DESCRIPTION & OPERATION
Page 45
There are 45 gear teeth on the crankshaft gear,
90 teeth on the camshaft gear and 48 on the idler
gear. Because the idler gear has 3 more teeth
than the crankshaft gear, the timing marks
(Figure 47) align only once every 16 revolutions
of the crankshaft. This is called a “hunting tooth”
system.
47
Figure 47 — Timing Marks
Because of the addition of an idler gear, the
E-Tech™ engine camshaft rotates in the opposite
direction of the camshaft in the E7 engine. The
additional gearing also changes rotation direction
for the air compressor and the power steering
pump. However, the oil pump drive gear helix has
been changed to keep the same oil pump
direction of rotation.
Air Compressor
E7 and E-Tech™ air compressors have the same
internal components, as the air compressor
functions equally well with either direction of
rotation. There are, however, some external
differences between the engines and air
compressors, which prevent the compressors
from being interchangeable between the two
engines.
The E-Tech™ air compressor benefits from the
22% faster auxiliary shaft speed with quicker
pump-up times, faster air-system recovery and
less operating time under load.
Power Steering Pump
E7 and E-Tech™ engines have the capability of
driving a power steering pump from either the
front or rear of the auxiliary shaft. Naturally, the
direction of rotation of a front power steering
pump is opposite that of a rear power steering
pump. For example, the E-Tech™ auxiliary shaft
has a direction of rotation opposite that of the E7,
while an E7 front-mounted, power steering pump
has the same direction of rotation as an E-Tech™
rear-mounted, power steering pump.
Always refer to part number specification
information when installing a power steering
pump to ensure that the correct part with the
correct direction of rotation is being used.
Installing a power steering pump with the wrong
direction of rotation will result in pump failure and
inoperative power steering.
Vibration Damper Hub
Because the E-Tech™ engine timing gears are
wider than those used in the E7, the E-Tech™
vibration damper hub is 3/8 inch shorter than the
E7 hub (Figure 48). The hubs look the same, but
are different lengths. Always make sure the
correct vibration damper is used for the correct
engine model.
48
Figure 48 — Vibration Damper Hub
1. E-Tech™ Hub
2. E7 Hub
5_106_00.bk Page 45 Friday, August 4, 2000 11:17 AM
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