Jeep 1996 Grand Cherokee Service Manual - page 991
Engine lubrication system consists of a rotor type
oil pump and a full flow oil filter.
The cylinders are numbered from front to rear; 1,
3, 5, 7 on the left bank and 2, 4, 6, 8 on the right
bank. The firing order is 1-8-4-3-6-5-7- 2 (Fig. 2).
The engine serial number is stamped into a
machined pad located on the left, front corner of the
cylinder block. When component part replacement is
necessary, use the engine type and serial number for
reference (Fig. 3).
LUBRICATION SYSTEM
A
gear—type
positive
displacement
pump
is
mounted at the underside of the rear main bearing
cap. The pump draws oil through the screen and
inlet tube from the sump at the rear of the oil pan.
The oil is driven between the drive and idler gears
and pump body, then forced through the outlet to the
block. An oil gallery in the block channels the oil to
the inlet side of the full flow oil filter. After passing
through the filter element, the oil passes from the
center outlet of the filter through an oil gallery that
channels the oil up to the main gallery which
extends the entire length on the right side of the
block. The oil then goes down to the No. 1 main bear-
ing, back up to the left side of the block and into the
oil gallery on the left side of the engine.
Galleries extend downward from the main oil gal-
lery to the upper shell of each main bearing. The
crankshaft is drilled internally to pass oil from the
main bearing journals to the connecting rod journals.
Each connecting rod bearing has half a hole in it, oil
passes through the hole when the rods rotate and the
hole lines up, oil is then thrown off as the rod
rotates. This oil throw off lubricates the camshaft
lobes, distributor drive gear, cylinder walls, and pis-
ton pins.
The hydraulic valve tappets receive oil directly
from the main oil gallery. The camshaft bearings
receive oil from the main bearing galleries. The front
camshaft bearing journal passes oil through the cam-
shaft sprocket to the timing chain. Oil drains back to
the oil pan under the number one main bearing cap.
The oil supply for the rocker arms and bridged pivot
assemblies is provided by the hydraulic valve tappets
which pass oil through hollow push rods to a hole in the
corresponding rocker arm. Oil from the rocker arm
lubricates the valve train components. The oil then
passes down through the push rod guide holes, and the
oil drain back passages in the cylinder head past the
valve tappet area, and returns to the oil pan.
Fig. 1 Engine Description
Fig. 2 Firing Order
Fig. 3 Engine Identification Number
9 - 54
5.2L ENGINE
ZJ
DESCRIPTION AND OPERATION (Continued)