WWII CCKW 353 Fuel Truck Engine Block
The block from the CCKW 353 Fuel Truck's once-seized engine shortly after disassembly began early in 2023. (image via Mil-Spec Restorations)

Progress in September/October:

The big news for our CCKW 353 Fuel Truck this month is the arrival of our freshly-overhauled engine block from the machine shop which Mil-Spec Vehicle Restoration contracted for the work. It is hard to believe that the primary components from the long-seized, rusty engine which we handed them a year ago could return in nearly brand-new condition, but that is precisely what this team of mechanical magicians has achieved!

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The freshly-overhauled engine block for the CCKW fuel truck. The unit looks so pristine that it is hard to believe that this magnificent work of art emerged from the dilapidated, seized-up hunk of junk which arrived at the workshop with our fuel truck a couple of years ago. Note the set of brand new piston rings sitting on the work bench and resting on the block. These will be fitted to a new set of pistons in due course. (photo via Mil-Spec Restoration)


The many tasks which the machine shop had to perform in refurbishing the Fuel Truck's GMC 270 straight-six engine included pressure-testing its cylinder head and block. They media-blasted the engine's exterior to remove any surface corrosion and then rebored and honed the cylinders, removing roughly .030" of metal from the surface. (To compensate for the greater cylinder diameter, the new pistons will use a set of appropriately oversized rings.)

Furthermore, the workshop refaced each of the engine's primary mounting surfaces, while also replacing the valve guides along with the intake and exhaust seats (grinding, then honing them to the correct specifications). Moreover, they also evaluated and refurbished the connecting rods and crank shaft as well. Once the machine shop had completed these tasks and other essential details, Mil-Spec collected the components for reassembly.

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A closeup view of the engine block showing one of several new cam bearings which Mil-Spec installed following their receipt of the overhauled engine components. (photo via Mil-Spec Restoration)


Since receiving the fuel truck's refurbished engine components, Mil-Spec has begun putting the powerplant back together. They first washed the block, and blew out the oil passages to remove any lingering contaminants from the machining processes. They then installed the cam bearings and expansion plugs, while also attaching the cylinders to the connecting rods. Amongst additional engine-related details, Mil-Spec also received a brand new wiring harness to rig up the engine's electrical system once it is ready to go.

The New Wiring Harness For The Cckw's Engine. (photo Via Mil Spec Restoration)
The new wiring harness for the CCKW's GMC 270 engine. (photo Via Mil Spec Restoration)

Additional Details:

While the engine reassembly process was perhaps the biggest sign of visual progress with the Fuel Truck of late, Mil-Spec has also been hard at work on other aspects of the rebuild. This has included work on both the braking system and the chassis. With respect to the brakes, they detected a leak in the master cylinder, but fixed the problem with a new seal. They have since made some final adjustments to the system and bled the lines, so it is essentially ready to go now. As for the chassis, the team has been working on the shock absorbers, installing the righthand front unit, along with the left and right front linkages. They also installed both the left and right front axle drive flanges. We look forwards to the coming month when we hope to see the engine further along its path to running again!