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WoodrowB · 02-16-2019, 11:44 AM

Hello All, 2010 Interstate 3500 Airstream by Thor Motorcoaches.

I have a mystery water drip, damp spot on the ceiling above the drivers seat behind the cab cabinet.

I've removed the cab ceiling bolster and all is dry above the cabinet. I've also removed the little pocket shelf and it's dry above that spot, so is the roof as far as I can reach (not far).

I thought maybe something further back was leaking and running down the ceiling so I removed and re-applied dicor on any seam, cap or screw.

I've read where some people had problems with the roof a/c overflow leaking and flooding the cab but the ceiling inside and around the a/c is dry also (a/c hasn't been used).

I'm wondering if the roof rail bolt has a leak (where I can't see without removing a cabinet). Or there's condensation buildup between the metal roof and sheet metal ceiling and it's just finding it's way to that corner. (I'm in Southern Louisiana, 100% humidity).

I have some Damprid buckets that I keep in the van, but even so, I'm starting to see mildew on the leatherette seats in the back. It's not a lot of water and it appears to be dirty. There's not any more or less water in a heavy rain, when washing the van or when it's dry and sunny.

Anyone have any experience with finding leaks?

Sorry about the pics, the uploader keeps autocorrecting them sideways or upside down.

Thanks

gmillerok1 · 02-16-2019, 05:24 PM

Leaks can be frustrating to track down, but the most obvious place is likely where Airstream penetrated the roof. I have a 2011 Interstate, so the configuration is similar, if not the same.

The first place I would suspect is the vent, which is closest to the area where the leak is showing. It can roll down, and then over above the ceiling. You can remove the light next to the leak and feel around somewhat, but you'd have to catch it at just the right time, as the water may be minimal (enough to soak the mouse fur, but light enough to evaporate off the surface of the ceiling).

The reason I suspect the flange on the vent is because I had a leak in my 2011 around the vent flange. Upon close inspection, the Sika 221 had given way and was loose in an area where a minimal amount of the sealant had been applied and when this area would become full of water when the vehicle was pointed down at the front when it rained, water would seep in. It was not easy to find just by looking, but it took a bit of poking around to find where it was loose to find the area that needed repair. I removed all of the Sika221 from the vent flange, and resealed with new, and that fixed the problem.

The only other area would be the driver's side foot of the solar panel. But I doubt that's the cause.

I also would doubt it has anything to do with the roof rack or MB installed components. Nor would I suspect the AC only because it's so far back and a leak in that area would not likely make it that far.

WoodrowB · 02-16-2019, 05:48 PM

Thanks gmiller,

After I posted I decided to dig back into it. It was hard to find because the ceiling had an extra panel (doing nothing) and the water was hitting just the right spot that the inside of the ceiling wasn't wet but the water was traveling through the two ceiling panels to that corner. (You can see in the one pic of the extra panel hanging by the lights and the water marks)

I removed the extra ceiling piece that was poorly cut to begin with. For anyone interested, the mouse fur trim pops off like a door panel. Some door panel pry tools popped them off without damage and I was able to drop enough of the ceiling sheetmetal to poke around. Even found an old mouse tunnel and turds (I hope it's old).

I'll have to take the vent mount apart. I had just removed the old dicor and applied new but today when I ran water on the roof, I saw the small drip. There's even inside seam sealant (black) and it's coming through that on one of the screws.

Thanks for the response.

Alex AVI · 02-16-2019, 10:57 PM

WOODROWB - Nothing to add to help you. Just wanted to post a Thank You for the details and pics. Great you found where it is coming from. Also, I can empathize - this winter, I have had 4 completely separate & unrelated leaks in the stick house. What a PITA

Not sure why you had the double-ceiling panel. I know mine is not doubled up like that. Curious what the reason was?

InterBlog · 02-17-2019, 06:43 AM

Hello OP from Laf - welcome to the forum. And thanks for your great contribution.

Minor related point - the number of folks on this forum who conceptualize "100% humidity" in the way that we deep-southerners do is fairly small, in my observation. Those who have humidity-related concerns typically do not face our 24/7/near-365 intensity. America is a big diverse country, and that's one of the regional differences that I see manifesting from time to time.

gmillerok1 · 02-17-2019, 09:39 AM

Glad to know I would have been right about the vent had you not already figured that out.

For what it's worth, the only other leak I had was the AC. Airstream had not tightened down the holding bolts adequately, and one morning it rained inside the van until I could figure that out.

The other suspects are the mounting holes for the awning, and the cable pass through on the roof behind the AC unit.

If would be a good idea to inspect these areas and replace with Sika221 if needed.

Alex AVI · 02-17-2019, 01:14 PM

Quote:

Originally Posted by gmillerok1

the only other leak I had was the AC. Airstream had not tightened down the holding bolts adequately, and one morning it rained inside the van until I could figure that out.

