Lets say you have a steam locomotive with a metal cab (including the roof) that has been sitting outside for the past 60 years. The cab roof now not only leaks but has started to rust through in places. The rust through has not affected the structural integrity of the cab roof yet.

There is a desire to perform some cosmetic work on the locomotive (which will remain an outdoor, uncovered display) and the cab roof needs to be sealed to stop the leaks and prevent further damage. While I understand that the correct repair is to replace the rusted through portion of the roof, this is not in the cards now or anytime soon.

Does anyone out there have any suggestions for a solution? A semi long term, low cost fix would be ideal, but I am open to any ideas.

Locomotive is AT&SF 811 in Atchison Kansas.

Jason Midyette

Jason -

The cab of our C&O Kanawha (#2789) was rebuilt a few years ago by an outside contractor but I have recently noticed the same problem that you mention with the roof of the 2-8-4. I guess I hadn't realized that the roof had not been rebuilt.


Les Beckman (Hoosier Valley Railroad Museum/North Judson, Indiana)

EDPM rubber... I know RMNE has been using it on their coaches to good effect.

Hi Jason - might try Henry elastomeric roof coating with patching tape bedded into the goop along the rotted seams. It can be painted over to match the rest of the roof once completely cured. I bed the tape into the sealant, then apply 3-4- cover coats as necessary. Good luck.

dave

Regrettably there isn’t a quick fix that will last for any length of time. There is severe corrosion at the lap joint and although you can cover it with all manner of miracle stuff the corrosion with continue to grow. You want to remove the center panel remove the rust and apply a new panel. Also after cleaning the sheet metal, apply a rust conversion coating which chemically alters the iron oxide and serves as a prime for the final finish. There are many out there. Rustoleum make a good one. Elastomeric roof coverings are great. With a small area such as this you could find a remnant from a roofing job usually for free. Be sure to glue the entire surface and not just the edges as is typical in construction. Henry’s is a good product also.

That said, arrest the decay first or you will be wasting time and effort.

CCdW

Use a torch to heat the areas that have the pack rust, then using either a sledge or preferably a rivet buster with a flat snap, beat the rust out of the seam. Then you can get in there with some sort of rust converter, paint or whatever you choose to coat the seam. Then you can apply the rubberized roofing.

https://youtu.be/k3qC-pXYqqw

Here's an approach I used for a similar rust-through situation.

In 1987, I patched some rust-outs in a signal case using a fiberglass patch kit.

I first thoroughly prepped the remaining metal with a wire wheel to remove rust and clean the metal as best as possible. I then applied rust converter to convert any remaining rust, making sure it penetrated behind the sheet metal. I then primed the metal, making sure to get paint in behind the metal as best as possible. After primer was all dry, I laid the fiberglass patches over the holes where the metal was missing. After the fiberglass cured, I sanded it smooth, then did a small amount of bondo bodywork followed by more sanding to make the patches invisible.

In this photo, the rust-out was somewhere along the bottom edge of the sheet metal where it is riveted to the cast iron base. I can't find the exact spot any more. The rust has not returned, and that was almost 30 years ago now. So that turned out to be a very good fix and did not involve any metal work or welding (neither of which I am trained to perform).

At the Museum of Transportation in St. Louis we had a similar situation. The cab of the Wabash 573 had major holes and much rust. We cut out the badly rusted metal and welded in new metal. We caulked all of the leaking rusty and delaminated seams with paintable acrylic caulk. Then we painted the entire cab top PPG PITT GUARD a 2 part epoxy. 97-147 is the gray A part and 97-149 is the B part. When it cured we painted it black. We also use this epoxy coating on the boiler after asbestos mitigation when we are going to install new lagging

Since welding in new metal is out of the question I have some suggestions. Caulk the leaks, fiberglass the leaks or cover the leaks with aluminum foil duct tape. Then paint the entire roof with PITT GUARD like we do.

Fiberglass is too rigid for large steel roofs exposed outdoors to temperature extremes, and the movement of a railroad vehicle rolling down the rails.

For example, Southern Pacific RR applied fiberglass to waterproof the steel air conditioning "bubbles" on the clerestory roof of S.P. 141 "Oakland" business car. Eventually the fiberglass cracked at some of the roof seams. GGRM replaced the fiberglass with a more flexible rubberized coating.

Small fiberglass patches should not have the cracking problem. Localized corrosion damage in steel ship hulls is routinely patched with Intergard "Red Hand" epoxy filler:
"A two package, polyamide cured, epoxy filler designed for use in gouges, dents and corrosion pits in steel. May also be used in fairing any irregularities which may occur in fabrication."
http://www.fisheriessupply.com/interlux-intergard-eaa200-eaa201-filler-red

- Doug Debs

I gotta go along with the warning about fiberglass - I've had to remove it from two passenger car roofs after it failed, but was still stuck down between the cracks. That was not fun.

dave

There is no magic goop. Any goop will last for a few years at most and then make the future repairman hate your guts. I have 22,000 square feet of roof that was repeatedly gooped in leaky spots, where it's in the way of any other repair. It is too much to remove, so now our only choice is to replace the roof.

Fiberglass might be an option due to being static. Fiberglass is two things at once: an epoxy coating and fiber structural reinforcement. Since it doesn't appear to need structural strength, the only meaningful part is the coating. The real problem is the rust will continue to bloom unabated underneath the coating. That will be the same for all coatings.

If you have discovered a magic coating which makes rust stop rusting, please tell me as it will end my search. However the last thing I need is more noobs bouncing up to me with a bottle of goop and a fish story from a salesman or a label. Most of those fish stories have a 3 year warranty, at which point they become a liability and impediment to further repair.

Nothing works -not rust converter, not wirebrush, not needle scaling- except media blast to near white metal (SSPC SP10) followed by any of a variety of quality primers. That is held out by NASA and others' very extensive research on the subject.

We have a gondola that lives in Michigan winters. It was media blasted to SP10 and painted with Standard Detroit Paint Co. (defunct)’s non-lead primer ($12/gal at the time) and their topcoat, in 1987. The topcoat lasted 20 years but the primer is still going strong and is slowly being overcoated with Awlgrip 545 2-pack epoxy primer and their G/H topcoat which is LPU. The areas painted in 2010 cannot be distinguished from the areas painted in 2014.

The gon also had new metalwork which had rusted. This was wirebrushed, "quality" rust converter, 545 and G/H topcoat in 2009. It failed by 2013.

There is no magic goop.

In your case it looks like the center sheet is taking the brunt of the rust. I would drill out the rivets, remove it, replace it with steel or a composite material. I would not throw EPDM over it since the roof is all steel and provides no convenient holes or mounts to affix the EPDM around the edges. I would certainly not glue any roofing material down to rusty steel unless your aim is to make rust for a future thermite project.

Another thing to consider is painting zinc paint "galvanizing in a can" on the steel. It won't seal but may entice the rust to attack the zinc instead of the steel.

LIKE!!!!!!


This is the only way in which time will be well spent. Also, I'd prep and rust convert the entire roof!

Just don't step over any knee high chains to get at the locomotive.

One small note, which may be obvious but I throw it out anyway:

I'd be sure to buck the 'inside' of the roof carefully before using the buffer-plate-and-snap method to loosen the rust and get out the buckles. I'd wonder if something like a screw roof jack with a suitable spreader plate at the bottom (to avoid any damage to the deck) might be adapted to work as an adjustable 'bucking dolly' there.

Yes, on such a thin section bucking the back side is essential. Otherwise you are just making noise.