Auto Tensioner Check; Lash Adjuster Check - Mitsubishi LANCER EVOLUTION-IV 1998 Workshop Manual

Tool mounting hole
Good
MAX
MIN
High-pressure
chamber
ENGINE –
Engine Adjustments

2. AUTO TENSIONER CHECK

(1) Stop the engine from the idle speed and check that the
belt rests within the auto tensioner pulley width.
(2) Remove the drive belt.
(For the removal of the drive belt, refer to P.11-9.)
(3) Fit a spinner handle or similar tool into the tool mounting
hole of the auto tensioner and turn the tensioner clockwise
and counterclockwise to ensure that it does not bind.
(4) If step (1) or (3), or both, have been checked abnormally,
replace the auto tensioner.
(5) Reinstall the drive belt.

3. LASH ADJUSTER CHECK

NOTE
If an unusual knocking noise can be heard immediately after
the engine has started or while it is running and if that is
probably attributable to the lash adjuster, make the following
checks.
(1) Check the engine oil and add or change oil as necessary.
NOTE
(1) If the engine oil level is low, air is taken in through
the oil screen, entering the oil passage.
(2) If the oil level is too high, the cranks agitate oil causing
oil to trap a large amount of air.
(3) Air does not easily separate from a deteriorated oil
that can contain an increased amount of air.
When air trapped in oil for these reasons gets into the
high-pressure chamber of the lash adjuster, the air in
the high-pressure chamber is compressed to shrink the
lash adjuster excessively while the valve is opening,
resulting in an unusual noise occurring. This is the same
symptom developing when the valve clearance is adjusted
to an excessive value.
The problem in this case is gone when air is released
from the lash adjuster.
(2) Start the engine and carry out several cycles (10 or less)
of mild racing*.
If the noise is gone after racing, it indicates that air has
been released from the high-pressure chamber of the
lash adjuster, restoring the lash adjuster to normal
operating conditions.
*: Gradually (extending over a 30-sec. period) increase
the engine speed from idle speed to 3,000 r/min and
then reduce it down to the idle speed gradually
(extending over a 30-sec. period).
NOTE
(1) If the vehicle is parked on a slope for a long time,
the amount of oil in the lash adjuster will decrease,
causing air to get into the high-pressure chamber
when the engine is started.
(2) After the vehicle has been parked for a long time,
oil drains out of the oil passage and it takes a long
time for the oil to reach the lash adjuster. This can
cause air to get into the high-pressure chamber.
11-5