Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
 
Old 04-28-2024, 09:35 PM   #1
Mini-Skoolie
 
Join Date: Apr 2024
Posts: 21
Rust Concerns - 2004 International 40' Pusher

Hey all, my wife and I bought our 40' International pusher from a local school auction recently. It's a 2004 with a DT466 and an Allison 3060, 180K miles. Overall an excellent setup for us to convert. We took the seats out and are starting on the floors. Near the front wheel well, noticing some pretty bad rust.

I used a hammer and pry bar to pound on this pretty hard, it did no puncture or seem super thin, but curious what everyone's thoughts are? Of course we'll continue stripping it and see what the whole story is.

Funny enough, the bus is super clean underneath, we live in western WA where there are rarely ever temps low enough to need road salts. But it's also wet in the winter, meaning water inside the bus can get trapped I suppose.

Are there treatments that can stop this in its tracks and allow us to not be concerned about subfloors? Should we add structure? This is our first conversion so I have no frame of reference for how bad it is.




aerowenn is offline   Reply With Quote
Old 04-29-2024, 09:22 AM   #2
Bus Crazy
 
ewo1's Avatar
 
Join Date: May 2015
Location: Central Tx.
Posts: 2,027
Year: 1999
Chassis: Amtran / International
Engine: DT466E HT 250HP - Md3060
Quote:
Originally Posted by aerowenn View Post

Are there treatments that can stop this in its tracks and allow us to not be concerned about subfloors? Should we add structure? This is our first conversion so I have no frame of reference for how bad it is.



Ospho!

Rust convertor works really well !

Brush it on, the inside/floor, and use a pump sprayer underneath the bus.

Wear PPE when spraying so it does not get into the face/ eyes!
ewo1 is offline   Reply With Quote
Old 04-29-2024, 11:44 AM   #3
Mini-Skoolie
 
Join Date: Apr 2024
Posts: 21
There's a POR-15 etching prep chemical I bought already that I think is the same thing as Ospho. It's meant to be used just prior to POR-15 coating application - I think they are likely the same thing (Phosphoric acid)?
aerowenn is offline   Reply With Quote
Old 04-29-2024, 06:50 PM   #4
Mini-Skoolie
 
Join Date: Apr 2024
Posts: 21
Any guidance on when to patch? So far we've not found any holes/punctures. It's heavy surface rust, flaking and whatnot, but still seems structurally sound. Kind of surprised at how thick some of the flakes are though.
aerowenn is offline   Reply With Quote
Old 04-30-2024, 06:15 PM   #5
Mini-Skoolie
 
Join Date: Apr 2024
Posts: 21
Just a follow-up to this thread for the question about "POR-15 Metal Prep".

It is indeed the same thing as Ospho (Phosphoric acid) according to the MSDS. Please don't confuse this with "POR-15" the top coat that is colored, the "POR-15 Metal Prep" is a product that POR-15 sells to prepare the surface for coating and does the same job as Ospho by converting rust.
aerowenn is offline   Reply With Quote
Old 04-30-2024, 06:20 PM   #6
Mini-Skoolie
 
Join Date: Apr 2024
Posts: 21
Phosphoric acid content:

Ospho 45% by weight
POR-15 Metal Prep 10-25% by weight

Not sure if people tend to dilute Ospho.
aerowenn is offline   Reply With Quote
Old 05-01-2024, 05:08 AM   #7
Bus Geek
 
musigenesis's Avatar
 
Join Date: Jan 2019
Location: Philadelphia
Posts: 7,011
Year: 2003
Coachwork: International
Chassis: CE 300
Engine: DT466e
Rated Cap: 65C-43A
Quote:
Originally Posted by aerowenn View Post
Any guidance on when to patch? So far we've not found any holes/punctures. It's heavy surface rust, flaking and whatnot, but still seems structurally sound. Kind of surprised at how thick some of the flakes are though.
Iron oxides (aka rust) are 6 to 7 times larger by volume than the iron/steel from which they derive. This is why the rust tends to flake off, because it's too large to fit within the matrix of the original metal (aluminum, by contrast, corrodes just as readily as steel, but aluminum oxides are roughly the same volume as pure aluminum so the corroded surface remains attached and protects the metal from further corrosion). So rusting steel can produce large flakes which do not actually comprise a large fraction of the original metal.

If you can't poke through the metal with a screwdriver, there's no need to patch it.

