1.1 Cylinder Block
plates and drain the water Jacket. Then remove the liners and seal rings and blow out all of the passages in the block
with compressed air.
Dry the cylinder liners with compressed air and coat them with oil to prevent rust.
Inspect Cylinder Block
After cleaning and pressure testing, inspect the cylinder block.
Check the block bores as follows:
a. Make sure the seal ring grooves (Fig. 11) are thoroughly clean. Then inspect the grooves and lands for
evidence of pitting and erosion. Two grooves are provided above the air inlet ports of each cylinder bore in the current
block. The single groove formerly below the air inlet ports has been eliminated. However, a cylinder liner seal ring is
required in the upper groove only. The lower groove (on the current block) is provided for the seal ring if inspection
reveals extensive pitting or erosion along the upper land or inner surface of the upper groove. if both grooves are eroded
to the extent that sealing is affected, then the block must be replaced.
b. Measure the entire bore of each cylinder with cylinder bore gage J 5347 (Fig. 12) which has a dial indicator
calibrated in .0001" increments. Use dial bore gage setting tool J 23059 to preset the cylinder bore gage to zero.
Measure each block bore at the positions indicated in Fig. 13, on axis 90 ° apart. If the diameter does not exceed 4.5235
" at position "A", 4.4900 " at position "B" (and a sealing problem hasn't occured), or 4.3595 " at position "C" and "D", then
the block may be reused. Also, the taper and out of round must not exceed .0015 ".
2. Check the top of the block for flatness with an accurate straight edge and a feeler gage. The top surface must not
vary more than .003 " transversely and not over .006 " (3-53 engine) longitudinally.
3. Make sure the cylinder liner counterbores in the block are clean and free of dirt. Then check the depth. The depth
must be .300 " to .302 " and must not vary more than .0015 " throughout the entire circumference. The counterbored
surfaces must be smooth and square with the cylinder bore within .001 " total indicator reading. There must not be over
.001" difference between any two adjacent cylinder counterbores, when measured along the cylinder longitudinal
centerline of the cylinder block.
Check the main bearing bores as follows:
Check the bore diameters with the main bearing caps in their original positions. Lubricate the bolt threads and
bolt head contact areas with a small quantity of International Compound No. 2, or equivalent. Then install and
tighten the bolts to the specified torque. When making this check, do not install the main bearing cap
stabilizers. The specified bore diameter is 3.251 " to 3.252 " (In-Line engine), If the bores do not fall within
these limits, the cylinder block must be rejected.
CAUTION: Main bearing cap bolts are especially designed for this purpose and must not
be replaced by ordinary bolts. Effective with engine serial numbers 6D-27030 and 8D-
1155, a new hexagon head bolt and hardened steel washer are being used in place of
the former 12-point flange type main bearing cap bolt.
NOTE: Bearing caps are numbered to correspond with their respective positions in the
cylinder block. It is imperative that the bearing caps are reinstalled in their original
positions to maintain the main bearing bore alignment. The number of the front main
bearing cap is also stamped on the face of the oil pan mounting flange of the cylinder
block, adjacent to its permanent location in the engine as established at the time of
manufacture. The No. 1 main bearing cap is always located at the end opposite the
Finished and unfinished main bearing caps are available for replacing broken or damaged caps. When fitting a
finished replacement bearing cap, it may be necessary to try several caps before one will be found to provide
the correct bore diameter and bore alignment. If a replacement bearing cap is installed, be sure to stamp the
correct bearing position number on the cap.
NOTE: Use the unfinished bearing caps for the front and intermediate bearing positions.
The finished bearing caps, machined for the crankshaft thrust washers, are to be used in
the rear hearing position.
Main bearing bores are line-bored with the bearing caps in place and thus are in longitudinal alignment.
Bearing bores may be considered properly aligned with one another if the crankshaft can be rotated freely by
hand after new bearing shells have been installed and lubricated and the bearing caps have been secured in
place and the bolts tightened to the specified torque. If a main bearing bore is more