52.0.1 Engine block
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52.0.1 Engine block
The engine block is finished in a lusterless olive drab.
Cast markings: In raised letters and numbers from left right along lower passenger side of block housing in the folowing order. Months and Day shown as MM-DD, the Willys block "part" number 638632, the Wilson Foundry and Machine Code, i.e "W-1", W-2", etcetera. Last are symbols of the elements used to alloy the block, usually NI, CR and N2
The serial number pad, located behind the oil filter is stamped with the engine serial number. The engines were stamped with the "MB" prefix when the blocks were machined by Wilson, and the sequential serial number when Willys assembled the engine. Wilson also date coded the bottom of the block in the left rear corner of the oil pan mating surface at the time of the completion of the machining process.
Willys MB engine serial numbers begin at MB-100001 in 1941 and run up to about MB-636XXX in 1945. Although frame and engine serial numbers did not match when the MB was assembled they are related by an arithmatic skew. While there are exceptions to the skew rate they are extremely rare over the course of production. Generally, an authentically restored MBs competing in factry class judging should have an engine with casting and machining dates from several weeks to about 5 days prior to the MBs DOD. Only the early slat grills will have blocks cast and machined months before use. Once MB production ramped up in early 1942 these date lag times were overcome.
This date matching rule of thumb will ensure the frame/engine serial number skew is followed provided the block serial number has not been tampered with.
