My biggest nightmare has come true?..Rust!

[Scoundrel]

Chalk it up to a lack of experience, I purchased my RV without going under it to check the belly.
Now that I finished re-coating the roof I decided to go under to see how things look and to fix a loose generator exhaust pipe clamp. Holy cow there is rust everywhere! The guy I bought the RV from told me it was a California RV and hadn?t spent any time on salt laden roads but after looking at the rot underneath and seeing the white residue I could tell he wasn?t being completely honest.

My questions is, is there something I can spray on that will stop the rust from propagating and causing more damage? If so should I apply rubberized undercoat afterwords to protect it from further exposure?? ? ? ? ? ?

 

[caltex]

I would use a wire brush and paint on a rust converter.

 

[Kirk]

A bit more information would be helpful. What is the RV? Year & make? Trailer or motorhome?  Class A, B or C?

I would guess from your post that you have a motorhome. Most all motor vehicles will have a rusty look to the under carriage, so I would gather that it is much more than that. If so, cold it be that the RV spent a lot of time at the beach? Salt air will cause rust to be much more rapid than other locations. But knowing the cause is only a part of the answer. First you need to do something to remove excess rust and to inhibit more. I would start with a good pressure wash followed by a a steam cleaning. After that a good quality undercoating job should go a long way to solve the problems.

 

[Scoundrel]

A bit more information would be helpful. What is the RV? Year & make? Trailer or motorhome?? Class A, B or C?

I would guess from your post that you have a motorhome. Most all motor vehicles will have a rusty look to the under carriage, so I would gather that it is much more than that. If so, cold it be that the RV spent a lot of time at the beach? Salt air will cause rust to be much more rapid than other locations. But knowing the cause is only a part of the answer. First you need to do something to remove excess rust and to inhibit more. I would start with a good pressure wash followed by a a steam cleaning. After that a good quality undercoating job should go a long way to solve the problems.

I own a 1992 Fleetwood Flair Class A.
I doubt seriously that a steam cleaning will remove rust. It has been my understanding that rust has to be removed not just covered up. Rust migrates like a cancer and id not stopped will continue to corrode. I was hopping there was a spray that would neutralize the rust thus allowing me to spray on a good thick coat of undercoating....
 

 

[Tom]

I was hopping there was a spray that would neutralize the rust thus allowing me to spray on a good thick coat of undercoating....

There is. It's the "rust converter" that Caltex mentioned. I've only seen it in a spray can, but I guess you can also buy a paint-on version. It goes on like a paint and "converts" the rust to a primer. I'm not at home right now or I'd go out to my garage and get the brand name.

 

[Scoundrel]

Thanks, I'll search the net and see what I come up with.....

 

[caltex]

There are a lot of brands of rust converters, they come in spray cans and in gallon buckets (which is what you will probably need) to be put on with a brush.  It isn't necessary to get all the rust off, if it's not flaking just paint on the converter.  You will end up with a hard epoxy like coating which could be painted if you want but is durable without painting. Just put "rust converter" in Goggle and you will have as many brands as you want to look at.

 

[Gary RV_Wizard]

As Robert (caltex) says, you only need to remove the loose, flaking stuff before using a "rust converter". They work reasonable well - I have used it on rusty tools and such, though never anything as large as a chassis.

As pressure wash or steam clean will get much of the loose stuff off and gets into a lot of nooks and crannys better than you can with a brush. Also gets rid of pockets of dirt & caked mud/grease so the converter and be applied there.

Rusting stops if the air is sealed out, so to some extent covering rust will work as long as there is no oxygen in the covering itself. Notice that metal that is far under water doesn't rust much, but nearer the surface where air mixes readily with the water it will corrode badly. A paint, such as Rustoleum actually helps quite a bit to prevent further rust. So do anti-rust primers, but the "rust converter" products do better.

 

[Scoundrel]

I purchased a pint can to start with. It turns the metal surfaces (and any other for that matter) black and leaves a hard film surface. The can says you can paint directly over it once it has cured but I found that paint fish eyes unless you prep the surface just as you would a non primed surface.

When the instructions say "Don't get it on any surface other then where the rust is" they mean it! Even a drop on a driveway will turn the concrete black and it won't come off...

I think I'll spend the next few days crawling underneath my RV and applying this stuff everywhere..... :'(

Then I'll apply a heavy layer of undercoat....that should do it..