Mitsubishi 1992 3000GT, Service Manual

Page: 82 / 1308

ENGINE On-vehicle Service
No.1 No.3 No.5
No.2 No.4
No.6
(2) the engine oil level is higher than the specified
level, agitation of the oil by the crankshaft could cause
a large amount of air to enter the oil.
(3) A deteriorated oil contains a large amount of air, be-
cause the air, once trapped, is not readily separated
from the oil.
If the air trapped due to these causes enters the high
pressure chamber in the lash adjuster, the air in the high
pressure chamber will be compressed while the valve
is in the opened position. The lash adjuster will be drawn
too far in, and will produce noise when the valve closes.
This is the same phenomenon that occurs when the valve
clearance is adjusted to an excessive dimension.
In this case, the normal condition will
restored if the
air escapes from the lash adjuster.
(2) Start the engine and slowly race* it several times (less
than 10 times).
If racing the engine causes the noise to die away, it means
that the air has escaped from the high pressure chamber
of the lash adjuster and that the lash adjuster has regained
its normal functions.
Accelerate the engine from the idling speed to 3,000
rpm slowly (in 30 seconds) and then decelerate it
to the idling speed slowly (in 30 seconds).
NOTE
(1) When the vehicle is parked on a slope for a long
period, the oil in the lash adjuster will decrease. When
the engine is started, the air might enter the high
pressure chamber.
(2) After a long period of parking during which the oil
in the oil passage goes away, it will take some time
before the oil is re-supplied to the lash adjuster. There-
fore, the air could enter the high pressure chamber.
(3) If any abnormal noise is not eliminated by racing, check
the lash adjuster.
1) Stop the engine.
2) Set the engine so that cylinder No. 1 is positioned
at the top dead center of the compression.
3) Press the rocker arm at the area indicated by the
white arrow mark to check whether the rocker arm
is lowered or not.
4) Slowly turn the crankshaft 360 degrees clockwise.
5)
In the same procedure as Step check the rocker
arm at the area indicated by the black arrow mark.
6) Push down the rocker arm at a portion located right
above the lash adjuster. If the rocker arm goes down
readily, the lash adjuster is defective. Replace it with
a new one in accordance with step (4). In addition,
when replacing the lash adjuster, be sure to remove
air positively from the lash adjuster before installation.
Then perform inspection in accordance with steps
(1) through (5) to make sure that there is no abnormal-
ity.
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