Rebuild Overview:
The team at Mil-Spec Restoration has been hard at work on the restoration of the Museum’s GMC CCKW Fuel truck. Their efforts this month focused on the engine, transmission, radiator and chassis.
Engine & Transmission Details:
The engine is now fully rebuilt and has undergone testing to ensure its full operability. The restoration team noted a problem with the Bendix starter. The issue turned out to involve worn drive teeth on both the starter and the ring gear (on the flywheel). As a result, the team replaced both items. They also removed and replaced the carburetor mounting studs to allow the installation of a New Old Stock governor for regulating engine rpm. The next items on the list involved installing the transmission on the engine, and then mounting the entire assembly to the Fuel Truck’s chassis. Our Fuel Truck is very close to being able to drive under its own power now!
Radiator Fan Shroud:
Every liquid-cooled, internal combustion engine requires a radiator to regulate its temperature via the coolant which circulates in a loop between the two components. To increase airflow over the radiator (and thus improve cooling) most engines also have a large fan right behind the radiator, which kicks in when the extra cooling is necessary. The Fuel Truck is no different. To protect the fan from debris damage during driving operations in rough terrain, and to help guide the air more effectively through the radiator fins, the Fuel Truck features a sheet metal shroud around the fan. Unfortunately, our Fuel Truck's original shroud was too corroded to reuse, so Mil-Spec Restoration fabricated its replacement, as documented in the three images below.
Part way through fabrication of the radiator fan shroud. The sheet metal structure has been cut, folded and welded into shape. The central opening and the mounting holes have yet to go in. (photo via Mil-Spec Restoration)
The engine's cooling fan shroud, with its central opening and mounting holes in place is ready for trial-fitting. (photo via Mil-Spec Restoration)
Trial-fitting the newly-manufactured engine cooling fan shroud to the GMC 270's radiator. (photo via Mil-Spec Restoration)
Radiator:
Following the fabrication and painting of the radiator fan shroud, it was time to attach the radiator (with its fan shroud) to the chassis. The appropriate hoses were also connected between the radiator and the engine block, with the system then being topped up with liquid coolant. The radiator itself is held within a purpose-built frame, with two hefty steel struts securing it rigidly against the chassis, as the images below attest.
Air Ducts:
The restoration team needed to refabricate an upper and lower air duct for the Fuel Truck, as the originals were too damaged to reuse. The manufacture of these parts was relatively straightforward, as they are constructed from sheet steel without any complex curves involved. Once the team had cut appropriately shaped blanks from the correct gauge of steel, it was simply a matter of using a sheet metal brake to engineer the correct folds in the metal. After sand blasting and painting, these parts were then ready to install.
This image displays an original air duct (top) with its replacement under manufacture in the foreground. At this point the replacement part has been cut from sheet stock, and is just awaiting the application of the appropriate folds to create its final form. (photo via Mil-Spec Restoration)
One of the air ducts following its fabrication and sand blasting. It now awaits final painting. (photo via Mil-Spec Restoration)
The upper and lower air ducts during fabrication, seen here hanging from hooks to dry following painting. (photo via Mil-Spec Restoration)