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Tue Mar 24, 2020 9:13 am

Who ever does the repair. Be sure that they use no filler on the bonding areas when doing repairs.
Once repairs are done have pinch weld area left in Epoxy primer and not paint and clear coat. You want the best possible bonding surface and bonding an adhesive to clear coat is recipe for disaster.
Encourage your shop to replace as much rusty metal as they can and not just grind the rust clean. Clean rust is still rust.
Consider re installing the glass without the exterior trim molding or using an under side molding in its place. You want to be able to blow out the dirt and crap which fester when left alone.

Stacy

Fri Dec 15, 2023 7:07 pm

I thought I would add my experience here for anyone thinking about DIY'ing rust around your windshield (which is likely due to a poor windshield installation, like mine was). First off, I have never done body work so take what I say with a grain of salt. I learned a lot during this process and I can say that some won't agree with my method. But at least if you are considering tackling this same project here is more information to consider.

First off, I agree with 16CVs replace all the rusty metal you can. Unfortunately for me I have no skill in replacing metal so I was left with dealing with rusty metal.

I'll take you through the timeline which included me learning and changing directions during the process. I knew I didn't want to deal with removing and installing the actual windshield so I made arrangements with my local windshield shop. They were great to deal with. I would touch base with them as the process developed so that when I was ready for the install there were no surprises on either of our parts. I was hoping I could get some of the cost covered by insurance, but my policy required that I fulfill my deductible for windshield replacements which is more than the cost of the replacement, so no help from insurance. Also, I had to take the van to and from the windshield shop, meaning I got to drive without a windshield. I got a few strange glances.

Here's what I was seeing before I had the windshield removed. At first I thought I could deal with this without removing the windshield but all the advice I got was to remove the windshield, then deal with it. There was similar bubbling on the driver side A pillar.

What I discovered is that there was a lot of squeeze out of excess urethane adhesive done by the prior windshield replacement. I believe this squeeze out contributed to a lot of the rust. It was especially bad in the corners. Here is the upper passenger side. The gasket is completely removed so all that black is old and older adhesive.

I was hoping I could just treat the surface rust and be done with it. But I discovered that rust was down in the channel where the gasket normally sits. That meant I had to remove all the old adhesive and start treating the rust. While digging out adhesive I noticed the passenger side A pillar seam had rust so I had to dig out the seam sealer here as well. And you can see that rust went under the original adhesive. This is why you should remove the windshield.

Okay, now all the adhesive is removed and then the grinding starts. It is necessary to grind away as much flaky rust as possible before treating it. I decided to use Ospho. There were also some unrelated issues with the clear coat that I decided to address at this time.

Here is where I started changing my mind. I had learned that Ospho, and many acid treatments, leave behind a contaminant that interferes with epoxy primer. Once Ospho is put on it must be 'neutralized' (a misnomer) before you can put your primer over the top. Interestingly, Ospho says this is not necessary. But the people that make epoxy primer say this must be done. I would believe the coatings people since it is their product that fails when folks follow directions on the Ospho label, IMHO. So, I decided to dig out all of the Ospho converted rust and attempt to get to bare metal as much as possible. It is recommended to use a spot blaster but I don't have one. Instead I used a nail set with a smallish head to dig out everything I could, of course the nail set is ruined now.
As an example here is Ospho converted rust on the driver side A pillar.
I scratched off the surface of Ospho converted rust on the upper blob and you might be able to see the rust powder now exposed. This is typical since Ospho does not penetrate very deep.

I kept digging until I was satisfied. This is what it looked like when I stopped and moved on to the next blob. I couldn't get it out of some of the pits. This where a spot blaster would be great.
Once I completed removing all the Ospho treated rust I could I was finally ready for primer. The windshield folks requested I leave them bare metal to apply their primer in preparation for the adhesive. So, I just taped off a 1/2 inch of the pinch weld before applying my epoxy primer. This is what I ended up using. Another lesson along the way, I first bought 1k clear coat but then learned that 2k is far and away a better choice.
And a close up of the same area I showed above.
And another lesson. Black primer is hard to cover with a base color coat. I ended up running out of red base so I had to make sure that the most noticeable areas, ie A pillar, were well covered. It took me 7 coats to completely hide the black. I then used 4 coats of clear. After letting the clear coat cure for 3 days I took the van to the windshield shop and they installed my new windshield. They were happy with what I did and I was happy with what they did.

To summarize, if you are seeing similar rust around your windshield, remove the windshield and check out the area carefully. You may discover rust has grown under the original adhesive. If so, remove it all, then grind away everything you can. Then use a spot blaster to clean out the pits. If you have the ability, replace rusty metal with new. When you have clean shiny metal cover it with 2k epoxy primer. Use a good base color paint, I am very happy with the color match from ScratchesHappen. Finish it off with a 2k clear coat.

Fri Dec 15, 2023 7:39 pm

Looks you spent time prepping and cleaning. The glass guys made a good call in keeping the metal bare for them. In my experience that repair will hold for 3-5 years. Not trying to be negative just realistic. I've seen these more than a few times.

The unfortunate thing about this is that if the first glass guys had properly prepped and primed the glass when it was replaced this would not have happened.

Every time you wash the vehicle take a hose with a concentrated nozzle and chase the dirt out.

Stacy

Sat Dec 16, 2023 10:31 am

16CVs wrote: Looks you spent time prepping and cleaning. The glass guys made a good call in keeping the metal bare for them. In my experience that repair will hold for 3-5 years. Not trying to be negative just realistic. I've seen these more than a few times.

The unfortunate thing about this is that if the first glass guys had properly prepped and primed the glass when it was replaced this would not have happened.

Every time you wash the vehicle take a hose with a concentrated nozzle and chase the dirt out.

Stacy
I have already resigned myself to the idea that this is now a temporary fix and I will have to revisit at some point in the future. Fingers crossed I get a little longer that 3-5 yrs, but I've done all I can do at this point.

I'm really pissed that this was completely unnecessary if only the first windshield guy did his job correctly. The factory adhesive was damned hard to remove and still well sealed in most places.