Shrinking rear window molding.

My car sat outside for a long time and has a couple of euge gaps after the rear window molding shrunk. Is this a common problem with these cars. I'm pretty sure water is leaking into my trunk through here.

Yes the moulding shrinks over time. You can slow down the shrink with moulding dressing (silicone) but it will still shrink, mine have shrunk too just not as much. The trunk leak would not really come from there, the window is sealed under the glass with urethane. The leak rather would come from the weird body panel fit at the trunk hinges.

Caulking/bridging that moulding gap won' hurt but it will not fix your trunk leak.

I just had a body guy replace the seam sealer on the quarters two weeks ago. Thanks for the heads up that its not the glass. This leak is a pain in the ass.

carguy8888 wrote:

I just had a body guy replace the seam sealer on the quarters two weeks ago. Thanks for the heads up that its not the glass. This leak is a pain in the ass.

Seam sealer won't be enough, especially if Body Guy missed the seam that runs along the top of the rear fenders, and if the trunk hingle landingsare not cleaned and welded or epoxied. .  Look at the area upwards from the trunk floor and you'll see the areas of interest, most likely they will have mild corrosion at the edges.

Yes, it was cracked by the hinges. I can take some pics tomorrow. My plan was to get in the trunk and video where I think it is coming in. Everything is out of the trunk including the mat and the spare tire.

carguy8888 wrote:

Yes, it was cracked by the hinges. I can take some pics tomorrow. My plan was to get in the trunk and video where I think it is coming in. Everything is out of the trunk including the mat and the spare tire.

There is a seam along the top of the rear fender just above the plane of the gutter around the trunk opening. Be sure to check that.

Most likely stopping the water involves removing the trunk and repairing the area where the hinges are secured, as well as getting at those seams. On my car I had the trunk removed and had new metal welded in to hold the trunk hinges.

One almost wonders if the Riv was intended to be a fiberglass or polymer shell. And one wonders about a Riv factory convertible.

I'll post pictures tomorrow of what we did.

I'll snap some pictures tomorrow when I take the car out and you guys can see what we did. Thanks for the good advice of this board I would have thought it was the rear window but the exterior molding isjust cosmetic apparently.

carguy8888 wrote:

I'll snap some pictures tomorrow when I take the car out and you guys can see what we did. Thanks for the good advice of this board I would have thought it was the rear window but the exterior molding isjust cosmetic apparently.

Right.  You do want the rear moulding contiguous because you do not want water/silt/salt accumulating in the cavity, but there's just no communication to the trunk cavity from there.

Consider making sure it is cleaned out (blow out with air after a wash) then fill the gap with black silicone and shape it with a wet Popsicle stick...

Damn, you just reminded me I forgot to take the picture LOL. But apparently I have some more work to do.

albertj wrote:

Yes the moulding shrinks over time.  You can slow down the shrink with moulding dressing (silicone) but it will still shrink, mine have shrunk too just not as much.  The trunk leak would not really come from there, the window is sealed under the glass with urethane.  The leak rather would come from the weird body panel fit at the trunk hinges.  

Caulking/bridging that moulding gap won' hurt but it will not fix your trunk leak.

I use 303 protectant. I like this product since it offers UV protection.

nickwon wrote:

albertj wrote:

Yes the moulding shrinks over time.  You can slow down the shrink with moulding dressing (silicone) but it will still shrink, mine have shrunk too just not as much.  The trunk leak would not really come from there, the window is sealed under the glass with urethane.  The leak rather would come from the weird body panel fit at the trunk hinges.  

Caulking/bridging that moulding gap won' hurt but it will not fix your trunk leak.

I use 303 protectant. I like this product since it offers UV protection.

I use 303 also and it is **great** stuff. Moulding still shrinks.

I had the gap filled behind the black plastic corner piece. It is still leaking alot on both sides. There was a hole just behind the plastic piece but I guess there are more holes somewhere behind it. We did pull up the black strip as well but we missed something. I am glad I did not put the carpet back in yet.  

Just to be clear, the weatherstripping around the rear window( your part that looks like it shrunk, does not keep water out of the trunk. Where you see the hinge in your picture, water is able to get in there normally, it is not air tight. I dont know if you removed it, if it is not attached properly or if it is missing, but you shouldnt be able to see that flat white lip in the bottom right corner of your picture. There is supposed to be a weatherstripping on there that keeps the water out.

Oh, I missing a piece? Can you post a pic so I know what I am missing?

Holy s%$!. That really helps.

Ill say! That would cause quite the leak!

I have quite the leak lol. Is it the rear glass or part of the trunk weatherstrip?

Its the trunk weatherstripping. Its one piece and just wraps around the metal ledge. Seats against the decklid when the trunk is closed

I see the piece that is missing super thank you. GM exploded views only show the oval gasket going around the trunk, not the one I am missing. A stupid question, without that gasket would the water not go just into the channel not in the car? I am going to hunt down this gasket.

Some water will always get into the channel, where the hinges are. There arent any flat spots though so it should run right out by the taillight. Thats why most taillights get those two spots where the chrome starts pitting. The rubber weather strip you’re looking for, keeps that water from splashing into the trunk, if that answers your question?

Your best bet is to find a riv at a pick and pull and grab one. I would imagine it would still be there on any Riv you find. Probably a couple $ max, if they even charge you for it.

The suspense was killing me so I went out to take another look to see what I was missing. Here is a better picture and I do have a trunk weatherstrip. Do you still think I'm missing something?

Nope, that big rubber weatherstripping is what I was thinking was missing. Are you sure its on properly? If you look in the picture I posted, the weatherstripping covers the entire flat lip of the trunk. It looks like you can see about an inch of that lip in your picture. I dont think thats normal.

It is, I felt wetness when I stuck my hand behind the black filler piece but we filled it last week. There must be another area that is open. Sucks.