The rust issue - Undercoating and active system.

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
A

Artcele

Well-known member
Joined
Sep 13, 2015
Posts
46
Chassis rust is obviously a big issue for both owners and used RV buyers.

On the verge of buying my first used RV, this is a topic obviously high on my checklist as far as chassis inspection is concerned, and I am looking for solutions to keep the chassis without rust, or to early detect rust spot(s).

I found 2 products of interest, on the high/complex side:
- 3M? Body Schutz? Rubberized Coating
http://3mcollision.com/products/coatings/3m-body-schutz-rubberized-coating-black-8864.html
(Requiring a specialist to assess and prepare the chassis, before application)

And this less common Electronic Rust Suppression System:
- CATIII-4XHD - Extra Heavy Duty 4 Pad Rust Suppression System.
https://www.catsystemsaustralia.com.au/product/5353/

What about rust inhibitor sprays? Seems to me difficult, costly and not lasting enough, with such a huge chassis estate...

BTW, as a buyer of used RV, my fear is about rust encapsulator products, that I won't be able to detect, while inspecting a chassis.
"Your chassis looks very clean!" Sort of... Unvisible rust, well coated.

Experiences? Simpler ways but efficient?

 
Unless one has been used extensively ocean side, on the beach, I don't expect you will see the rust problems experienced with winter road salt. Not too many folks travel daily through winter conditions to get that level of exposure.
Having lived in the northeast, I would never undercoat a used vehicle (encapsulating) or even a new one. It will never be sealed and the rust will continue under the product.
If you're concerned with surface rust, spray it with phosphoric acid, then paint it.
Frankly, unless a particular vehicle is showing enough chassis rust as in pieces flaking off, I wouldn't be concerned at all.
 
^^ What Bob said ^^

There was one situation where a brand new 2004 Vectra was delivered in the winter to a dealer in the south (think the dealer was Lazydays) and the frame was a rusty mess. The receiving dealer did not pressure wash the chassis* and road salts badly rusted everything exposed. The customer pursued legal action against Freightliner, Winnebago, and the dealer; there was a settlement, and the dealer (or Winnebago) took the unit back. I have no other details about the settlement because the usual stipulation is you don't discuss the details.

I have first hand knowledge of the situation because the customer/owner called me to discuss the situation and get my opinion. When I looked at the pictures, I felt really sorry for the guy - there would be no way I would accept a rusty mess either.

As Bob pointed out, the usual surface rust is expected and is not an issue, however there can be a unique situation like my example above.

*Dealers are required to perform a pre-delivery inspection when they receive a unit from the factory

And lastly, undercoating was a factory option on our Horizon which I chose. It's not a very thick coating and I do believe it's helped the exposed sheet steel in particular stay mostly rust free. I would not ever do an after-market "undercoating", like Bob mentioned - that is asking for trouble.
 
I'm 100% in tune with Bob's reply. For sure, take a look underneath to identify the relatively few that will have notable rust issues, but don't get all twisted up about the subject. And I don't agree at all that rust should be "obviously high on my checklist".  It's just one of many things to be aware of and noted if present to some significant degree.

You can use phosphoric acid (Ospho or similar) to stabilize surface rust before re-painting. Once a rig has been on the road and in the weather, that's a far more effective treatment than any of those protective products. In my opinion, of course...
 
As a newbie, but not (yet) totally dumb, I have absolutely no idea of what I can expect underneath a chassis, and my way of saying could be read as a pessimistic one, what I am not at all !  :)
I understand that a thin and superficial rust look is no problem, I just fear, somehow, hidden rust undercover on a 10 years unit.

Chris made an amazing repair by changing a side panel around a compartment, and finding him being a great caretaker of his 36RD, and DIYer, I concluded that "it can happen" to any unit, to anybody.

John, I understand your nogo about undercoating used units, but these UK guys are first removing any critical spot, if any, before spraying the Schutz.
https://www.lasmotorhomes.com/rv-protection/undersealing-motorhome

36RD are not easy to find, calling for a long drive, so in front of a nice (upper/house) unit, I wonder how to deal with a little less satisfactory chassis. In doubt , my plan is to hire a mobile RV mechanic, or a pre purchase inspection, should I meet a nice 36RD, to get a chassis green light.

