Engine Lubrication - GMC G Service Manual

6A6-2 6.2L DIESEL
6.2L diesels are 90 degree V8 engines with natural aspi­
ration and indirect type combustion chambers.
The crankshaft is supported by five precision insert main
bearings, with crankshaft thrust taken at the number three
(center) main bearing.
The camshaft is supported by five plain type bearings
and is chain driven. Motion from the camshaft is transmitted
to the overhead valves by roller type hydraulic lifters,
pushrods, and shaft mounted rocker arms. The valve
guides are integral in the cylinder head.
The connecting rods are forged steel, with precision
insert type crankpin bearings. The piston pins are retained
by snap rings.

ENGINE LUBRICATION

A lubrication schematic is shown in figure 1.
The gear type oil pump is driven from either the vacuum
pump shaft or from a drive gear, depending on engine
A. Forward
B. To Oil Cooler
C. From Oil Cooler
D. From Oil Pump
DESCRIPTION
application. The vacuum pump or drive gear is driven by the
camshaft. Oil is drawn into the pump through a pickup
screen and pipe.
radiator. A bypass valve is provided should the oil cooler
become restricted. Oil flows from the cooler to a full flow oil
filter. An oil filter bypass valve is provided should the oil
filter become restricted.
pressurized lubrication to various components.
leries. Oil flows from the hydraulic lifters through hollow
pushrods to the rocker arms. Oil from the overhead drains
back to the crankcase through oil drain holes.
rod small end bearing are lubricated by oil splash.
10. Rocker Arm
11. Camshaft Bearings
12. Oil Cooler Bypass Valve
13. Oil Filter Bypass Valve
14. Oil Filter
15. Cup Plug
16. Plug
17. Valve Lifters
18. Pushrod
Figure 1 — Lubrication Diagram
Pressurized oil is routed to the oil cooler, located in the
Oil flows from the oil filter to the oil galleries, providing
The hydraulic valve lifters receive oil from the oil gal­
The pistons, piston rings, cylinder walls, and connecting
F-08022