User Manual

Page 5-10
200 BENCH PROCEDURES
Inspection
If crankshaft journals are worn, out of round, or
tapered, order a new crankshaft or exchange kit
through the MACK parts system. New and
exchange crankshafts are available through
MACK distribution centers. When ordering an E7
crankshaft, be sure to note V-MAC or non V-MAC
application, since crankshafts are not the same.
1. Inspect crankshaft journals for straightness,
out-of-round, taper, and surface finish.
2. Visually check crankshaft for any apparent
cracks, worn journals and damage to
threads, dowel or main drive gear.
3. Magnaflux the crankshaft. This process
requires special equipment and application
methods.
4. Using standard machinist inspection
practice, check crankshaft for straightness.
5. Measure crankshaft journals with a
micrometer. Measure each journal in two
locations, 90 degrees apart, and record
measurements.
6. Check measurements against specifications
in the FITS AND LIMITS section of this
manual.
Crankshaft regrinding by anyone other than Mack
Trucks, Inc. is NOT recommended due to the
tight control required on maintaining geometrical
tolerances, and the hardened characteristics of
the crankshaft journals and journal fillets.
If the crankshaft is not serviceable, both new and
reground crankshafts are available through the
MACK Parts Distribution Centers.
If crankshaft main journals or rod journals are not
a standard size, be sure to use properly sized
bearing inserts. Bearing inserts are marked with a
“P” which follows the part number, and is
stamped on the back side of the bearing insert.
For example, if a journal is 0.010 inch (0.254 mm)
undersize, a 0.010-inch undersize bearing is
required and will be stamped “P10”.
Some crankshafts may have journals which are
0.002 inch (0.0508 mm) undersize. They are
marked by a streak of white paint adjacent to the
journal. Always check journals to ensure using
proper size bearing inserts.
[212 HA] Crankshaft Dowel Pin
Replacement
The “diamond” locating dowel pins used for
installing flywheel to crankshaft have been
replaced by blade-style locating dowel pins. The
diamond pins were dual diameter-type pins.
There was a smaller diameter at the round end
than at the diamond end. There are no changes
in the size of the hole in the flywheel. However,
the crankshaft will have larger holes to accept
blade-style pins.
The blade-type dowel pin was introduced in May
1992, starting with serial No. 2K. You must use
the dowel size that is appropriate for the
crankshaft. (Service old with old, and new with
new.)
Effective May 1993, all E7 engine crankshafts are
equipped with flywheel-to-crankshaft dowel
183GC238 installed in the rear flange. Prior to
this date, only V-MAC engine crankshafts had the
183GC238 dowel. Crankshafts in mechanically
governed engines did not have a dowel pin hole
in the rear flange. However, all E7 engine
crankshafts have always had a crankshaft
manufacturing locator hole in the rear flange. This
hole is approximately 1/2 inch (12.7 mm) in
diameter and 3/8 inch (9.52 mm) deep, and is
used only in the manufacturing process.
The flywheel locating dowel hole — located
directly opposite the manufacturing locator hole —
is approximately 9/16 inch (14.29 mm) in
diameter by 7/8 inch (22.23 mm) deep in
crankshafts made since May 1992 using dowel
183GC238. V-MAC crankshafts made prior to
May 1992 have a flywheel locating dowel hole
1/2 inch (12.7 mm) in diameter by 7/8 inch
(22.23 mm) deep for dowel 183GC221.
5-101.bk Page 10 Friday, March 17, 2006 11:05 AM