Gary, I downgrade the rust priority  :)  thanks you all for your inputs.

 
I've also heard of coaches that had electrolysis corrosion issues, either from dissimilar metals in contact, or electrical leakage.  I don't mean to poo-poo this sort of problem at all, but do feel it is not a glaring and common concern. Best I can say is, if you see evidence of significant corrosion, pause, start discussing it with the seller, and ask for further inspection on a lift by a qualified person.
 
Indeed, every time 2 different metals enter in contact, you get the very definition of a cell, where a current flows at this bi-metal junction, and perhaps on the outside loop.
Gary, you understand my approach: If less than a doubt arises, because I am not skilled enough, a specialist could assess instead of me.
Thanks to all of your real-life experiences and advices, I really refine my "feet on earth" knowledge before assessing my first RV.

By the way, when you visit a RV dealer finding an interesting unit, is it easy to test drive it? And to get authorized to inspect it in details, probably for hours?




 
when you visit a RV dealer finding an interesting unit, is it easy to test drive it? And to get authorized to inspect it in details, probably for hours?
Click to expand...

That depends entirely on the dealer and whether he believes you are a serious buyer or not. Some may ask for a deposit on a sale contract before letting you take the rig away for an outside inspection, but you can insist that it be refundable if you deem the inspection results unsatisfactory. In my opinion, if they aren't willing to do that, you probably don't want to do business with them anyway.
 
I looked at a Tour that just came in on trade, and when I got underneath and in the cabinets, I noticed all the cabinet framework was rusting.  If you pull back on the seals, they brought the paint with it and it exposed rust.  I assume this was from salt air or salt on the roads, but it was a reasonably big concern for me and that combined with some other hard use signs we saw we walked away.  It just seemed to be too much for a 3 year old unit.
 
Thank you to mention this, it seems rather easy to check, when assessing an unit.
Checking all cabinet seals added to my checklist.

I found 2 similar rust cases, concerning the windshield using a T-shape rubber seal, attached to the steel frame with just an adhesive.
https://community.fmca.com/topic/3592-leaking-windshields-on-winnebago-vectra

Itasca windscreen issue:
https://www.youtube.com/watch?v=zbXoyP9d5lI
The product they use:
http://www.dowautomotive.com/solutions/automotive-aftermarket/north-america/products/betaprime-5504g.htm

Checking possible leaks around the windshield is probably more difficult. Inspecting the windshield seal all around, from inside?

Gary, rust is climbing again (a little) on my inspection scale  :)
 
There have been some issues with rust on the metal frame the windshield is attached to, happened to me. It's fairly easy to spot, there might be rust tracks/strains somewhere on the dash. Second telltale sign is the rubber molding around the windshield glass will be lifted up because the adhesive on the molding won't adhere to the rusty frame surface. If the trim appears lifted up, a ladder and a visual inspection under the rubber will quickly determine the situation.

While the windshield frame rust is fairly easy to spot, the fix is more difficult. Obviously the glass needs to be removed and usually they break so you get to buy a new one in addition to the rust mitigation.
 
John,
After buying it, the unit goes to a local Winnebago (and Freightliner if needed) to get it clean and fully inspected/maintained.
If some rust has been detected on the windshield frame, they'll fix that, replacing adhesive, seal, sealant, etc...
Moreover, after buying an used RV, it is now obvious to me, that all seals, and adhesives when possible, have to be replaced.


Btw, I just read the Vectra care & maintenance section (14), underbody and sealants paragraphs.

Flushing the underbody every 3 months, or when needed, and checking ALL the sealants every 6 months, or less represent a serious and periodic task, and it is not surprising that units without these regular operations can reveal rust.

When you browse through the part catalog for Vectra, it is amazing to read the so many places where adhesives are listed.
Locations of these degradable components seems a good starting point to assess an used unit: (Roof/walls seal, windows, compartments, windshield, galley seal, bathroom...).
With a clean inspection of these, and a nice looking underbody, revealing only superficial thin rust (not crust), I would be motivated to follow with the house and truck/chassis inspection.






 
You must log in or register to reply here.

Latest posts

Members online

Total: 445 (members: 4, guests: 441)

Forum statistics

Threads
131,954
Posts
1,388,150
Members
137,708
Latest member
7mark7
Back
Top Bottom