l-10
BASIC ENGINE
l-10
DIAGNOSIS AND TESTING
(Continued)
POSITIVE CLOSED-TYPE VENTILATION
SYSTEM
A malfunctioning closed crankcase ventilation
system may be indicated by loping or rough en-
gine idle. Do not attempt to compensate for this
idle condition by disconnecting the crankcase
ventilation system and making carburetor adjust-
ments.
The removal of the crankcase ventila-
tion system from the engine will adversely
affect the fuel economy and engine ventila-
tion with resultant shortening of engine life.
To determine whether the loping or rough idle
condition is caused by a malfunctioning crank-
case ventilation system, perform the following
test.
CRANKCASE VENTILATION REGULATOR
VALVE TEST
Install d known good regulator valve (PCV) in
the crankcase ventilation system.
Start the engine and compare the engine idle
condition to the prior idle condition.
If the idle condition is found to be satisfactory,
use the new regulator valve and clean the
hoses, fittings, etc.
If the loping or rough idle condition remains
when the good regulator valve is installed, the
crankcase ventilation regulator valve is not at
fault. Check the crankcase ventilation system for
restriction at the intake manifold or carburetor
spacer. If the system is not restricted, further en-
gine component diagnosis will have to be con-
ducted to find the malfunction.
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, re-
place the thrust washers. If the end play is
less than the minimum limit, inspect the
thrust bearing faces for scratches, burrs,
nicks, or dirt.
DIA
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 crankshaft end play will not be
indicated as flywheel runout.
If the clutch face runout exceeds specifica-
tions, remove the flywheel and check for burrs
between the flywheel and the face of the crank-
shaft mounting flange. If no burrs exist, check
the runout of the crankshaft mounting flange.
Replace the flywheel or machine the crankshaft-
flywheel mounting face sufficiently to true up the
surface if the mounting flange runout exceeds
specifications.
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