Lifter / Lash Adjuster: Testing and Inspection
When 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) Check the noise in the idling state after warm up operation When the noise diminishes or extinguishes, the cause is considered to be related with a seizure of lash adjuster due to oil sludge, etc. If it is the case, proceed to the step (5).
1) Cool down the engine sufficiently.
2) Turn the crankshaft two turns.
3) Check the lash adjuster with the simplified inspection.
- Replace the lash adjuster which was recorded during the simplified lash adjuster inspection (the one of which the rocker arm can be pushed down easily).
- When all lash adjusters have been discovered to be normal as a result of the simplified lash adjuster inspection (any rocker arms cannot be pushed down easily), check for other causes of the noise.
Caution When installing a new lash adjuster, make sure to perform a positive air bleeding of the part as an independent component.
(5) Bleed air from the lash adjuster.
(6) When the noise persists even after the air bleed operation, inspect as follows.
1) Perform the simplified inspection of lash adjuster.
- When only one lash adjuster has been recorded (as the one of which the rocker arm can be pushed down easily) during the simplified lash adjuster inspection, replace the lash adjuster.
- When more than two lash adjusters have been recorded (as the ones of which the rocker arms can be pushed down easily) during the simplified lash adjuster inspection, it is suspected that the oil path on the cylinder head is clogged.
Check if the oil path is clogged or not and repair if necessary. When it is not clogged, replace the lash adjusters.
- When all lash adjusters have been proved to be normal (the rocker arms cannot be pushed down easily) as a result of the simplified lash adjuster inspection, check for other causes of the noise.
Caution When installing a new lash adjuster, make sure to perform a positive air bleeding of the part as an independent component.
(7) Start engine and confirm that the noise has been extinguished. Perform the air bleed operation if necessary.
1. Stop engine.
2. Remove the rocker cover.
3. Set No. 1 cylinder at the compression top dead center.
4. Inspect the rocker arms which are indicated with white arrows in the left figure, as explained below.
(1) Check if the rocker arm can be pushed down by pushing the rocker arm at the section directly above the lash adjuster.
- When the rocker arm can be pushed down easily, record the corresponding lash adjuster on a memo.
- When the rocker arm cannot be pushed down (a hard resistance is felt), it means the lash adjuster is normal and it is necessary to check for other causes of the noise.
NOTE Regarding the Y shape rocker arms at the exhaust valve side, even if the lash adjuster at one side is faulty, the rocker arm cannot be pushed clown so far as the other lash adjuster is normal.
Therefore, it is necessary to check using a feeler gauge as follows.
(1) Check if a 0.1 - 0.2 mm (0.0039 - 0.0079 inch) thick feeler gauge can be inserted between the valve and the lash adjuster or not.
(2) If the feeler gauge can be inserted easily, record the corresponding lash adjuster.
(3) When the feeler gauge cannot be inserted easily, the lash adjuster is normal and it is necessary to check for other causes of the noise.
5. Slowly turn the crankshaft in the clockwise direction by 360.
6. Inspect the rocker arms indicated with black arrows in the figure in the same way as step (4) above.
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.