Attention Winnebago Class C Owners

W8DBH_Don · 05-05-2006, 07:48 AM

While doing maintenance on my 1999 Winnebago Minnie 31G in the fall of 2005, I noticed the aluminum skin, on the inside of the lower sidewall, immediately in front of the driver side rear wheels, was corroded through in several spots. After removing the aluminum sheet (a utility knife works well), I discovered deteriorated plywood from water intrusion. See below with the forward splash shield removed.

While investigating for the entry point of the water, I noticed an unsealed cavity at the top of the wheel opening, where the motorhome floor meets the side wall. Notice the exposed foam of the wall lamination.

Upon further investigation, I discovered the same unsealed cavity behind the driver rear wheel opening as well as in front and behind the passenger rear wheel opening. The existence of these cavities can be verified by reaching into the wheel well, directly up from where the beltline trim stops at the wheel opening. Be careful! The edges of the aluminum are exposed and are sharp. Visual examination will require crawling underneath the motorhome. On the passenger side, the aluminum in front of the wheel shows no signs of deterioration, but the aluminum behind the wheel has delaminated toward the rear approximately 36 inches.

I attended the Detroit RV Show in February and examined the Winnebago Class C motorhomes on display. I found the same unsealed cavities, but there were no Winnebago representatives to talk with. I sent the information presented here to Winnebago engineers in March, 2006 and received a response indicating they would check into the situation immediately. It would appear that this is a common issue and warrants examination by anyone who owns a Winnebago class C.

For my motorhome repair, I used a urethane foam filler (be sure to allow for the expansion) to seal the cavities and coated the plywood with GitRot.

Since the area was small, I simply covered the exposed plywood with overlapping strips of 4 inch wide Eternabond. For a larger area, I think adhering an appropriately sized piece of aluminum roof flashing and sealing the edges with Eternabond would work well.

Edit: repaired photo link so pictue would display

W8DBH_Don · 05-05-2006, 07:48 AM

While doing maintenance on my 1999 Winnebago Minnie 31G in the fall of 2005, I noticed the aluminum skin, on the inside of the lower sidewall, immediately in front of the driver side rear wheels, was corroded through in several spots. After removing the aluminum sheet (a utility knife works well), I discovered deteriorated plywood from water intrusion. See below with the forward splash shield removed.

While investigating for the entry point of the water, I noticed an unsealed cavity at the top of the wheel opening, where the motorhome floor meets the side wall. Notice the exposed foam of the wall lamination.

Upon further investigation, I discovered the same unsealed cavity behind the driver rear wheel opening as well as in front and behind the passenger rear wheel opening. The existence of these cavities can be verified by reaching into the wheel well, directly up from where the beltline trim stops at the wheel opening. Be careful! The edges of the aluminum are exposed and are sharp. Visual examination will require crawling underneath the motorhome. On the passenger side, the aluminum in front of the wheel shows no signs of deterioration, but the aluminum behind the wheel has delaminated toward the rear approximately 36 inches.

I attended the Detroit RV Show in February and examined the Winnebago Class C motorhomes on display. I found the same unsealed cavities, but there were no Winnebago representatives to talk with. I sent the information presented here to Winnebago engineers in March, 2006 and received a response indicating they would check into the situation immediately. It would appear that this is a common issue and warrants examination by anyone who owns a Winnebago class C.

For my motorhome repair, I used a urethane foam filler (be sure to allow for the expansion) to seal the cavities and coated the plywood with GitRot.

Since the area was small, I simply covered the exposed plywood with overlapping strips of 4 inch wide Eternabond. For a larger area, I think adhering an appropriately sized piece of aluminum roof flashing and sealing the edges with Eternabond would work well.

Edit: repaired photo link so pictue would display

Joe-K · 05-05-2006, 10:35 AM

W8DBH_Don,

First off, Welcome to iRV2 and a hearty

for providing such an informative post.

Identifying a possible area for other owners to inspect on their coaches most likely has saved someone a pretty penny in future repair expenses.

Hope to see more of you around the board.

**"007"** · 05-05-2006, 11:31 AM

Thanks Don for a great informative post and also welcome to irv2

"007"

Lorna · 05-05-2006, 06:01 PM

It may be a place where everyone who has a class C needs to look. So many are made the same way. We recently bought a 1977 Midas Class C. We are currently in the process of ripping out the wall paneling down to the styrofoam and 2X2 studs (and adding a little more support in a couple of places). We have found a fair amount of rot due to the aftermarket ladder and luggage rack on the roof. The factory also apparently screwed 2 of the cabinet screws through the roof causing a nice rotted out spot. I have also found tiny pin-holes in the aluminum underside of the cabover. This rotted out the plywood decking of the cabover bed from the bottom. Most of the top surface looked okay but a tiny corner was peeling up so I started picking at it and ended up cutting out a 2ft X 2ft section out of that corner and discovered the framing members in that corner were rotted completely away. I then started picking at the other corner and discovered underneath the seemingly solid plywood, it was damp "dirt". I guess the heat and moisture kinda "composted" the plywood. On the exterior the pinholes look like tiny bumps of corrosion and are very difficult to see. Oddly enough the front cabover window had the least damage of the area. A little water can sure cause a lot of damamge! But even if we put $1000 into the reno (repair ceiling and cover with anaglypta wallpaper, beadboard walls, parquet floor, new bed, deck & drawers under bed, new laminate countertop, recoat roof with KoolSeal and adding a small electric ref to crank up to the max to use as a freezer is coming out to way under $1K) we will be able to use the Class C for far longer than if we ignored the damage. Besides, the Onan Genset alone is worth what we paid for the whole camper! Now I'm trying to figure out what I could paint the whole exterior of the camper with that will seal any pinholes that I may have missed. When we KoolSeal the roof, I'm going to see how it looks on a vertical test piece of metal when applied with a foam roller.