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DESCRIPTION & OPERATION
The main oil gallery runs along the left side of the
block. A second oil gallery — the valve lifter/EUP
oil supply gallery — runs along the right side of
the block. The valve lifter bores directly intersect
this right-side gallery, while oil is supplied to the
EUP by six passages drilled from the block’s right
side, through the EUP bore and into the adjacent
valve lifter bore. The six holes along the block’s
right side are closed off with pipe plugs.
Both the left- and right-side oil galleries are drilled
from the front and the rear, but do not meet at the
center. Oil is supplied to the valve lifter/EUP oil
gallery through drilled passages from the No. 2
and No. 5 cam bushings. An annulus in No. 2 and
No. 5 main bearing bores, as well as the groove
in the upper bearing inserts, ensures a high
volume of oil to the lifter/EUP gallery.
Internal fuel supply and return galleries for the
unit pumps are gun-drilled axially, the full length
of the block’s right side just below the unit pump
mounting flange surface.
Current-production cylinder blocks were changed
to accommodate a redesigned oil cooler/filter
mounting arrangement. Early-production engines
used an externally drained Centri-Max
®
filter.
This arrangement has been replaced by the
internally drained Centri-Max PLUS filter on
current-production engines. The major change to
the cylinder block is in the four-bolt oil filter
pedestal mounting pad located at the center left-
hand side of the block. With the elimination of the
externally drained Centri-Max
®
filter, two internal
drain holes are now cast into this mounting pad.
These drain holes allow the Centri-Max
®
PLUS
drain oil to pass directly into the crankcase. The
two 3/4-inch “as-cast” holes are visible inside the
crankcase on either side of the No. 4 main
bearing bulkhead, between Nos. 3 and 4 piston
cooling nozzles. The external oil drain port in the
cylinder block used for the externally drained
Centri-Max
®
filter is covered with a block-off
plate.
5_106_00.bk Page 38 Friday, August 4, 2000 11:17 AM
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