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If an abnormal noise (knocking)
that seems to be coming from the lash adjuster is heard
after starting the engine and does not stop, carry out the
following check.
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2.Check that the noise
occurs immediately after the engine is started, and that the
noise changes in accordance with changes in the engine
speed. If the noise does not occur immediately after the
engine is started, or if it does not change in accordance
with the engine speed, the problem is not being caused by
the lash adjusters, so check for some other cause of the
problem. Moreover, if the noise does not change in
accordance with the engine speed, the cause of the problem
is probably not with the engine (In these cases, the lash
adjusters are normal).
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3.While the engine is
idling, check that the noise level does not change when the
engine load is varied (for example, by shifting from N to
D). If the noise level changes, the cause of the noise is
probably parts striking because of worn crankshaft bearings
or connecting rod bearings (In such cases, the lash
adjusters are normal).
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4.After the engine has
warmed up, run it at idle and check if any noise can be
heard. If the noise has become smaller or disappeared,
oil sludge could make the lash adjusters stick. Clean the
lash adjusters (Refer to GROUP 11D - Rocker Arms and
Camshaft - Rocker Arms and Camshaft Inspection ). If not
improved, go to Step 5.
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5.Bleed air from the lash
adjusters (Refer to ).
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6.If the noise has not
disappeared even after the air bleeding, clean the lash
adjusters (Refer to, GROUP 11D - Rocker Arms and
Camshaft - Rocker Arms and Camshaft Inspection ).
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1.Check the engine oil and
replenish or replace the oil if necessary.
note |
- If there is an only small amount of oil,
air will be drawn in through the oil
screen and will get into the oil
passage.
- If the amount of oil is greater than
normal, then the oil will being mixed by
the crankshaft and a large amount of air
may get mixed into the oil.
- If the oil is degenerated, air and oil
will not separate easily in oil, and the
amount of air mixed into the oil will
increase.
- If the air which has been mixed in with
the oil due to any of the above reasons
gets into the high pressure chamber of
the lash adjuster, the air inside the
high pressure chamber will be compressed
when the valve is open and the lash
adjuster will over-compress, resulting
in abnormal noise when the valve close.
This is the same effect as if the valve
clearance is adjusted to be too large by
mistake. If the air inside the lash
adjusters is then released, the
operation of the lash adjusters will
return to normal.
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2.Run the engine at idle for
1 - 3 minutes to let it warm up. 3.With no
load on the engine, repeat the drive pattern shown in the
illustration at left and check if the abnormal noise
disappears (The noise should normally disappear after 10
- 30 repetitions, but if there is no change in the
noise level after 30 repetitions or more, the problem is
probably not due to air inside the lash
adjusters). 4.After the noise has disappeared,
repeat the drive pattern shown in the illustration at left a
further 5 times. 5.Run the engine at idle for 1
- 3 minutes and check that the noise has
disappeared.
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