TRUCK SERVICE MANUAL
Ampere-turns is defined as the amperage flowing
through the coil, multiplied by the number of turns in the coil.
Viscous dampers operate on a different principle and are not
Most coils contain four turns and therefore only 700 amperes
as critical in their operation. Due to design, operation over a
need to be applied with DC equipment, or 850 amperes with
greater variation in load and mass is possible
1. Spray damper with Spotcheck Developer, Type SKD-
c. Apply one and one-half percent wet solution while
NF, or equivalent. Place damper in oven heated to 200 deg.
current is on. Make visual inspection after each application of
F [93 deg. C]. Allow damper to reach oven temperature.
2. Remove damper from oven and inspect for oil
2. Assemble cap to rod and alternately tighten nuts to
smudges or fluid leakage. If oil smudges appear, discard
operating tension as described in Table 1-1 (19).
3. Check crankpin bore with a dial bore gauge or inside
3. Check damper for eccentricity and wobble after
installation. Refer to Group 14. An alternate but less effective
method for inspecting viscous dampers is by shaking damper.
a. On 2 bolt connecting rods the bore diameter must be
Movement of loose pieces may be felt or heard if fluid has
within 3.2722 to 3.2736 inch [83.114 to 83.149 mm] up to 30
been lost. Tap front face at outside and inside seal. If seal is
deg. on either side of parting line. Fig. 1-8.
broken, a hollow sound will be heard at break. The viscous
damper cannot be balanced in the Field; if out of balance is
suspected, install a new damper.
Vibration Damper Mounting Flange
1. Check damper mounting capscrew hole threads.
2. Maximum eccentricity of mounting flange, measured
on outside diameter of pilot, should not exceed 0.004 inch
[0.10 mm] total indicator reading. Wobble of flange, measured
at 2-3/4 inch [69.85 mm] radius, should not exceed 0.003 inch
[0.08 mm]. The above readings are to be taken after
assembly to engine. Crankshaft must be kept to front or rear
thrust limit while wobble is checked.
1. Magnaflux all connecting rods, caps and bolts; discard
if cracks are detected.
Note: Be sure rod and cap are kept mated at all times.
a. Check rods for cracks with 1800 ampere current AC
equipment or 1500 ampere current DC or rectified AC
equipment longitudinally between plates.
b. Check rods for cracks with 3000 to 3400 ampere-turns
with AC equipment or 2600 to 2800 ampere-turns with DC or
Pin Bushing Bore
rectified AC equipment in a coil. Pay particular attention to
shaded critical areas shown in Fig. 1-6.
Defect In Rod
Fig. 1-6 (V40114). Connecting rod specifications.