Quote:
Originally Posted by aerowenn View Post
Are there treatments that can stop this in its tracks and allow us to not be concerned about subfloors?
The key to stopping this rust in its tracks is to fix your leaks, which are most often from your windows and external light openings but sometimes your roof hatches and seams - water is the most essential ingredient for the corrosion process. You can treat your existing rust (with very little physical effort) by applying Ospho or similar product and then priming and painting with Rustoleum, and then get on with your subfloor construction.

Check out my build thread (link at the bottom of my post here) to see how I dealt with a severely-rusted bus floor. Your bus is not anywhere near that bad.
__________________
Rusty 87 build thread
musigenesis is offline   Reply With Quote
Old 05-05-2024, 02:57 AM   #8
Mini-Skoolie
 
Join Date: Apr 2024
Posts: 21
Thanks a ton for the info! Yeah after looking around, we're not bad off. No rust holes at all in the floor, very stable albeit with some pits. I did find a couple small holes around the wheel wells I will patch, but all in all I think we're fine. Ospho treatment starting tomorrow, then we'll be coating with POR-15.
aerowenn is offline   Reply With Quote
Old 05-05-2024, 05:31 AM   #9
Bus Geek
 
musigenesis's Avatar
 
Join Date: Jan 2019
Location: Philadelphia
Posts: 7,011
Year: 2003
Coachwork: International
Chassis: CE 300
Engine: DT466e
Rated Cap: 65C-43A
Quote:
Originally Posted by aerowenn View Post
Thanks a ton for the info! Yeah after looking around, we're not bad off. No rust holes at all in the floor, very stable albeit with some pits. I did find a couple small holes around the wheel wells I will patch, but all in all I think we're fine. Ospho treatment starting tomorrow, then we'll be coating with POR-15.
Having tried it (along with many other methods), I would avoid POR-15. It's expensive, extremely nasty to work with (if you get it on your skin it will take literally weeks to come off), doesn't adhere well to any surface with Ospho residue on it, and is completely unnecessary if you've stopped all your leaks.

Early on in my skoolie project, I took a bunch of rusty angle brackets that fell off the bottom of my bus and used them for rust treatment experiments. POR-15 works best when painted directly onto rusty steel (after removing any loose flakes) and in fact this is what the POR-15 instructions call for. When applied to steel that has been fully treated with Ospho but that still has a bit of the powdery residue on it, POR-15 forms a rubbery layer that peels off like a post-it note.

Priming and painting with Rustoleum works perfectly well and is much cheaper and less nasty to work with. You can even do this on rusty metal that has not been treated with Ospho beforehand and it works fine. I only used Ospho on my floor first because I feel a personal hatred of rust and I wanted to watch it all die in front of my eyes.
__________________
Rusty 87 build thread
musigenesis is offline   Reply With Quote
Old 05-05-2024, 07:04 AM   #10
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 18,920
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
ive used POR-15 when ive done car restomods.. it was most definitely the nastiest Paint ive ever worked with.. BUT it works.. I bought myself paper "suits" to work inand wore gloves every bit of the way.. I also had cheap tools that after each full project was done I tossed out.. ( not daily but ttypically I did all my POR-15 work at the same time during my build).. I had great luck with it lasting.. I typically was pretty quick about my prep work.. I would wire brush and then air hose the lose rust flakes away.. I never used POR-15's cleaner, i had always used dawn liquid with water and a power washer.. let it dry then used the POR-15 pre coat. and hen brushed on the POR-15 paint.. I had tried rolling it but it typically wanted to tear apart the rollers.. esp on the 2nd coat where you dont let the first coat totally dry..


I think of Ospho more as an acidic rust converter.. whereas POR-15 is a rust encapsulation system. you seal the metal so new rust cant form.. im not sure if you can POR-15 over ospho or not.. rustoleum oil based is paint.. if you paint it over rust, the rust will just come back through..



if you have metal thats rusting from the unseen side, you can ospho and paint and POR-15 all you want on the front but its not gonna slow the process down.. its gonna keep coming through.. in those cases you need to replace the metal.. thats often seen on body panels of busses.. esp the rear lower panels where water tends to get between the wall layers or the skirting where water is allowed behind and front..
cadillackid is offline   Reply With Quote
Old 05-05-2024, 11:36 PM   #11
Mini-Skoolie
 
Join Date: Apr 2024
Posts: 21
I too have a hatred for rust and want it to die; sad thing is, I'd already purchased POR-15 (1 gallon) and not sure it's returnable. Looks like there are better systems out there. You mentioned as long as the leaks are stopped, nothing to worry about. Is this because of the steel being galvanized in the flooring?

