Community Forums

jwhalen457 · 10-22-2015, 11:24 AM

The seal between my class C cabover and the top of my cab has deteriorated. It was a caulk seal. From what I have read so far is that silicon caulk will not adhere well to fiberglass but a product called Flex Shot will. Two questions: 1. How have other Class C owners dealt with this problem? 2. Has anyone had experience with Flex Shot in this type of application?
Thank you.

grumpy0374 · 10-23-2015, 03:58 AM

Don't ever use silicon to use as a seal caulk, especially at such a crucial joint. You will never get anything to adhere to it again. It is not made for that type of application.
Don't know about Flex Seal other than what's on TV. That being said, usually when a product like that is pushed like Flex Seal is, it's too good to be true. Personally, I would never trust it to be a good seal.
Tried and true...Dicor caulk, either self leveling for flat areas, and regular non sag for vertical surfaces. Pretty much the caulk that all the rest try to measure up too.
If your really worried about the seam, after the Dicor sets up you can apply some Eternabond tape over it. If done right, it's a one time repair and that seam will never ever leak.
Just search for Dicor and Eternabond on the site.
Grumpy

SoFloRV · 10-26-2015, 06:09 PM

Dicor is probably the best as grumpy mentioned but I wouldn't use the self leveling on a joint as you mentioned. The non sag has a little more body/consistency. The self leveling is good for filling in holes and other non stress or non pressure areas.

I'm beginning to shop more and more at marine boating stores and websites. They have some super sealers and adhesives for fiberglass, wood and practically any other material you would find on a boat. The boats take a beating combined with salt water and I personally think their marine products are more durable and longer lasting than RV stuff. The latest I used was 3M Marine Adhesive Sealant. I like the Fast Cure 5200. You might check it out on the internet..

jwhalen457 · 03-12-2016, 09:03 AM

Quote:

Originally Posted by jwhalen457

The seal between my class C cabover and the top of my cab has deteriorated. It was a caulk seal. From what I have read so far is that silicon caulk will not adhere well to fiberglass but a product called Flex Shot will. Two questions: 1. How have other Class C owners dealt with this problem? 2. Has anyone had experience with Flex Shot in this type of application?
Thank you.

Below is the factory response. Does any one have experience in accessing the space under the cab over bed?

Good morning Jim,
I apologize for not getting back with you on this. Here is what we use on your coach:
CAULK, G2300MHRV-HAPS FREE, CLR HAPS FREE 2300 CLEAR SEALANT
Thank you,
Brandon Tom
Customer Service

Good morning Mr. Whalen,
The cabover is screwed into the truck cab. I’ve seen some issues where they didn’t use enough screws or some of them didn’t grab properly. You can add in more if it is flexing for you. Unfortunately I don’t have a diagram or drawing that shows that.
Let me know if you have any more questions.
Thank you,
Brandon Tom
Customer Service

wendyjr · 03-16-2016, 11:28 AM

is there anything to wrap the cabover in? I have applied eternabond all around but somehow water is still getting in.

SoFloRV · 03-26-2016, 01:49 PM

Wendyjr, I am just finishing a total overhaul of my front cap, 2005 Thor. Unknown to me my class-c had major water issues before I bought it. Once I started pulling off the front gel coat piece I was faced with rot and mold on the entire front nose piece. I could see where a lot of water had come in around the front and 2 small side windows so I eliminated the front window just as most mfg's have done in recent years and removed and resealed the side windows.

After replacing a lot of the wood on the aluminum frame, clearance lights with LED's and some insulation I reinstalled a new gel coat front piece minus the window and used Eternabond 4" tape on all corners of the nose piece from top down and across the horizontal seam outside the cab doors to the coach box. From there I also used the Eternabond on the vertical coach seams directly behind the cab doors. Made 2" angle PVC cut from a 4" X 4" X 6' PVC post covers and covered all the Eternabond seams with the PVC for added protection of the Eternabond. I used just enough ss screws to hold the PVC in place and then used Decor non-leveling caulk to go around all the PVC covers. The side seams will never leak again.