GMILLEROK1 - apparently AS did not learn their lesson from your unit because years later, it happened to mine too. Luckily I found it while washing it prior to winter garaging (not during a major downpour). Funny thing was grandson & wife were chilling inside the van on that nice fall day while I washed the outside, when I heard a scream from my wife "van is leaking!" I screamed back "where is it leaking?" As wife tries to figure it out, grandson screamed back "ALL OVER THE FLOOR!" Of course pics below support his answer

WoodrowB · 02-19-2019, 06:47 PM

I couldn't really figure out why that extra panel was added, except someone accidentally drilled all the way up through the roof where the rust spot is. It was easy enough to wipe WD40 on the rust spot and it's not noticeable. There was another cabinet mounting screw that went all the way through the roof also and the water was draining behind the plastic window divider behind the sink and through a plumbing hole in the floor. Both of those holes look as if they were done by Thor because the water spots are old. I had found that one when I first bought the van a few years back.

As for the vent, when I removed it to re seal it completely, I found that the small screws used to mount it were mostly just sitting there so I used larger diam screws putting it back together. Along with Dicor around the base the new screws clamped it down for a better seal.

As for the rear roof penetration, I had sealed that before looking for a leak, which happened to be coming from the rear roof mounted brake light. The roof penetration was just a plate and a lot of Dicor, so I replaced that with a Cable Entry Gland so I don't have to re-seal everything anytime I do any wiring changes (see pic). Which I'm about to do again when I remove the roof tv antenna "dish" which is obsolete. Makes room for a solar panel.

Another entry point which was a Thor design flaw is the black tank vent. If it rains hard enough, water will bounce up into the vent and leak where the abs piping is clamped into the corrugated flex pipe. I'm currently rerouting that in between the shower and the wall (that it's in front of now). There's space for it, I don't know why they opted for that weird grey plastic piece with the shelf.

I've found there's a lot of wasted space on these builds, but that's another story. I need to post pics of what I've done to mine to use those nooks & corners that they just boarded over.

BurntAsphalt · 02-25-2019, 04:22 PM

WoodrowB,
Your post prompted me to inspect that area on our 2011. Sure enough, the mouse fur is stained. Looks like I'll be spending some time resealing the vent as you did. Thanks for your pictures and descriptions of the repair!

BurntAsphalt · 03-17-2019, 01:05 PM

To all my brethren that have repaired their leaky room exhaust vents: We have a Maxxair vent flange which was leaking in our Interstate. Trying to dry out the soaked 1/4" plywood in the space above the aluminum ceiling with a dehumidifier. I want to remove the puck lights to improve drying. I can only pull them down an inch or two and no clip is exposed. Don't want to break them so is there a trick to releasing the spring clips? Thanks

gmillerok1 · 03-17-2019, 01:53 PM

Quote:

Originally Posted by BurntAsphalt

To all my brethren that have repaired their leaky room exhaust vents: We have a Maxxair vent flange which was leaking in our Interstate. Trying to dry out the soaked 1/4" plywood in the space above the aluminum ceiling with a dehumidifier. I want to remove the puck lights to improve drying. I can only pull them down an inch or two and no clip is exposed. Don't want to break them so is there a trick to releasing the spring clips? Thanks

No trick at all. They are simply held in with two spring clips on either side of the back of the light itself (and I should add, very strong springs). Pull them down farther and you will see them on two sides. You can remove them completely by pulling one side down and carefully, while pushing the spring so it will clear the opening. All you have to do is press the springs back in place and poke them up through the hole in the ceiling to replace, and they will snap back into place pulling the light tight. You won't damage them to remove them, but you will scream bloody murder when that spring snaps back and hits your fingers holding on to the light when you remove them completely from the opening, so be careful.

You have a 2011. You should inspect other areas on the roof as the SIKA 221 may be beyond its life for the bath vent, the entry box for the wires behind the AC, the feet for the solar panel, and any where else I can't remember they used it. You will need to remove and replace ALL of the sealant around the Maxxair vent. Simply putting a dab here and there won't cut it for long.

BurntAsphalt · 03-17-2019, 05:07 PM

GMiller,
Thanks for the help and advice to check the whole roof. The bus is in my neighbors garage so I can take the time to remove and replace caulk on all the roof penetrations. I only have one tube of Sikaflex. How many more should I get?

WoodrowB · 03-17-2019, 05:14 PM

I second the "watch out for those springs on the lamps". Those things are like loaded mouse traps.

I also agree about taking the whole vent base apart, clean all the old sealant out and re-seal and mount everything. I did the touch up the first time and it didn't work. Once I took my vent mount completely out I could see why it failed and fixed the problem.

You might consider dropping the ceiling panel partially like I did in the original post. It's possible the insulation is wet and the luan might end up swelling up.

