Overview:
Several months have elapsed since the last update on our General Motors CCKW 353 Fuel Truck, which is undergoing a comprehensive rebuild at Mil-Spec Vehicle Restoration in Belvidere, New Jersey. The restoration team had just stripped down and sand-blasted the Fuel Truck's cab, then sprayed the bare-metal frame in a protective coat of red primer. The freshly-painted cab looked beautiful from a distance, but the paint's uniformity helped to reveal numerous corrosion issues which might otherwise have been hard to catalogue. With that information now in hand, Mil-Spec carefully moved through the structure to effect the necessary repairs.
Steel Corrosion Remedies:
Our Fuel Truck sat exposed to the elements for decades before the Museum rescued it from almost certain oblivion five years ago. With little effort expended by the previous owners to prevent moisture seeping into the vehicle's structure, water was effectively allowed to pool anywhere from which it couldn't escape. This permitted corrosion to dig deeply into some areas, particularly in the cab's sheet metal floor and lower parts of the doors. However, even the top surface of the roof showed signs of significant rust damage. Obviously, minor pitting is easily dealt with, so long as the corrosion is fully removed and treated. Remaining blemishes can then be smoothed over with filler and repainted to make the part appear as good as new.
Mitigating more serious corrosion issues in steel structures is relatively straightforward in most cases, so long as the correct materials and techniques are used. Small holes can simply be welded over with excess material filed down to the correct contour, while larger sections of corrosion can be cut out and replaced with new material welded in its place. The latter effort does require a modicum of skill to get right of course.
First, the new steel must be shaped to match the part's original profile. Then the replacement section is tack-welded in place temporarily to ensure it is properly aligned before welding along each seam. The tack welds serve a second purpose too, as they help prevent the sheet steel from warping during the final welding process (which obviously generates a lot of heat)! Where necessary, excess weld material along the bead is filed down to match the part's original profile, making the welded join almost impossible to discern after paint is applied.
A rectancular section of corroded sheet steel cut from the lower rear right corner of the truck's cab was cut away in preparation for welding in new metal. The circular hole, the result of a post-war modification to the Fuel Truck, is also slated for plating over here. (image via Mil-Spec Vehicle Restorations)
The section of corroded metal cut from the cab's frame. (image via Mil-Spec Vehicle Restorations)
The cab following the installation of new steel to repair the damage depicted in the previous images. Note the new section of steel tack-welded along the rear rim of the cab at center right, too. (image via Mil-Spec Vehicle Restorations)
A closeup showing the corrosion damage along one edge of the seat support. (image via Mil-Spec Vehicle Restorations)
The seat support after new material has been welded in to replace the corrosion-damaged material cut away from one edge. Note that the dent in the previous image has also been fettled out. (image via Mil-Spec Vehicle Restorations)
As an aside, it should be noted that this form of repair is not typically available to WWII-era aircraft constructed from aluminum alloys like 2024, since the welded seams can become fracture points (for a number of reasons) unlike with steel.
Cab Floor:
The low points in the cab floor had several areas of significant corrosion. The Mil-Spec team cut out the damaged portions and welded in replacement material of the same thickness and alloy as the original. The images below trace some of this journey, with the final shot revealing the magnificent end results!
A freshly-welded section of new steel (center of the image) shortly after the bead has been applied. The crocodile clip clamped at the upper right is the grounding lead used in the arc welding process. (image via Mil-Spec Vehicle Restorations)
An area of the cab floor (image center) which has been completely corroded through. Note how someone has scored lines into the paint around the damage; these mark out the dimensions of the material which will be cut from the frame and replaced. (image via Mil-Spec Vehicle Restorations)
A image captured after the damaged material shown in the previous image has been cut out and replaced. The welded bead around the new material has also been ground smooth, with body filler applied in places to smooth over any pitting in adjacent material. (image via Mil-Spec Vehicle Restorations)
Cab Roof
As already intimated, the cab's roof exhibited areas of significant pitting in the top surface. When original paint flaked away, moisture gathered around the cracked edges - the subsequent corrosion slowly eating into the steel, thinning it away entirely in places. To remedy the situation, the Mil-Spec team cut away the worst of the corrosion, replacing rusted metal with fresh steel in two adjacent, rectangular patches. Before welding in the new material, the team first tack-welded a pair of sturdy steel strips conforming to the underside of the roof near the openings. This helped stiffen the structure and prevent it from warping under the intense heat which the arc welding process generates.
