TM 9-2910-226-34 1-20. Operation. The operation is described in relation to oil lubrication, fuel flow, fuel pumping and distribution, fuel metering and control speed governing, fuel density compensating, and timing advancement. 1-21. Oil Lubrication. NOTE The key letters shown in parentheses refer to figure 1-23 except where otherwise indicated. a. Oil enters under pressure from the engine at the pipe-to-tube tee (fig. 1-1) and flows to the timing device housing and through the oil hose assembly to the injection pump housing bushing type bearings (L). The remaining internal parts of the advance unit assembly are splash lubricated by oil in the advance unit housing oil sump (K). b. On code A, B, C, D, and E injection pumps, oil entering the injection pump housing flows up the main oil passage (D) to lubricate the tappet assembly (E). c. Code F and G injection pumps have an ad- ditional oil passage. Oil entering the injection pump housing flows up the main oil passage (D) to the oil filter (C). Filtered oil flows to the lower section of the fuel plunger (A) and to the gear thrust washer (B). Oil flows from the main passage (D) to lubricate the tappet assembly (E). d. A hole in the camshaft bushing type bearing (J) allows oil to flow from the main oil passage to lubricate the camshaft journal. A passage in the journal allows oil to flow through the camshaft oil passage (H). There are no oil passages in the friction drive spider. The weight pins are equipped with nylon type bearings which do not require lubrication. Oil flows through the camshaft oil port (F) to lubricate the sliding sleeve. e. The camshaft lobes, camshaft ball bearing, quill shaft drive gears and internal governor parts are splash lubricated by oil collected in the bottom of the injection pump. Oil drains back from the governor housing and pump housing through the timing device housing and returns to the engine crankcase. f. Code F injection pumps may have an additional oil drain (G) on the governor housing that returns oil through an external line to the oil pan. g. Early code G injection pumps have an oil passage (M) through the camshaft and friction drive spider to governor weight pins and bronze bushings. Later code G pumps have teflon bushings and do not require this lubrication. 1-25