roof seam rust repair

Lojack72

Member
While a good short-term solution, I would not consider Eternabond to a permanent fix. I just had to weld the front seam on my '02 158", water had gotten under an edge of the tape I put on 4+ years ago and I had to cut out some rust and weld in a plate. This is second seam I've welded, first was rusted when I bought it. Combination of welding in good metal, marine sealant, and a heavy coat of Monstaliner should finally resolve this.
 

Aqua Puttana

Poly - Thread Finder
While a good short-term solution, I would not consider Eternabond to a permanent fix. ...
:idunno:

Assuming a stable substrate Eternabond has proven to be very permanent on RV roof and other roof repairs. It has worked fine for me on a number of repairs.

vic
 

Midwestdrifter

Engineer In Residence
:idunno:

Assuming a stable substrate Eternabond has proven to be very permanent on RV roof and other roof repairs. It has worked fine for me on a number of repairs.

vic
The biggest issue would be the crappy sprinter paint. The tape is only as good as the bonding surface. I stripped my seams down to primer, and repainted before applying the tape. :2cents:
 

Gaspiper

Active member
I should have mentioned that i used rust primer first then white enamel rust-Oleum paint in two coats , let dry over two days , wipe clean then apply eternabond tape
 

Garryjames

2004 158 Passenger
I'm asking for advice on how to remove/treat the rusted roof joint once most has been mechanically removed.

I'm struggling with how to deal with my roof joint problem. I have an 2004, high roof, 158". The roof joints are rusted and leaking. It seems that the roof joint is just an overlapped, tac-welded joint. The paint on the outside is blistered. There are rust spots in several places on the inside at leak points. I've been reading a lot about how to treat body rust in general but not much on how to deal with rust that has permeated the overlapping roof joint. If there is rust inside the joint, I doubt that it can be stopped, slowed, yes, stopped, no. So my current plan is to use a scaler, then a scraper, then a wire brush, then sandpaper then....? The two alternatives seem to be A) using a "rust remover" based on phosphoric acid etch or B) using a "rust stabilizer" like POR15. C) Use Both. Here are my thoughts on the three approaches.

A) "Rust remover" removes the rust down to bare metal. However, two concerns: 1) will it permeate the joint and remove the rust inside the joint? 2) Will be ever be removed completely by washing? I have a problem with the idea of leaving acid inside the joint. It's electrolytic and, I suspect, will set up a kind of galvanic corrosion after I seal up the outside of the joint, thus causing the next rust outbreak. I thought of treating the joint with etch then trying to pressure wash it out. Then some kind of lengthy drying procedure... Doesn't sound like fun or give me confidence that it will work.

B) Using a rust stabilizer seems reasonable and I feel ok with the idea of leaving some of it inside the joint. However, it has high viscosity and I doubt that it will actually permeate the joint.

C) Use Both: Both doesn't seem to be an option as rust stabilizer doesn't work unless there is rust present. Etch is designed to remove rust.... Unless you remove as much rust as possible then use the stabilizer on the remaining rust. Question: what is the effect of putting stabilizer on top of bare metal? I heard it doesn't work, but can it cause problems with the top coat if it is just sitting there under the primer?

Next step: Prime. Once the rust is either removed and/or partial stabilized, it needs to be at least primed and maybe etched/primed. I'm looking at "Moeller Green Zinc Chromate Primer Outboard Paint" that's supposed to be good in the most corrosive environments, i.e. marine... Any advice on primers? Lots of primers are designed to be sandable. As such, they seem to be porous and weak. This seems to be opposite of what one wants to achieve with a primer, which is impervious and strongly bonded. I don't think that a sandal primer is a good idea. Does anyone have experience with Zinc Chromate or other Zinc primers?

After priming: Paint. Thinking a rattle can of near-color-matching Rustoleum...

After Painting: Taping / Sealing with Eternalbond tape or 3M marine sealant.

Any advice would be appreciated...
 
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Aqua Puttana

Poly - Thread Finder
...
After Painting: Taping / Sealing with Eternalbond tape or 3M marine sealant.

Any advice would be appreciated...
As long as there isn't rust to the point of structural damage that would be my choice.

My limited experience is with repairing my 2004 and a couple other brand roof rust issues. I used sealant prior to discovering Eternabond tape. After wire brushing and priming, the rust has been essentially halted as long as it is covered with sealant or Eternabond tape.

My guess is that those people who have problems with the rust continuing to fester have not really stopped the water leak(s). It is possible that my rust has continued some under the sealant or Eternabond tape, but not enough to be noticed or critical. Without moisture rust stays as is.

Very few people see the roof so some tape or sealant up there shouldn't matter much.

:2cents: vic
 

alexshouse

06' 647 NAG1 3500 HT 158"
I haven't seen a lot of talk about interior rust on the roof seams, so I thought I post about my (still ongoing) experience with it.

