Chat up an engine dealer and ask for last year's DVD of an engine assembly.
I used to work for a Deere dealer who assembled generator units using their engines, for which we needed to know pretty much everything about the outside of the engine.
We got (and I don't have, sorry) almost complete 3D engine models, including all the components, without internals. I.e., the engine included a model of a cylindrical bar instead of a camshaft, and an obviously simplified crank, but included decent details of gears, pulleys, flywheels, engine accessories (with simplified internals), and a fully threaded model of every bolt, I think as STEP files. The split lockwashers drove me crazy, because SW always failed to interpret the split correctly.
Mike Halloran
Pembroke Pines, FL, USA