I removed the plastic trim over the sliding door. I had to take a few screws out of the plastic wall shelf to pull down two pieces of the mouse fur trim. They pop out with a plastic door panel type pry tool. The ceiling rivets can be drilled out using a bit slightly larger than the center rivet pin. You can remount it with rivets again, I used wide head self tapping screws.

Question about the SIKA221, is that better than Dicor? Or about the same? I've always used Dicor but I don't like how it collects dirt after awhile and makes the roof look grungy. I've seen some Marine grade sealant/adhesive by Loctite? at the box stores but I have never tried that either. Just curious

WoodrowB · 03-17-2019, 05:41 PM

Here's a follow up about another potential leak spot that I had fixed. Originally, the rear roof opening for the awning, rear camera and tv antenna was just a 1" hole, a lot of sealant and a plastic plate with even more sealant on it.

I replaced that with a cable entry gland (from Amazon). The openings are 3/4" for the penetration seals but I removed them and it just so happens that 1/2" grey flex conduit (box stores) will fit those openings, making everything look way cleaner. While I was at it I painted the plastic awning cover caps.

gmillerok1 · 03-17-2019, 06:27 PM

Quote:

Originally Posted by BurntAsphalt

GMiller,
Thanks for the help and advice to check the whole roof. The bus is in my neighbors garage so I can take the time to remove and replace caulk on all the roof penetrations. I only have one tube of Sikaflex. How many more should I get?

You will use about full tube on the MaxxAir flange. I would think two at the most but the bath vent also can use a lot if it needs replaced as well. I'd start with two, and go from there as they have a limited shelf life (I have an outdated tube sitting on my desk right now). Be sure to completely remove all the old Sika221. The only way is "mechanical" which means, a scraper, and and arm, and muscle. I screwed my left arm up in the process with Lateral Epicondylitis - a fancy word for tennis elbow. It took about 4 months to heal, so take it easy and don't get in a hurry.

Use painters tape outside the border for a much cleaner look. Pull it off before it dries. Don't let it dry without removing the tape or you'll have a mess.

gmillerok1 · 03-17-2019, 06:31 PM

Quote:

Originally Posted by WoodrowB

...

Question about the SIKA221, is that better than Dicor? Or about the same? I've always used Dicor but I don't like how it collects dirt after awhile and makes the roof look grungy. I've seen some Marine grade sealant/adhesive by Loctite? at the box stores but I have never tried that either. Just curious

Sika221 is what Airstream uses for all the roof penetrations. I've not used Dicor, so I can't compare it.

BurntAsphalt · 03-19-2019, 08:08 PM

The ceiling luan plywood was thoroughly soaked and flaking a little around the vent. Did you guys replace any of the wood or is that even a possibility without removing all the shelving? I haven't found any posts on shelf removal so how to do that would be my next question��

gmillerok1 · 03-19-2019, 08:36 PM

Do you mean on the top side? Isn't the bottom aluminum? We caught our leak early and the water didn't cause any issues. If you are talking about the ceiling material around the vent, it would be very difficult to replace it in my opinion as you would have to remove everything that is underneath it.

BurntAsphalt · 03-19-2019, 11:33 PM

Quote:

Originally Posted by gmillerok1

Do you mean on the top side? Isn't the bottom aluminum? We caught our leak early and the water didn't cause any issues. If you are talking about the ceiling material around the vent, it would be very difficult to replace it in my opinion as you would have to remove everything that is underneath it.

Just above the aluminum ceiling in the roof vent area and lights, there's 1/4" plywood layer and then fiberglass insulation below the van's roof. I had assumed that the plywood is under the entire aluminum ceiling but that may not be the case. We had some very heavy rains this past month and both the plywood and insulation got pretty wet where it leaked in and ran along the aluminum panel. I've had a full size dehumidifier running for two days and I can still feel some moisture in the wood. It would be a bear of a job to completely remove and replace the plywood. My concern would be if it delaminates or has gotten mildew/moldy. Really don't want to do that but I'm already halfway there with the ceiling panel loosened for airflow. Thanks

BurntAsphalt · 03-22-2019, 06:56 PM

Quote:

Originally Posted by gmillerok1

You have a 2011. You should inspect other areas on the roof as the SIKA 221 may be beyond its life for the bath vent, the entry box for the wires behind the AC, the feet for the solar panel, and any where else I can't remember they used it. You will need to remove and replace ALL of the sealant around the Maxxair vent. Simply putting a dab here and there won't cut it for long.

GMiller,
I removed all the visible caulk on the roof "devices". The two tank vents have reached the end of their life due to UV damage and will need replaced along with the Maxxair roof flange. I'll probably redo the cable penetration as well like WoodrowB did. On the solar panel and TV antenna feet, did you completely remove the feet before caulking or just leave in place and caulk over the feet?
Thanks