Recommend me a sealant for sealing a high top van? Anyone had success stopping one from leaking?

Hi all,

My high top Ford van leaks in the rain. Top is fiberglass. Done by Mobility Works.

It's a slow leak, very hard to tell where it's coming in. I've tried running water over it and can't find it. Yet, every time it rains, I get small puddles in the front corners of the original roof (which is still intact over the cab).

I've been using 3M Marine Sealant 4000 UV. Tried it at least 4 times, it seems to be better, but the issue persists. It's enough to drive you crazy. This van has other issues as you may know if you seen my other posts, but this leaking top is driving me nuts and I'd like to fix it even if I sell the van. 

I think it might be in part because  I (foolishly) just kept applying the stuff over itself again and again without actually scraping and prepping. 

Any suggestions for a sealant that can withstand water and sun, or is the 3M good and I just need to prep it properly? Thx.

I had a top that didn't leak water, but air would get under it and lift it up a bit.  I was able to fix it with 3M WindoWeld and some self-tapping screws.

In reply to CyberEric :

I was going to recommend the 3M 4000 stuff. I'm not aware of anything better for this situation. 

That stuff adheres really well, and stays pliable, so I'd be surprised if the leak is in that vicinity. Maybe if there's a tiny area that doesn't have good adhesion due to oil or some other contaminant?

it's interesting that you only find the leak after rain, and can't replicate it with a hose. Were they particularly heavy or long storms, or does it leak after light showers too? 

You could have it Rhino Lined. They could do the whole roof and seal it tight. Plus tint/paint it to the color of the van

I'd drill a hole where the water ends up puddling - that's your problem - you need holes.

😬

Flex seal spray over ever spot that has a grommet, screw, or opening

Eternabond tape?

That and lap sealant seem to be the solutions of choice. Been doing maintenance on my trailer 

In reply to Apexcarver :

Eternabond tape is amazing stuff.  I was going to recommend that, but I'm not sure how that would look on the side of a conversion van.

In reply to Pete Gossett (Forum Supporter) :

If it rains for 24 hr there's usually some water in there. A light rain, not so much. It's definitely a small leak. Good to know that you would recommend the 3M stuff im using. I want something that stays pliable because im imagining the top flexes and moves ever so slightly over bumps when the chassis flexes and such. 

In reply to wae :

I've considered eterna bond. My concern is getting it flush over a multi layered surface. There's multiple lips where the top meets the van.

Heres a pic of the mess I've made so you can sorta see what I mean. As you can see, looks are not as much of a concern!
 

First off you gotta scrape all that old garbage off.  Get it cleaned up real nice, down to bare steel and bare gelcoat.  Clean it with some acetone, MEK, whatever is your favorite that won't eat the gel coat.

Then look at how the roof is secured.  If it is secured with self-tappers, pull all those out too.

Get a windshield cutting kit and a friend, and cut the fiberglass roof off the van at the sealing surface.  Lift it up on some 2x4 cribbing between the bottom of the top and the top of the van roof.  

Now clean that joint too.

Now dig out the drip rails and do any repair to those that may be needed.  

Now go get yourself some Dicor Lap Sealant, non-self-levelling variety.  Thats OEM for this application.

Apply the Dicor heavily to the sealing surfaces and follow the instructions.  

Reinstall with new stainless steel variants of whatever screws were used to hold the roof on originally.  

Boom.  Problem solved.  

In reply to 93gsxturbo :

I wonder how an oscillating tool would work and if it would eat up the fiber glass too much.

In reply to 93gsxturbo :

Thanks, I really appreciate your input. I have a couple of questions:

1. Have you done this before? It's a big job and I'm wondering how long I should expect this to take.

2. Should I use the Dicor Lap Sealant (non self leveling) on all the seems? There's a piece of vinyl that covers the screws, I'm wanting to put sealant on the edges of that, will the Lap Sealant work well there too? Use it on the drip rails too?

3. How many tubes do you think it will take?

4. After I clean the surface between the top and the body, do I put the top back down and then apply the sealant? Or do I need to apply the sealant then lower it down somehow?

Thanks for any insight!

Spray it with bed liner! 

Bedliner, hmmm.

