Specifications

PART 1-1-GENERAL ENGINE SERVICE
1-7
ENGINE TROUBLE DIAGNOSIS GUIDE (Continued)
ENGINE FAILS TO REACH
NORMAL OPERATING
TEMPERATURE
TEMPERATURE SENDING
UNIT AND GAUGE
Unit or gauge defective (not indi-
cating correct temperature) or con-
stant voltage regulator defective.
COOLING SYSTEM
Thermostat inoperative or of in-
correct heat range.
NOISY HYDRAULIC
VALVE LIFTER
A noisy hydraulic valve lifter can
be located by operating the engine at
idle speed and placing a finger on the
face of the valve spring retainer. If
the lifter is not functioning prop-
erly, a shock will be felt when the
valve seats.
Another method of identifying a
noisy lifter is by the use of a piece
of hose. With the engine operating
at idle speed, place one end of the
hose near the end of the valve stem
and the other end to the ear and
listen for a metallic noise. Repeat
this procedure on each intake and
exhaust valve until the noisy lift-
er(s) has been located.
The most common causes of hy-
draulic valve lifter troubles are dirt,
gum, varnish, carbon deposits, and
air bubbles.
Dirt in the lifter assembly can
prevent the disc valve from seating,
or it may become lodged between
the plunger and body surfaces. In
either case, the lifter becomes inop-
erative due to failure to "pump-up,"
or because the internal parts are no
longer free to function properly.
When dirt is found to be respon-
sible for lifter malfunction, remove
the lifter assembly and thoroughly
clean it. Recommended engine oil
and filter change intervals should be
followed to minimize lifter prob-
lems caused by dirt.
Deposits of gum and varnish
cause similar conditions to exist
which may result in lifter malfunc-
tion. If these conditions are found
to be present, the lifter should be
disassembled and cleaned in solvent
to remove all traces of deposits.
Air bubbles in the lubricating oil,
caused by an excessively high or
low oil level, may likewise cause
lifter malfunction. A damaged oil
pick-up tube may allow air to be
drawn into the lubricating system.
To check for the presence of air,
remove a valve rocker arm cover and
note the condition of the oil as it flows
from the valve rocker arm shaft as-
sembly. Perform corrective action as
required to remove air from the lubri-
cating oil.
SILENT VALVE
MECHANISM
MALFUNCTIONING OR
SLUGGISHLY OPERATING
ECCENTRIC
A properly operating eccentric
should compensate for variation in
the adjustment screw within 30 sec-
onds at approximately 1000 engine
rpm.
To determine if the eccentric is
operating correctly, operate the en-
gine at 1000 rpm. Slowly vary the
position of the adjustment screw to
change the operating range of the
eccentric. The eccentric should move
in and out to compensate for the
turning of the adjustment screw with-
in 30 seconds. If it does not, check
to see if the eccentric is properly in-
stalled and/or if it has reached the
limit of its travel, with the eccentric
against the stop on the rocker arm.
When the screw is turned, the valve
may be held open for a short period
of time. This is normal and will
close after the eccentric has oper-
ated long enough to compensate. If
it does not compensate in the speci-
fied time, replace the eccentric.
EXCESSIVE VALVE NOISE
Check the adjustment of the rock-
er arm eccentric.
If the eccentric is out of adjust-
ment, check the related parts for ab-
normal wear, then adjust the eccen-
tric. Check the eccentric operation as
explained under "Malfunctioning or
Sluggishly Operating Eccentric." If
the operation is unsatisfactory, re-
place the parts as necessary.