Water Intrusion in Basement Bays

Scotty B · 08-11-2023, 10:04 AM

We went through some significant rain and water on the road on our way to this campground in Sturgeon Falls, ON. The bay in front of the passenger side rear wheels had significant water intrusion. This is the bay that is hinged at the top. There was also a little in the bay behind the rear wheels that is split with the fresh water tank above and storage below. The water here is mainly on the upper portion where the fresh tank is located. This bay is hinged on the side.
This happened once before on one of our legs up the Oregon coast - again during a significant rain storm. That time, we had just had a water pump go on the washer while in cycle and I had to drain manually, I wrongly assumed it came from that process - it is not an easy one!
I am not sure if the water is coming through the door seals or the seals in the wheel bay - maybe both? There was a storage container next to the wheel bay side of the more forward bay and it had a lot of water on the lid. Couple that with where the water showed up in the rear bay and I am leaning that it came from the wheel bay seals. We have never had an issue with washing water intrusion when washing the coach.
Any thoughts or advice would be greatly appreciated.
We are blessed that we have only had two weather days like that in 12 months of travel.
Safe travels!

Ray,IN · 08-11-2023, 01:39 PM

Keeping in mind water always flows down; I think your assessment of water spray from the duals is the source.
I assume the wheel-wells are curved like nearly all other MH's. I would clean thoroughly and use spray cans of undercoat to paint the entire wheel-well. If there's no wheel-well, are the compartments flat on top? The solution is the same.
I have a compartment just behind the LF wheel that used to leak during a hard rain- while driving only. It took a bit of contortionism to clean off the top and spray with undercoating, but it stopped the water leak.

Scotty B · 08-11-2023, 03:23 PM

Thx Ray...sounds like a good fix. I googled a bit more and seems to be a semi-regular issue in coaches with similar fixes to what you recommend. Wheel wells are curved. Will be a challenge to get in there for sure!

deckape · 08-11-2023, 07:14 PM

Have the same problem on my Forza . Water in the rear bays after duals . Were bins are connected to bin box , there was a unsealed seam . Winnebago had used a sealant but did not seal it well . I used 1/4 head tex screws to bring metal lip together . used a water hose to check and it stopped leak . Then sprayed a coat or two of undercoating in whell well and inside bin . Have stopped leaks in both bins .

Gallal · 08-20-2023, 04:44 PM

Could be water on the slide topper when retracting. I have experienced this.

danhannah · 08-21-2023, 08:51 PM

I solved this permanently with the following method.

Wait till pitch black night time. Put strong work lights in the compartment and close the door. Have a charged caulking gun in your hand, as you can now very clearly see every pinhole leak point as a spot of light. Hit it with the caulk gun.

Use a urethane caulk, not a silicone product for best results.

Alternatively, you can crawl inside the compartment on a bright sunny day, and have someone shut the door on you. (trust) After a few minutes of eyes adjusting, you will see every leak.

Door seals, surprisingly, are not usually the problem. They seal up pretty well even if way out of adjustment.

What a pleasure having bone-dry compartments.

Best of luck.