I'd still need to prep it, I assume. I have no experience with it. And I would not be spraying the whole top because it be got solar panels and such. So it's be just a strip along the seem. There's a part of me that feels uncomfortable with that idea because iver never seen it done and it seems less like the factory way of doing it, but I won't rule it out.

CyberEric said:

In reply to 93gsxturbo :

Thanks, I really appreciate your input. I have a couple of questions:

1. Have you done this before? It's a big job and I'm wondering how long I should expect this to take.

2. Should I use the Dicor Lap Sealant (non self leveling) on all the seems? There's a piece of vinyl that covers the screws, I'm wanting to put sealant on the edges of that, will the Lap Sealant work well there too? Use it on the drip rails too?

3. How many tubes do you think it will take?

4. After I clean the surface between the top and the body, do I put the top back down and then apply the sealant? Or do I need to apply the sealant then lower it down somehow?

Thanks for any insight!

Done it once, was a pain.  Took a whole week picking away at it, needed a few buddies for the lift and the reinstall.  Also need a big place to work on it.  All these rigs are built different and relatively poorly so its tough to say exactly what this particular vehicle needs.  There is a lot of exploratory surgery required even among the same manufacturers.

I would use the Dicor anywhere you are bonding dissimilar materials.  There are plenty of good roof rail tutorials out there, I have not dealt with them yet.  So can't speak to that.

I am not sure how many tubes it will take, I would want 6 tubes so you dont get caught mid-project.  But figure 3-4 to do the job.

Use the sealant between the fiberglass and the steel, then clean up anywhere it smooshs out or looks thing.

I used a windshield cutter - the string on the handles method. Can also just use a piece of small stainless wire and some wooden dowels as handles.  Once the roof is unscrewed it is pretty straight forward to cut the urethane especially if its cruddy.  Gotta be careful with whatever you use to not cut the fiberglass or steel.  I would be  hesitant to use something much more aggressive due to the risk of damage.

You can do a lot of prep before taking it apart.  Interior has to come out around the roof, all that old sealant  needs to be cleaned up, etc.  Plenty to keep you busy.

In reply to 93gsxturbo :

To amend this for a minimum quickie fix:

Perform all of First Step - remove all of external gunk. Clean everything. 
Step Two - Apply good quality gunk, and make as presentable as able. 
Step Three - send it!

lot less effort, for prolly 80% as good!

In reply to 93gsxturbo :

Thanks! When you did it, did you apply the lap sealant before you put the top back down on the van, or after? I'm trying to get a sense for if this is sort of like lowering the top onto a bead of sealant (which sounds really hard) or just sealing the edge once the top is back on the van. 

In reply to 03Panther :

Yeah, I might do this depending on how much energy/time this takes. Thanks.

CyberEric said:

In reply to 93gsxturbo :

Thanks! When you did it, did you apply the lap sealant before you put the top back down on the van, or after? I'm trying to get a sense for if this is sort of like lowering the top onto a bead of sealant (which sounds really hard) or just sealing the edge once the top is back on the van. 

In order to have a clean looking joint I had run masking tape around the perimeter of the steel, so I used that as a guideline.  Apply the sealant to the steel inside the tape lines, set the top down on the sealant, make sure there was a nice even smoosh, clean it up with a gloved finger, then pull the tape up and let the sealant cure.  Just like doing a bathtub.  

May be a candidate for Flex Seal, as seen on TV.

Are you sure the water is not getting in from up higher on the roof?  Maybe through an errant crack or rock chip.  

When I sealed up the transom area of my aluminum outboard boat, I used 3M™ Marine Adhesive Sealant 5200 on some rather large gaps after taping off every edge for a clean look and used this caulk smoother tool to make it look pretty. After about 5 or 6 years, it still looks great.

Amazon.com: Homax Perfect Bead Caulk Finisher, Black

In reply to Noddaz :

I'm 99.9% sure. I don't see water coming down every time if checked it. The only reason I don't say 100% is because I know water can be tricky, but I can literally see it smush out underneath the sealant in the inside, and it's not wet over the top. 

In reply to VolvoHeretic :

Thanks, I like that tool. do you know the difference between the 4000uv and the 5200?