Lash Adjuster Check
LASH ADJUSTER CHECKWhen a noise (chatter) which is suspected to be caused by a faulty lash adjuster, is heard immediately after starting engine and it persists, inspect as follows.
NOTE:
1. Noise caused by a faulty lash adjuster occurs immediately after starting engine and changes along with the engine revolution but it has nothing to do with the engine load. Accordingly, when the noise does not start immediately after staring engine, when it does not change along with the engine revolution or when it changes along with changes in the engine load, the noise is not caused by the lash adjuster.
2. When the lash adjuster is defective actually, the noise does hardly extinguish even if the engine is warmed up by idling. However, the abnormal noise may disappear only when seizure is caused by oil sludge in the engine whose oil is not maintained properly.
(1) Start engine.
(2) Check if noise starts immediately after starting engine and if the noise changes along with the engine revolution or not.
If the noise does not start immediately after the engine start nor change along with the engine revolution, the noise is caused by other reasons than the lash adjuster and it is necessary to identify the true cause. By the way, when the noise does not change along with the engine revolution, the cause should be considered arising from somewhere other than the engine main unit. (In this case, the lash adjuster is normal.)
(3) Try to change the engine load (Example: Shift between N - D ranges) in the idling state to confirm that the noise level does not change.
If the noise level changes, the chatter is suspected to be caused by the knocking of worn crankshaft bearing or connecting rod bearing. (The lash adjuster is normal in this case too.)
(4) After the engine has warmed up, run the engine at idle and check the noise. If the noise is quiet or has disappeared, the cause is probably that the lash adjusters have seized due to oil sludge, so clean the lash adjusters. If there is no change in the noise level, proceed to step (5).
(5) Bleed air from 'the lash adjuster.
(6) If the noise does not disappear even after air bleeding has been carried out, clean the lash adjusters.
NOTE:
1. When a vehicle has been parked on a slope for a long period of time, oil in the lash adjuster could be reduced so that air may be introduced in the high-pressure chamber when starting engine.
2. After parking a vehicle for a long period of time, oil in the oil path could be reduced so that it may take time before oil is supplied to the lash adjuster and, as a result, air may be inhaled in the high-pressure chamber.
3. In the cases as mentioned above, noise may be eliminated by the air bleeding operation.
1. Inspect engine oil and replenish or exchange oil as required.
NOTE:
1. When the engine oil quantity is not sufficient, air could be inhaled through the oil screen so that air may be introduced into the oil path.
2. When engine oil is reserved beyond the specified quantity, the oil could be agitated with the crankshaft so that a larger amount of air may be mixed in the oil.
3. When oil is deteriorated, it becomes difficult to separate air and oil so that the air amount mixed in oil is likely to increase.
4. If air mixed in oil due to foregoing reasons is introduced into the high pressure chamber of the lash adjuster, air in the high pressure chamber is compressed causing an excessive grasp while the valve is open so that noise generates when the valve closes. This phenomenon is same as the one which is experienced when the valve clearance becomes too large. It should be noted that, if the air introduced in the lash adjuster is released in this case, the lash adjust can restore the normal function.
2. Perform a warm up operation for 1 - 3 minutes in the idling state.
3. Repeat the operation pattern as shown by the left figure under no load and check if noise occurs or not. (Although the noise is eliminated normally after repeating the cycle 10 - 30 times, if there is no change in the noise level after 30 or more cycles, other reasons than the air mixture is suspected.)
4. After confirming elimination of noise, repeat the operation pattern as shown by the left figure for additional 5 cycles.
5. Continue the idling for 1 - 3 minutes to confirm the noise has been eliminated.