The rust on the interior was significantly worse than on the exterior. Just a few spots on the top of the roof seams but the insides looked like this:

https://sprinter-source.com/forum/attachment.php?attachmentid=83265&stc=1&d=1487713402
https://sprinter-source.com/forum/attachment.php?attachmentid=83266&stc=1&d=1487713402

The previous owner had insulated the ceiling so I wasn't sure if condensation was the culprit, but I identified I couple leaks where the seams were separating, which I assume was the problem. There was at least one spot where I could actually see through (this was the middle seam, the seam in back had relatively minor rust in comparison to the other two)

https://sprinter-source.com/forum/attachment.php?attachmentid=83267&stc=1&d=1487713402

So far I've attempted to remove as much of the rust as possible, but the metal underneath doesn't look too pretty:

https://sprinter-source.com/forum/attachment.php?attachmentid=83268&stc=1&d=1487713402
https://sprinter-source.com/forum/attachment.php?attachmentid=83269&stc=1&d=1487713402

The plan from here is to go at it with Rustolem rusty metal primer and then their stops-rust enamel. I'll take Vic's suggestion to tape up the seams on top with Eternabond after I remove the factory sealant and repaint up there, and I plan on plugging up the existing gaps and sealing the seams from the interior with marine sealant as an added measure. I imagine that'll keep everything pretty dry, but I'm not sure if I should be worried about the condition of the metal and whatever rust that remains inside the seams themselves getting worse.
 

Attachments

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alexshouse

06' 647 NAG1 3500 HT 158"
Should be working now. I wanted to include them in the body of the post but messed up the attachments in the process
 

Aqua Puttana

Poly - Thread Finder
... I imagine that'll keep everything pretty dry, but I'm not sure if I should be worried about the condition of the metal and whatever rust that remains inside the seams themselves getting worse.
It's always tough to tell by pictures. I can say that it would take some really bad rust to significantly affect the roof structure. I can also say that even if there is a bit of movement the marine sealant and the Eternabond tape combination should keep things water tight.

I bought a used travel trailer that had suffered water leaks and now has little structure in the one front corner. I cleaned things up and used roof repair mesh, Dicor sealant and topped it all with Eternabond tape. There are no more problems... but DON'T EVER STEP THERE.

vic
 

slowgsr

Member
Grinding the rust out with a 24 or 36 grit disc on a die grinder followed by blasting any pits to clean metal with a sandblaster and glass media works well.

Avoiding spray bomb products as well, I'd use high quality epoxy primer over the newly blasted metal.
 

Aqua Puttana

Poly - Thread Finder
...

Avoiding spray bomb products as well,
...
I agree.

The only time I've had fairly good success with rattle can paint is over non-rattle can primer/prep and multiple top coats of rattle can. Rattle can paint just doesn't seem to have the body/solids as compared to other coatings.

:2cents: vic
 

ocbones

Member
Sometimes the seams from the top may not look too bad until you can inpect the roof from in the cabin. Mines was really bad from the inside. I wire wheeled the rust, por-15, and then eternal bond taped all three roof seams. Eternal bond tape is amazing. good to go! Dicor self leveling lap sealant would work great too.
 

wceatmon

New member
Is anybody running the eternabond tape all the way down to the channels on either side? If so, anyone have a picture? I am wondering what the aesthetics are on this. The seams in my 2006 Sprinter are rusty and leaking and I have some tape in the mail but I am trying to decide if I should run it the entire length of the seam or just up on top. Any info is appreciated.
 

alexk243

KulAdventure
So I just layered on some self-leveling lap sealer while I was up there doing solar and roof-fan as there was no visible rust on top. However there is rust on the inside, similar to the post on this page. Would you guys recommend removing all the sealer, sanding, repainting (por-15) and taping? Or just add more lap sealer?
 

Aqua Puttana

Poly - Thread Finder
So I just layered on some self-leveling lap sealer while I was up there doing solar and roof-fan as there was no visible rust on top. However there is rust on the inside, similar to the post on this page. Would you guys recommend removing all the sealer, sanding, repainting (por-15) and taping? Or just add more lap sealer?
The pictures in post 28 are pretty bad. If they don't get worse... :idunno:

Some (many?) here will disagree with my input.

My experience is that when the external repair properly seals a leak the rusting is basically halted. There can be some continued rust from condensation or other dampness, but if the leak is stopped the serious rusting will also stop. Rust is a somewhat natural preservative coating. Gun barrels on older firearms were "browned" using a controlled rust process. (Of course they were also kept oiled after the process.)

Does the interior rust look like it has affected the structure? If no, I wouldn't be too concerned. Watching it to ascertain it has stabilized doesn't cost anything. Smearing wheel bearing grease on a rusted part often helps to stabilize the situation. (Browning, then oiling. :hmmm:)

:2cents: vic
 

Aqua Puttana

Poly - Thread Finder
So as long as the lap sealer along the seams is sealing the external leak its fine? I am just worried since I will be doing insulation that maybe I should redo the roof seals...
The conservative approach would be to do a full repair.

I suppose an inspection port could be installed to allow periodic inspection of the problem area.

I have used simple blank electrical cover plates and sometimes more fancy marine deck plates in my travel trailer ceiling to keep tabs on areas I've repaired. So far my repairs are fine.

https://www.amazon.com/s/ref=nb_sb_...s&field-keywords=blank+electrical+cover+plate
https://www.amazon.com/Boat-Cabin-Vents-Deck-Plates/b?ie=UTF8&node=3397581

vic
 

Aqua Puttana

Poly - Thread Finder
There are some roof rust pictures in this thread.

https://sprinter-source.com/forum/showthread.php?p=558304#post558304

For the situation in that thread I have no idea whether the outside leaks were properly sealed. That said, from the exterior repair pictures shown in other posts I suspect that the roof was still leaking in from outside.

FWIW. vic
 

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