Ford COUGAR 1968 Shop Manual page 312

GROUP8
-
Engine
FIG. 47
(Continued)-Engine Diagnosis G u i d e
N O I S Y HYDRAULIC VALVE
LIFTER (Continued)
.
,
at idle speed, place one end of the
Air bubbles in the lubricating oil,
hose near the end of the valve stem
caused by an excessively high or low
and the other end to the ear and oil level, may likewise cause lifter
listen for a metallic noise. Repeat malfunction. A damaged oil pick-up
the procedure on each intake and tube may allow air to be drawn into
exhaust valve until the noisy lifter(s)
the lubricating system.
has been located.
Check for engine oil aeration as
Before replacing a hydraulic valve
follows:
lifter for noisy operation, be sure the
Check the engine oil level to be
noise is not caused by improperly ad- sure it is within specification and cor-
justed valve lash, valve clearance, or rect as required. Be
sure the correct
by worn rocker arms or push rods.
engine oil dipstick is being used.
It should be noted that it is nor- Operate the engine a t approxi-
ma1 for a hydraulic tappet that is mately 1200 rpm until normal opera-
holding a valve open to leak down dur- ting temperature is reached. Stop the
ing extended (overnight) shut-down engine and remove the oil pressure
periods. Such a tappet will be noisy sending unit. Install a fitting in this
for a few seconds following start-up. opening with a petcock-type valve
The most common causes of hy- that will permit attachment of a 114-
draulic valve lifter troubles are dirt, to 318-inch diameter hose of sufficient
gum, varnish, carbon deposits and length to direct the oil discharge into
alr bubbles.
the oil filler pipe. Close the valve.
Dirt in the lifter assembly can pre-
vent the disc valve from seating, or it
Start the engine and operate it at
may become lodged between the
approximately 500 rpm for a mini-
plunger and body surfaces. In either
mum of five minutes; then, open the
case, the lifter becomes inoperative
valve slightly to permit a steady dis-
due to failure to pump-up or be-
charge of oil. Check the oil flow for
cause the internal parts are no longer
air bubbles.
free to function properly. When dirt Increase the engine speed to ap-
is found to be responsible for lifter proximately 1000 rpm and check for
malfunction-, remove the lifter assem- air bubbles in the oil. T o facilitate
bly and thoroughly clean it. Recom-
checking for air bubbles, direct the
mended engineoiland,filterchange4
~ i l f l o w o v e r w h i t e P a P e r o r t h r o u g h
intervals should be followed to a piece of transparent tube. The en-
minimize lifter problems calked by gine should not be operated at
dirt. excessive speeds or lor extended
Deposits of gum and virnish'
periods with the oil bleed attached.
similar conditions to exist which may If oil aeration is evident, remove
result in lifter~malfunction. If these the oil pan for further test and/or
conditions are found to be present, inspection of the oil pump intake
the lifter should be disassembled and system. Perform corrective action as
cleaned in solvent to remove all traces required to remove air from the lubri-
of deposits. cating oil.