. so do not paint out of the can, dip out what you need and seal the can. also use Seran wrap between the can and lid. any paint in the
groove, and the lid is welded on after it dries. do not shake, only stir with a stick. store the can upside down, it will last longer

I usually buy a 6 pack of the smallest cans. this way there is less waste.
more expensive, but buying larger cans, and having it set up in the can`s expensive too.

Be sure to paint the back side of your rust area also.

charlie

Thanks, Charlie, your write-up is very very helpful.

Basically, a couple of holes are small and could be painted over, while several others are maybe half a dime in size - enough to stick a flat-blade screwdriver and rotate it in place. More importantly the inner wall of the channel is gone at the bend in couple spots, so it will need to be restored.

They have a trunk/floor restoration kit, but I think that includes too much material for my purpose, so I will start with the Super Starter Kit (marine cleaner, metal ready, and por-15).

Now, to repair the channel wall which is partly amiss at the bend... Powermesh Fabric (fiber cloth), "RestoGrip" (thick body filler), or Epoxy Putty? I think the Powermesh would probably need some kind of reinforcement aside from being soaked in POR-15 to act as the channel wall, and might RestoGrip or the Putty be the suitable reinforcement? I am wondering, though, if RestoGrip would work with the Powermesh, or if it is only good to paint over with POR-15.

Let's see if I got this down. 1. Paint thinner to strip the channel and remove any residual glue. 2. Marine Clean. 3. Metal Ready. 4. POR-15 coating. 5. Apply Powermesh and/or RestoGrip or Putty to patch channel wall. 6. Another coat of POR-15 over the patch job. 7. Paint (black, in my case).

I haven`t used the resto Grip, so can`t comment on it. I have used the
Powermesh fabric to bridge some holes under the battery and behind the
R/F fender area, and the end of the rocker. took some work, but came out
pretty good. once the POR dries, it is rock hard.

I removed the back window, and had a rust problem all across the back
under the gasket area. used the Powermesh to seal off the pinch weld
area, and to cover some pin holes. then used the POR patch to build up some low areas, and seal the seams.

Now your channel, I don`t know if the Resto Grip need some backing or
not. Seems like it is like a Bondo filler, but I don`t know. I think the power
Mesh could be formed to work. once it is painted and tied into the existing
good metal, it should be rock hard once the paint dries.

I have used the Epoxy Putty, once that stuff sets up, it is hard to sand
down. that is some tough stuff.

I don`t think paint thinner will strip the channel, I mentioned paint stripper.

Once you get the channel painted and patched up, and the gasket glued
down, you will stand back and be amazed at how talented you are :D.

OH, be sure to wear those mechanic Nitral gloves. that POR doesn`t just
come off easy. It has to wear off. and keep it out of your hair :rolleyes:. don`t
ask :o.

Charlie

Ok, I procured the materials.

What's the word about these things working in 40-F weather? I will have to do this job outdoors, since I don't have a garage. And it's in the upper 30s to low 40s in the near future here in NJ. POR-15 doesn't specifically limit the temperature range, from what I can tell...

I found a one-inch rust spot and half-inch perforation under the trunk-gasket near the right tail-light on my '82 240D. I applied some foil tape to the underside to block the hole and support the repair. Then I lifted as much of the gasket as I dared in order to remove as many rust flakes as possible, before sealing the area with some non-hardening tar-base sealant. Will see how it holds up. May have to try some POR next time.

Happy Motoring, Mark

I would never have thought that our trunk seal channel is such a rotten spot! To be honest, I am not thrilled with MB design of the trunk seal on these cars. Such a vast channel, mostly concealed with the seal, will fill with moisture whenever the seal loses its original design properties. The Saab 900 I used to have had that down - the seal was seated on a ridge, instead of in a channel, and water wouldn't pool as a result - just roll off and dry. Of course, Saab had very different rust problems and somewhat inferior frame metal, perhaps, but that's a different story.

To make you feel better, the 123 has the same channel for the trunk gasket.
Yeah, it`s probably not the best design in the world,
then look at how old these cars are, not exactly spring chickens.

we buy a car that has alot of things neglected over the yrs, and then we
come along to put back in working order.
Just think how boaring life would be with a new car, nothing to do ;).

