Rotting Roof Rust Remedies?

[Simy]

Sorry I haven't posted in awhile if your waiting on my microchip conversion I'm still waiting for parts, I will still update that thread when the time comes.

As far as now though, I've got a slight problem and I'm just not sure on the way to resolve it. I have been going with a top-down, outside-in approach to this conversion I figure once the roof and ceiling are done I'll start the walls, then the floors then do wiring, insulation, etc. The problem is I don't know what the heck I'm doing so please feel free to give me pointers where needed. I want to do everything right, and I would prefer to spend the time and money now while I can to ensure this bus lasts another 30-60 years, and lets face it -- that shouldn't be difficult.

The PO decided to lay down some tar, patch panels, bondo, tar, rubber roof, then more tar, and a top coat of rubber roof. I've been reading and apparently tar is bad, sure enough most sections of the roof have rust holes some large, some small. I've notices several panels that seem to be layered upon each other; 2 and 3 layers thick in some places.

My question is this. I need to stop the rust from spreading which means sanding and priming it correct? So should I remove the panels, patch the panels that are there by welding in new panels, or should I try to reseal the panels I have -- thereby leaving in some places 2-3 sheets of rusted metal in place. If I do the latter will the rust spread or will it stay put?

I don't mind doing more now to prevent myself from doing it later. While I'm not sure I'll be in the bus that long, I'm shooting for a 30+ year life span of this bus chassis. We plan to full time and I don't want to try to repair the roof, walls or windows on as large of a scale as we have been doing while trying to maintain a living area.

Thank you for your advise.

Some pictures:
http://imgur.com/a/ODBd6

[chessie4905]

what kind/make of bus is this?

[Simy]

Sorry its a 1986 Neoplan I believe the model is AN330/3, but I'm not 100% sure.

Pictures of the bus itself here:
http://imgur.com/a/NsCaz/embed

[luvrbus]

I love the look of the Neo, if it were me I would check everything out close before spending bucks to convert it they are prone to heavy rust from the top to the bottom nice buses though

[Simy]

Yeah, we bought it converted but the more we did and looked into the more we had to do and look into. I see why people give up mid conversion all the time. I'm just too stubborn and or crazy to quit

We knew there was some rust but were under the false impression that the roof was fine. It obviously isn't. Unless somebody says otherwise I think we are going to try to take off one of the panels and see what is under it when I get out of work today. I've got my vacation starting next week and I would like a solid waterproofed roof when my vacation is over.

[bevans6]

I restore and repair old British cars, if there is something I know about it's rust.  There is only one cure - cut it out and put in new.  The only rust that can be dealt with by sanding and priming is surface rust, and even that must be completely ground away or in some cases converted to a stable oxide with an acid bath, typically phosphoric acid (Naval Jelly is one example).  Now, I don't know about Neoplans, but the roof is highly structural on my bus and corrosion there would be critical to repair correctly.

Brian

[Simy]

My bus has a full frame and then a skin of metal on the outside held in by what I believe are rivets and some sort of soft grout between the beams and the sheet metal.

I do appreciate the reply, sounds to me like I'm going the correct direction, even if it means it will take awhile longer.

Thanks,
Tom

[grantgoold]

Por 15 (www.por15.com) is a great product that will convert rust to metal, or so the folks say. I have used it on the bus, old cars, outside metal furniture and never had any rust return. Love the stuff!

A bit pricey and make sure you never get any on your skin. Takes weeks to wear off!  A quart will cover quite a bit of space. The e-place is a good source or your local automotive paint supply.

I personally would replace the skin on the roof!

Grant

[bevans6]

POR 15 is a great product and I use it.  It's a two or three step process and step one is treat with what they call Metal Prep, which is dilute phosphoric acid (this is the actual brand the I do in fact use).  After the acid converts the rust the PO% 15 paint is applied with a brush, it brushes on (indeed wear gloves) flows out really well to a glossy finish and dries very hard, as it powder coat hard and you have to grind it off if you want it off for some reason.  Step three is a top coat if it will be subject to sun, as the colour fades quickly.  I use it on race car frames.

Brian

[chessie4905]

  Before you start on the roof, you need to check the underframe all over with an ice pick in suspect areas. You might find that there is a lot of hidden rot or frame cracks that would make continuing unfeasable. As far as the roof, I would completely strip it and remove all patches. Cut out any rusty areas, Prime with good rust preventative paint, and then recover complete top with new metal.

[Simy]

I appreciate the feedback. I get out of work in a bit over an hour. What I'll do is start from the back, check out that are first, and see what we have to do after the previous owners patches are removed. I think once we get a good idea of what is actually rusty and how bad I'll be able to make better informed decisions then. I'm just a bit worried about the process though.

As far as checking the beams from the inside I've sand blasted 80-90% of the roof beams, There are 2 beams that are a bit out of sorts but not too bad. Mostly just pitted, but plenty of material left. I have not seen any of them from the top down, I'm pretty sure I have some more prep to do from that angle.

When you say patch it and cover it with new material, are you saying put a second layer of metal on top of everything or just replace the material that is there? What benefit would that provide over just patching the holes by welding in new metal as needed?

Thanks again for all the feedback and advise!

[Jeremy]

I'm a bit surprised that a bus roof can rust as badly as this, especially on a relatively young bus - how and where on the roof was the water collecting to cause the rust?

My bus is of a similar age and construction except that the roof skin is a single sheet of aluminum from front to back, stuck on to the steel frame with Sikaflex. The aluminium skin is bent over the roof sides and continues down the sides of the bus several inches until the edges of the skin are trapped underneath an aluminum extrusion which is riveted in place, and which is covered by a rubber moulding incorporating a rain gutter. The rivets under that rubber moulding are the only rivets anywhere on the roof, and they are on the vertical sides where water wouldn't sit even if it could get to them. I'm describing this just in case you decide that the only 'once-and-for-all' solution for your bus is to get rid of the steel panels and (probably leaking) rivets altogether and re-skin the whole roof with aluminuim.


Jeremy

[Simy]

Sorry it took so long for a reply.


The way the panels were layered and screwed down left many places for water to enter, but none for it to escape. It looks like every time it got wet, the tar would allow the water to accumulate on top of the metal panels, but then wouldn't let it escape again, once the rust took hold it went nuts.

I have since removed all the rust and learned to weld, and used said skill-in-progress to weld patch panels in place.

As you can see my welding is by no means... professional.

http://imgur.com/a/Fn2UZ#0

I do have a few pinholes in my welds, I'm still working on that, in the meantime we need to protect the metal.

I'll start a new thread to ask my next question though

Thanks guys for all the feedback here, its helped.