Water in Cabover!

When I bought my 'C' new about 10 years ago, the folks at the dealer told me that they needed to seal around the marker lights before I could have it. They said that the manufacturers use power screwdrivers when installing them and it creates hairline cracks around the openings when they over tighten. It happens so often that they fix it before it happens on new units.

Explorer1016 wrote:
We used a high 7000 cfm blower door system designed for energy audits of residential and commercial buildings.

I looked those up and they look like this:


I'd like to have my own tester. Sealtech Manufacturing Company makes the $4000 one used by good RV shops. Yep. Four Grand. What can I build for less that'll pressurize an RV?

I've heard that some have been able to do a pressure test with their Fantastic Vent set on IN and High. Our 31-ft has two. FantasticVent shows its flow at 920 cfm. Harbor Fright has an 8" portable blower rated 1700 cfm. The webpage for that commercial door tester showed capacity a pinch below 7000 cfm but the test they showed in a video showed it was testing properly at 2200 cfm. RV is much smaller.

Maybe I'll go do a trial...

One more important note;
Do not use any type of household caulk or silicone. Even if it product states it stays flexible. It will become hard, then brittle then dry out from sun and heat and crack and then you have new leaks.

I have used acetone on several of my rubber roof membranes with great results. Have never caused damage but cleans very nice and removes old adhesive residue. That is my equipment, yours could be different. Test an area first then proceed.

Explorer1016 wrote:

Dawghouse92 wrote:
Thanks guys! I am going to check marker lights and seams tomorrow. The flooring doesnt have any soft spots and the walls feel fine except 1 spot of very corner. I assume thats where it sits until it made its way in.

If I reseal the seams do I need to get old caulk/sealant off or just seal over it?

You absolutely have to remove all of the old sealer and residue if it is to be done correctly. I have had good luck with acetone

is acetone harmful to tpo or epdm roofs? a heat gun may help get old stuff off. use dicor

Dawghouse92 wrote:
Thanks guys! I am going to check marker lights and seams tomorrow. The flooring doesnt have any soft spots and the walls feel fine except 1 spot of very corner. I assume thats where it sits until it made its way in.

If I reseal the seams do I need to get old caulk/sealant off or just seal over it?

You absolutely have to remove all of the old sealer and residue if it is to be done correctly. I have had good luck with acetone

Thanks guys! I am going to check marker lights and seams tomorrow. The flooring doesnt have any soft spots and the walls feel fine except 1 spot of very corner. I assume thats where it sits until it made its way in.

If I reseal the seams do I need to get old caulk/sealant off or just seal over it?

I just performed a pressure test yesterday. We used a high 7000 cfm blower door system designed for energy audits of residential and commercial buildings. So, I thought all of my marker lights were sealed because "they looked like they were". 3 on the rear were leaking and 1 in front. Also had bubbles coming from my left front seam at cab over. i have tried different ways to look for air/water seepage in my rig and the blower door was the only thing that truly worked. I am removing all of my original marker lights, cleaning the old sealant with acetone and installing all new LED lights. I am using no sag dicor for mine. After i fix the front seam and install all new lights we will test again. Leaks are very hard to find unless you use the right equipment.

Look at the roof where it joins the cab and also around the front molding
on the cab-over. Also check the top clearance lights at the gaskets and
all windows.

It is also a good time to look for any soft paneling and cab-over flooring.


Good luck. Hope it turn out to be minor.

Frequently it is the clearance lights that leak. Try resealing them