I was looking through my literature on POR products I have bought. I get a
sheet with ea product on how to use it. the only one that says anything
about temp, is metal ready. "metal Ready will work more efficiently when
used in a temperature range between 65 & 90 deg. Fahrenheit."

With the Marine Clean-- "A hot solution will work better and faster. so
dilute with hot water and store Marine Clean indoors."

That is about it on temperature.
Too bad our temp is so cold there, not fun to work in.

If you can`t get it done in time before the rains, there is always Duct Tape :D.

Charlie

Now that it stopped raining for several days and 2 40F+ days presented themselves, I began the trunk seal channel work. I tackled the more difficult part of the job first - the most rusted areas of the seal channel that need reconstruction.

In my case, that was the right side of the trunk. I scraped off the rust gunk from the previous seal best I could: first with the pry bar blade, which fits perfectly in the channel, then with the wire brush, then with sand paper. I applied a paint stripper, then cleaned with Marine Clean, and finally prepped with Metal Ready. The stripper doesn't seem to be doing too much for me -- maybe because of the outdoor temperature -- so I am still having to do a lot of sanding. I often can't get down to shiny metal, but I am hoping that I've exposed enough of it to make it all stick fine. Plus, there's plenty of rough surface, so hopefully that will be OK.

I painted with POR-15 rust-preventive paint (black) the right-side channel, the bend under the right trunk hinge, and most of the inner channel next to rear windscreen. I then cut pieces of the fiber mesh sheet (from POR-15 guys, too) and laid them over the holes, painting POR-15 gently over to saturate. That seemed to work fine, and the mesh seemed to hold in the paint without letting it run off and drip. Good stuff! Finally, at the bend under the right hinge, where the sidewall of my channel is totally gone, I laid some fiber mesh vertically to bridge the existing metal walls I just painted. I let the paint act as glue to hold the mesh in place vertically, and that seemed to come out alright, although that took quite some finesse. I again saturated the vertically laid piece of mesh with POR-15 paint.

We shall see what comes out of this. I'm letting it dry and set for now.

I am thinking that once my vertical mesh piece is dry and hopefully set in place, I should apply POR-Patch over it, to build up a stronger layer from the "tentative" structure. I might also use some POR-Patch to smooth over the fiber mesh patches I laid on channel floor at various locations, to create a smoother surface for my trunk seal. If that works, I would then paint over POR-Patch with POR-15 again. Like I said - I don't know yet how things have set, or if they have set yet. Drying time is sure to increase in this cold weather.

-Denis

I'm curious whether the fiberglass patch will hold up. Ideally you would use polyester resin or such, with MEKP hardener. If the POR-15 does the job there, it saved you hours.

Ok, it seems that POR-15 has set...

There are some irregularities in how it dried. Maybe I was a bit generous in application, since I was doing it with a brush. First, I thought those were bubbles, but they are too regular, so I attribute it to structure of the channel, i.e., some regularly spaced dips.

On channel floor, it seems my fiber patches held up. My reconstruction of the channel wall is a good starting point. It will not do by itself, but it gives me a solid template, which is what I needed. Tonight, I applied POR-Patch (filler/adhesive) over both sides of my fiber wall. I also applied POR-Patch all over the channel bend by the trunk hinge area, where I had lots of rust holes on channel floor.

POR-Patch is supposed to dry to a rock-hard finish. If all goes well, I may end up with a reconstructed seal channel. It's not going to be perfect, especially since I am completely inexperienced with body work and this is my first (forced) foray into that.

It sounds like you're well on your way!
The only advice I can provide is to take your time and don't take shortcuts on the prep. How things are prepared have a lot to do with the quality of the end product. ;)

I finished repairing and painting my trunk seal channel. I think the seal channel is saved in terms of stopping the rot.

Unfortunately, I encountered some bubbling, both in POR-Patch and POR-15 paint. I think I read somewhere about what may be causing that, probably a misapplication or insufficient surface prep. But since I don't have a garage, I only had 2 days, during daylight hours, to get this done (weather), and I don't have sanders/grinders, so must rely on primitive tools...

I'm not after cosmetics though. The surface for the gasket won't be great on the bottom of the channel, but the sides are looking good... So, hopefully, with plenty of 3M weatherstripping goop, I will be able to install a leak-free trunk seal. I ordered the genuine OE seal from the stealership, since I put in all this work.