Pay close attention the the top and bottom exterior seams where I found both had allowed water to get through. Now I'm finishing the interior part of the cab over. If water got through from the outside then you most likely have rotted/moldy wood on the interior. I removed the bunk platform wood floor, one side wall cover and the entire ceiling piece which uncovered a lot of rotted wood and mold. All rot and mold has been removed and treated with a mold block spray and painted with mold/mildew primer.

Now all I have to do is put things back together with some modifications.

tiger275 · 03-27-2016, 09:10 PM

Quote:

Originally Posted by SoFloRV

Wendyjr, I am just finishing a total overhaul of my front cap, 2005 Thor. Unknown to me my class-c had major water issues before I bought it. Once I started pulling off the front gel coat piece I was faced with rot and mold on the entire front nose piece. I could see where a lot of water had come in around the front and 2 small side windows so I eliminated the front window just as most mfg's have done in recent years and removed and resealed the side windows.

After replacing a lot of the wood on the aluminum frame, clearance lights with LED's and some insulation I reinstalled a new gel coat front piece minus the window and used Eternabond 4" tape on all corners of the nose piece from top down and across the horizontal seam outside the cab doors to the coach box. From there I also used the Eternabond on the vertical coach seams directly behind the cab doors. Made 2" angle PVC cut from a 4" X 4" X 6' PVC post covers and covered all the Eternabond seams with the PVC for added protection of the Eternabond. I used just enough ss screws to hold the PVC in place and then used Decor non-leveling caulk to go around all the PVC covers. The side seams will never leak again.

Pay close attention the the top and bottom exterior seams where I found both had allowed water to get through. Now I'm finishing the interior part of the cab over. If water got through from the outside then you most likely have rotted/moldy wood on the interior. I removed the bunk platform wood floor, one side wall cover and the entire ceiling piece which uncovered a lot of rotted wood and mold. All rot and mold has been removed and treated with a mold block spray and painted with mold/mildew primer.

Now all I have to do is put things back together with some modifications.

Wow this is great information. Do you have a thread where you are tracking progress on this rebuild? I would love to see some pictures as I am about to have to do a complete tear off and rebuild of everything forward of the rear cab wall. Where did you get a new fiberglass cap? etc, etc, etc. Lets just start with pics if you have them.

Mich F · 03-27-2016, 09:33 PM

Quote:

Originally Posted by tiger275

Wow this is great information. Do you have a thread where you are tracking progress on this rebuild? I would love to see some pictures as I am about to have to do a complete tear off and rebuild of everything forward of the rear cab wall. Where did you get a new fiberglass cap? etc, etc, etc. Lets just start with pics if you have them.

Here's one of many places where you can buy filon
6663 - Fiberglass Siding Cut To Length - Price: $25.00 - Factory RV Surplus - 1611 W Bristol St, Elkhart, IN 46514 (800) 325-1461 (574) 262-3327

You should also check with any local RV repair places, who might sell you the material you need. The freight charges on this stuff could be as expensive as the material.

S Bradley · 04-01-2016, 06:18 PM

If you are still getting leaks? This is a possible solution, I have used to seal hidden leaks.
Find a strong fan that will just fit a window opening; seal it into the window. You are going to create a vacuum inside the RV to pull the smoke in. Purchase a smoke cartridge from an HVAC shop, they are non toxic. With all the openings of the RV closed except the one with the fan, one person outside with the smoke and one inside to find where it comes in. That will help you find where to add sealing product.

You can also just create the vacuum and apply another coat of sealer across the entire opening and let the vacuum pull the sealer into the leak, kind of hit or miss but it might work.

One other thing, I use painters tape to create a nice clean line for the sealant and eliminate some of the cleanup work.

Capt Dan · 05-17-2016, 07:16 PM

SoFlo, I'm about to start the same thing on 2004 Majestic. Feeling overwhelmed, but your info helped.

davephoto · 09-25-2023, 08:09 AM

I'd like to find out what the factory used to seal the top of the U-channel at the end over the bunk area. I need to replace the U-channel rubber gasket that I found is leaking.
At the end, it has clear sealant in a glob to cover where the rubber gasket stops. Does anyone have any idea what it might be?
As I said it's clear but flexible enough to put your fingernail into it.

Thanks, Dave