Engine: Diagnosis And Testing; Camshaft Lobe Lift; Compression Test; Flywheel Face Runout, Camshaft End Play - Ford VSG-411 Service Manual

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Basic Engine
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DIAGNOSIS AND TESTING
CAMSHAFT LOBE LIFT
Check the lift of each lobe in consecutive order and make a note
of the readings.
1. Remove the air cleaner and the valve rocker arm cover.
2. Remove the valve rocker arm shaft assembly as detailed in the
pertinent section.
3. Make sure the push rod is in the valve lifter socket. Install a
dial indicator in such a manner as to have the ball socket
adapter of the indicator on the end of the push rod and in the
same plane as the push rod movement (Figure 6).
FIG. 6 Testing Camshaft Lobe Lift
4. Connect an auxiliary starter switch in the starting circuit.
Crank the engine with the ignition switch OFF. Bump the
crankshaft over until the tappet or lifter is on the base circle of
the camshaft lobe. At this point, the push rod will be in its
lowest position.
5. Zero the ' dial indicator. Continue to rotate the crankshaft
slowly until the push rod is in the fully raised position (highest
indicator reading).
6. Compare the total lift recorded on the indicator with
specifications.
7. To check the accuracy of the original indicator reading, con-
tinue to rotate the crankshaft until the indicator reads zero. If
the lift on any lobe is below specified wear limits, the
camshaft and the valve lifters operating on the worn
lobe(s) must be replaced.
8. Remove the dial indicator and auxiliary starter switch.
9. Install the rocker arm shaft assembly as detailed under Re-
moval and Installation.
10. Install the valve rocker arm cover and the air cleaner.
COMPRESSION TEST
COMPRESSION GAUGE CHECK
1. Be sure the crankcase is at the proper level and the battery is
properly charged. Operate the engine for a minimum of 30
minutes at 1200 rpm or until the engine is at normal operating
temperature. Turn the ignition switch off; then remove all the
spark plugs.
2. Set the carburetor throttle plates and chc~ke plate in the wide
open position.
3. Install a compression gauge in No. 1 cylinder.
4. Install an auxiliary starter switch in the starting circuit. Using
the auxiliary starter switch, crank the engine (with the ignition
switch off) at least five compression strokes and record the
highest reading.
Note the approximate number of compression strokes required
d
to obtain the highest reading.
5. Repeat the test on each cylinder as was required to obtain the
highest reading on the No. 1 cylinder.
TEST CONCLUSION
The indicated compression pressures are considered normal if
the lowest reading cylinder is within 75% of the highest. Refer to
the following example and Figure 7.
Seventy-five percent of 140, the highest cylinder reading, is
105. Therefore, cylinder No. 7 being less than 75% of cylinder
No. 3 indicates an improperly seated valve or worn or broken
piston rings.
If one or more cylinders read low, squirt approximately one (1)
tablespoon of engine oil on top of the pistons in the low reading
cylinders. Repeat compression pressure check on these cylinders.
1. If compresison improves considerably, the piston rings are at
fault.
2. If compression does not improve, valves are sticking or seat-
ing poorly.
3. If two adjacent cylinders indicate low compression pressures
' and squirting oil on the pistons does not increase the compres-
sion, the cause may be a cylinder head gasket leak between the
cylinders. Engine oil and/or coolant in the cylinders could
result from this problem.
It is recommended the following quick reference chart be used
when checking cylinder compression pressures. The chart has
been calculated so that the lowest reading number is 75% of the
highest reading.
EXAMPLE
After checking the compression pressures in all cylinders, it was
found that the highest reading obtained was 196 psi. The lowest
pressure reading was 155 psi. The engine is within specifications
and the compression is considered satisfactory.
CRANKSHAFT END PLAY
1. Force the crankshaft toward the rear of the engine.
2. Install a dial indicator so that the contact point rests against the
crankshaft flange and the indicator axis is parallel to the
crankshaft axis .
3. Zero the dial indicator. Push the crankshaft forward and note
the reading on the dial.
4. If the end play exceeds the wear limit, replace the thrust
washers. If the end play is less than the minimum limit,
inspect the thrust bearing faces for scratches, burrs, nicks, or
dirt.
FLYWHEEL FACE RUNOUT
Install a dial indicator so that the indicator point bears against
the flywheel face. Turn the flywheel, making sure that it is full
forward or rearward so that the crankshaft end play will not be
indicated as flywheel runout.
If the clutch face runout exceeds specifications, remove the
flywheel and check for burrs between the flywheel and the face of
the crankshaft mounting flange. If no burrs exist, check the runout
of the crankshaft mounting flange. Replace the flywheel, or ma-
chine the crankshaft-flywheel mounting face sufficiently to true up
the surface if the mounting flange runout exceeds spec"fications.
Replace it or reinstall it on the flywheel.
CAMSHAFT END PLAY
Push the camshaft toward the rear of the engine. Install a dial
indicator so that the indicator point is on the camshaft sprocket
attaching screw or gear hub. Zero the dial indicator. Position a
large screwdriver between the camshaft sprocket and the cylinder
head. Pull the camshaft forward and release it. Compare the dial
indicator reading with specifications. If the end play is excessive,
replace the thrust plate retaining the camshaft. Remove the dial
indicator.