Numerous small holes in the roof, some resulting from corrosion and others from post-war modifications, were welded over and sealed. Any welded seams standing proud of the roof's surface were then ground down and sanded to preserve its original profile. The team also fettled out a few dents, smoothing over any remaining blemishes with body filler. With these repairs complete, the roof received a coat of new paint so it appeared almost brand new.
An interior view of the cab's roof (the windscreen opening is to the right). Of note are the large rectangles of new material which have been welded in and numerous patched holes. Note also the two conformal stiffener strips affixed to the under surface of the roof to prevent it from warping during the arc welding process. (image via Mil-Spec Vehicle Restorations)
An interior roof support channel for the cab, seen here after repairs which involved splicing in a section of new material. (image via Mil-Spec Vehicle Restorations)
Doors
The restoration of each door began by disassembling it into its component parts. This involved first removing the interior panel, the door latch, linkage, handle and hinges, along with the window glass, cover, seals, and frame.
As it happens, the righthand door was too badly damaged to reuse in its entirety, but thankfully a New Old Stock (NOS) replacement was available, albeit slightly shop-worn. This was cleaned up, repaired and repainted for reassembly. The lefthand door was media-blasted to remove old paint, dirt and corrosion, although the lower extremities required significant 'surgery' which saw about six inches cut away and replaced with new metal. Areas with mild pitting were smoothed over with body filler and repainted, while a half dozen extraneous holes in the exterior skin needed welding over and filing down. New hinges were also sourced and installed in each door.
The left door interior skin right beside the window had several non-standard holes drilled in it. Four of them are visible here following welded repairs. (image via Mil-Spec Vehicle Restorations)
Some of the rusted material cut away from the left door. (image via Mil-Spec Vehicle Restorations)
An interior view of the new material on the lower edge of the left door. (image via Mil-Spec Vehicle Restorations)
Another view of the repairs to the lower edge of the left door. This is a view from the interior side. (image via Mil-Spec Vehicle Restorations)
The left door following the repairs to the lower edge (note the shiny new material). The grey and blue splotches on the panel show where filler was used to patch any rough surfaces resulting from minor corrosion pitting. Two new hinges have also been installed. (image via Mil-Spec Vehicle Restorations)
The refurbished, partially reassembled left door during trial-fitting. (image via Mil-Spec Vehicle Restorations)
The fully restored inner panels for the doors, the lefthand example being on the left. Both of these parts required media-blasting to remove surface corrosion, plus a little filling to repair surface pitting. (image via Mil-Spec Vehicle Restorations)
Some of the refurbished door parts. Note the two latch assemblies and door handle towards the lower left. (image via Mil-Spec Vehicle Restorations)
The NOS righthand door after repainting, sitting alongside the freshly-restored original interior panel, ready for reassembly. (image via Mil-Spec Vehicle Restorations)
The partially reassembled right door during trial-fitting against the cab following refurbishment. Note the new hinges. (image via Mil-Spec Vehicle Restorations)
Hood, Fenders & Panels
The hood was relatively intact, although it did require some holes filling in and new metal along the forward lip. The side panels were in decent shape, and merely needed media-blasting and repainting. The same proved true for the fenders.
The left forward corner of the Fuel Truck's hood showing that several superfluous holes have been welded over. (image via Mil-Spec Vehicle Restorations)
The excess weld material has been ground away from the hood edge. (image via Mil-Spec Vehicle Restorations)
Replacement metal has been welded on to the forward lip of the Fuel Trunk's hood. Excess weld material will be ground away from the seams, afterwhich the structure can be repainted. (image via Mil-Spec Vehicle Restorations)
Preview:
With most of the structural repairs to the cab now complete, next month should see the reassembly process begin at some point. The image below shows the cab following the respray of the repairs in green paint. It has been a remarkable transformation from the disheveled, rust-eaten carcass it once was!
