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PART 8-1-
DIAGNOSIS GUIDE (Continued)
LOSS Of COOLANT
ENGINE FAILS TO REACH
NORMAL OPIRAnNG
TEMPERATURE
NOISY HYDRAULIC
VALVE LlmR
GENERAL ENGINE SERVICE
COOLING SYSTEM
Leaking radiator or water pump.
Loose or damaged hose connec-
tions.
Radiator cap defective.
Overheating.
ENGINE
Cylinder head gasket defective.
TEMPERATURE SENDING
UNIT AND GAUGE
Unit or gauge defective (not indi-
cating correct temperature) or con-
stant voltage regulator defective.
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 lifter(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 (Group 19).
Deposits of gum and varnish
cause similar conditions to exist
which may result in lifter malfunc-
tion. If these conditions are found
to be presept, the lifter should be
disassembled and cleaned in solvent
to remove all traces of deposits.
Air bubbles in the lubricating oil,
8-7
Intake manifold to cylinder head
gasket defective (V-8).
Cylinder head or intake manifold
bolts (V -8) not properly
torqued.
Cylinder block core plugs leak-
ing.
Temperature sending unit leaking.
Cracked cylinder head or block,
or warped cylinder head or block
gasket ·surface.
COOLING SYSTEM
Thermostat inoperative or of in-
correct heat range.
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.
Check for engine oil aeration as
follows:
Check the engine oil level to be
sure it is within specification and
correct as
required.
Be
sure the
~or
red
engine oU
dlpsti~k
Is beiDg used.
Operate the engine at approxi-
mately 1200 rpm until normal oper-
ating temperature is reached. Stop
the engine and remove the oil pres-
sure sending unit. Install a fitting in
this opening with a petcock-type
valve that will permit attachment of
a
1,4
to ¥s -inch-diameter hose of
sufficient length to direct the oil dis-
charge into the oil filler pipe. Close
the valve.
Start the engine and operate it at
approximately 500 rpm for a mini-
mum of S minutes; then, open the
valve slightly to permit a steady dis-
charge of oil. Check the oil flow
for air bubbles.
Increase the engine speed to ap-
proximately 1000 rpm and check for
air bubbles in the oil. To
fa~Uitate
~he~ldng
for air bubbles, direct tbe
oil flow over white paper or
throop
a
pie~e
of transparent tube. Tbe en-
gine should not be opented at ex-
~esslve
speeds or for extended peri-
ods with the oU bleed
atta~bed.
If oil aeration is evident, remove
the oil pan for further test and/ or
inspection of the oil pump intake
system. Perform corrective action as
required to remove air from the lu-
bricating oil.
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