We have the floor cleaned now and it's drying, but at a crossroads on using our $300 in POR-15 or using something "better". I only want to do this once.
aerowenn is offline   Reply With Quote
Old 05-06-2024, 04:55 AM   #12
Bus Geek
 
musigenesis's Avatar
 
Join Date: Jan 2019
Location: Philadelphia
Posts: 7,011
Year: 2003
Coachwork: International
Chassis: CE 300
Engine: DT466e
Rated Cap: 65C-43A
Quote:
Originally Posted by aerowenn View Post
You mentioned as long as the leaks are stopped, nothing to worry about. Is this because of the steel being galvanized in the flooring?
Well, your steel floor was galvanized, but that protective coating is gone now - hence the rust. If your leaks are stopped, the floor won't continue rusting because steel corrosion doesn't happen without water, at least not to a significant degree. It's true that humidity in the air can cause corrosion, but it's an incredibly slow process (like, it would take many decades to eat through 16 ga sheet metal) and a subfloor would prevent air from coming in contact with the floor anyway. It's still worth treating and painting your floor just to be sure.

Quote:
Originally Posted by aerowenn View Post
We have the floor cleaned now and it's drying, but at a crossroads on using our $300 in POR-15 or using something "better". I only want to do this once.
If you've already bought the POR-15 and can't return it, use it and feel confident that you have the best protection possible, because that's what that stuff is. I only recommend against it because it's nasty, expensive, and overkill for this purpose.
__________________
Rusty 87 build thread
musigenesis is offline   Reply With Quote
Old 05-06-2024, 08:07 AM   #13
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 18,920
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
Quote:
Originally Posted by musigenesis View Post
Well, your steel floor was galvanized, but that protective coating is gone now - hence the rust. If your leaks are stopped, the floor won't continue rusting because steel corrosion doesn't happen without water, at least not to a significant degree. It's true that humidity in the air can cause corrosion, but it's an incredibly slow process (like, it would take many decades to eat through 16 ga sheet metal) and a subfloor would prevent air from coming in contact with the floor anyway. It's still worth treating and painting your floor just to be sure.



If you've already bought the POR-15 and can't return it, use it and feel confident that you have the best protection possible, because that's what that stuff is. I only recommend against it because it's nasty, expensive, and overkill for this purpose.



where i have always used it was on the underside of cars... the frame typically where the original p[aint has started to come off.. places that often come into contact with water from either driving or washing... but if i already had it i wouldnt hesitate t ouse it on the inside of the floor.. im not sure there is a such thing as a school bus that is 100% sealed from every leak.. driving 65 MPH through ab linding rainstorm puts a whole lot of extra air pressures on the bus that you cant test for in the driveway.. i suppose you could gut your bus, seal it up and wait for a blinding rainstorm to go drive in before you begin the interior conversion.. but I think some water should be planned for...
cadillackid is offline   Reply With Quote
Old 05-14-2024, 01:36 AM   #14
Mini-Skoolie
 
Join Date: Apr 2024
Posts: 21
Hey all, update here: We went ahead with POR-15 prep and finishing. Used 1 gallon and did 2 good coats. First coat it soaked up nicely and was tacky in 4 hours, second coat went on well. It's kind of shiny in some places and dull in others. I assume due to how much it absorbed (or didn't) in a given spot. Any concerns here enough to warrant another coat? I'm sure we'd have to scuff it up to do so. No metal showing that we can see.
aerowenn is offline   Reply With Quote
Old 05-14-2024, 08:27 PM   #15
Bus Nut
 
nikitis's Avatar
 
Join Date: Jun 2023
Location: South Carolina
Posts: 966
Year: 1995
Coachwork: Thomas
Chassis: International 3800
Engine: T444E
Rated Cap: 29
So my 2 cents.

I took a 1970 Dexter trailer which used to house a mobile home. It was a complete rust bucket. Had rusted all the way through in some places. I used a grinding wheel on the whole thing, patched the holes where it was too thin. Sprayed regular primer (not even automotive self etching, just regular gray primer), and patriot blue rust-o-leum paint. It's been 3 years now since I restored that trailer, and I see pretty much no rust returning. maybe like 0.01%. I've carried max weight on it which is 7k lbs. My Mini-Excavator (Yanmar 2004 pre emissions)

Rust once starts does continue. It doesn't stop, but you can slow it down or grind it away completely, and seal it. If you can get 100% of it, you can seal it and make it last forever. If you get most of the thick and loose stuff but miss some, it will still give it years longer than it would of had if you did nothing.

If you just grind away the lose stuff and leave a rusted surface it will still add a decade or two potentially to it's lifespan, but eventually you are cutting it out and replacing it.
nikitis is online now   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 07:29 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.