I know it is associated with the fuel system, but I can't find this orange inspection port under the fuel filter anywhere in the Owners Manual or Service Manual :confused2: Is this an area that should be lubricated with something?
I think all CK30H and CK30s beginning with s/n H703-0001 use this arrangement for the engine oil fill port. The manual stop lever and stop solenoid occupied this cover plate on earlier CK30 models.
That mechanical stuff is the side of the injection pump (IP) and the control levers for the IP. The "throttle" pulls the outside lever froward via a spring to increase RPM. The inside lever has a flat "stop" that limits the forward (more fuel) travel of the IP rack pin (sticking out of the IP case) when the engine RPM is correct for the throttle spring force. This "oil fill plate" can be removed to provide a convenient place to inspect the IP if you suspect the IP rack or gears are jammed internally.
The word throttle is really a misnomer for Diesel engines but that's what everybody calls the power lever. A true throttle restricts the flow of air into a gasoline engine. Diesels (most of them) have no such restriction so each cylinder gets a "full breath" on every intake stroke; only the amount of injected fuel varies to meet power demands. Diesels run very lean except at the highest power level, which is one reason Diesels produce so little carbon monoxide. The lack of a throttle plate is also why Diesels use so little fuel at idle; they don't have to work to suck air past a throttle plate as do gas engines.