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TROUBLESHOOTING
CAMSHAFT TIMING AND LOBE
LIFT CHECKS
[213 CH]
Camshaft Timing Check
Correct camshaft timing is essential for proper
engine performance. Incorrect camshaft timing
may be suspected if soon after engine overhaul,
lack of performance, unusual noise or excessive
smoke is reported.
On the E-Tech™ engine, timing marks are
stamped on the flywheel just as they are on the
E7 engine. The E-Tech™ engine, however, does
not have a timing pointer since setting injection
pump-to-engine timing is not necessary. The
flywheel timing marks can be used to check the
camshaft-to-crankshaft timing by looking up
through the hole where the timing pointer would
be located and viewing the timing marks. A pencil
point may be inserted through the timing pointer
hole to easily pinpoint the timing marks on the
scale.
Camshaft timing can be checked using either the
cylinder No. 3 or No. 4 inlet valve. For example
purposes, the No. 3 cylinder will be used in the
steps below.
1. Remove the cylinder head cover over
cylinder No. 3.
2. Locate the inlet valves for No. 3 cylinder (the
sixth valve set from the front of engine). Bar
the engine to position the No. 3 piston at top
dead center (TDC) of the compression
stroke.
3. Loosen (back off) the inlet valve rocker
adjusting screw jam nut. Ensure that the
valve yoke is correctly adjusted. Adjust the
inlet valve to zero lash.
4. Position a dial indicator (magnetic-base
type) probe on the valve spring retainer.
Preload the indicator to 1/2 indicator plunger
travel.
5. Bar the engine in the direction of normal
rotation and carefully observe the direction
in which the indicator needle travels. Use the
dial indicator to determine when the inlet
valve is fully open.
6. Stop rotating the engine when travel of the
dial indicator needle stops. If the dial
indicator needle reverses direction, the full-
open position is passed. Repeat the
procedure if this occurs.
7. Remove the timing hole cover from the
flywheel housing so that the flywheel timing
marks can be viewed. Engine timing should
be approximately 26 degrees. A difference
of approximately 10 degrees indicates that
the crankshaft-to-camshaft timing gears may
be mismatched one tooth.
Camshaft Lobe Lift Check
When diagnosing potential lifter or camshaft
failures, 0.030 inch (0.76 mm) less than the lift of
a new camshaft is considered the minimum
acceptable camshaft lobe lift for used
components. Intake lobe lift differs depending on
the camshaft part number. Camshaft lobe lift is
measured by using a dial indicator at the push
rod with the rocker arm adjusted to zero lash.
5_106_00.bk Page 66 Friday, August 4, 2000 11:17 AM
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