Valve Lash Adjuster Noise - Troubleshooting Procedures
NO.: TSB-97-11-002DATE: February, 1997
MODEL: See Below
SUBJECT:
NEW VALVE LASH ADJUSTER NOISE CHECKING AND TROUBLESHOOTING PROCEDURES
PURPOSE
This bulletin contains new information for checking and troubleshooting suspected valve lash adjuster noise for all listed affected vehicles. This information is in addition to the information already in Group 11 of each vehicle's service manuals. Be sure to use the information in this bulletin along with the service manual when diagnosing suspected valve lash adjuster noise.
AFFECTED MODELS
1991-97 3000GT
1992-96 Diamante
1990-97 Eclipse
1992-96 Expo/Expo LRV
1989-97 Galant
1990-92 Mirage
1989-97 Montero
1989 Starion
1990-96 Truck
1989-90 Van/Wagon
SERVICE MANUAL REVISION
The engine troubleshooting chart in the service manuals for all affected models requires one revision concerning the symptom of "Noisy valves". Make the change to all affected manuals as shown.
PROCEDURES
Lash Adjuster Noise Check
If an abnormal noise (chattering or clicking noise), suspected to be a malfunctioning lash adjuster, is produced immediately after starting the engine and does not go away, perform the following checks:
NOTE:
(1) An abnormal noise caused by a malfunctioning valve lash adjuster is produced immediately after starting the engine and changes with the engine speed, no matter what the engine load.
Therefore, if abnormal noise is not apparent just after starting the engine, if it does not change with engine speed, or if it changes with engine load, the noise is not caused by a malfunctioning lash adjuster.
(2) If a lash adjuster malfunctions, the abnormal noise is rarely eliminated by continuing engine warm-up at idle speed. However, the noise may disappear only when lash adjuster seizure is caused by oil sludge in an engine which has not been maintained properly.
1. Start the engine.
2. Check to see if the abnormal noise is produced immediately after starting the engine and that the noise changes with engine speed.
If this noise is not present just after starting the engine or if it does not change with engine speed, a malfunctioning lash adjuster is not the cause of the noise. Investigate for other causes. In this case the lash adjuster is in good condition and the noise is probably caused by other parts in the engine.
3. With the engine idling, change the engine load (shift from N to D, for example). to make sure there is no change in the level of the abnormal noise. If there is a change, suspect a tapping noise caused by a worn crankshaft or connecting rod bearing. In this case, the lash adjuster is in good condition.
4. After the engine is warmed-up, run at idle to check for the abnormal noise.
If the noise is reduced or disappears, make the following checks to see if the noise is caused by the suspected seizure of the lash adjuster. If there is no change in the noise, proceed to Step 5.
a. Cool the engine sufficiently.
b. Turn the crankshaft two turns.
c. Perform the following simple valve lash adjuster check. (The simple lash adjuster checking procedure is shown in more detail at the end of this bulletin.)
^ With the rocker cover removed, push down on each rocker arm. Replace the lash adjuster on any valve where you can push the rocker arm down easily.
^ If the rocker arm cannot be pushed down easily, that lash adjuster is good. Check for other possible causes for the abnormal noise.
NOTE
The lash adjuster can also be checked correctly by using the leak down test found in the particular service manual (Group 11 - Rocker Arm and Camshaft) for the vehicle being diagnosed.
CAUTION
Be sure to bleed the air from a new valve lash adjuster before installing it. For lash adjuster air bleeding procedures, refer to the air bleeding procedures further along in this bulletin or the proper service manual, (Group 11 - Rocker Arm and Camshaft).
5. Run the engine to bleed the lash adjuster system.
6. If the abnormal noise is not eliminated after bleeding the air, do the following checks:
a. Perform the simple lash adjuster check from step 4.c.
^ If only one lash adjuster is bad after doing the simple lash adjuster check (pushing down on the rocker arm), replace that adjuster.
^ If two or more lash adjusters are found abnormal (the rocker arm pushes down easily), then suspect clogged oil passage(s) in the cylinder head. If this is the case, check for clogged oil passages and repair as necessary. If the oil passages are not clogged, replace the lash adjuster.
^ If all the lash adjusters are found to be normal after the simple lash adjuster check (all rocker arms are hard to push down), check for other causes for the abnormal noise.
NOTE
The lash adjuster can also be checked correctly by using the leak down test found in the particular service manual (Group 11 - Rocker Arm and Camshaft) for the vehicle being diagnosed.
CAUTION
Be sure to bleed the air from a new valve lash adjuster before installing it. For lash adjuster air bleeding procedures, refer to the air bleeding procedures elsewhere in this bulletin or in the proper service manual, (Group 11 - Rocker Arm and Camshaft).
7. Start the engine and make sure the abnormal noise is gone. Make sure to do the air bleeding operation.
8. On DOHC engines, replace the lash adjusters using the following procedures.
CAUTION
Before removing the lash adjuster, turn the crankshaft to lower the piston of the cylinder being checked. Otherwise the valve will contact the piston when the valve is pushed down for checking.
In addition, the lash adjuster cannot be removed at the rocker arm lifted by the cam. In this case, turn the crankshaft so the rocker arm in question is not being lifted by the cam.
a. Use the special tool shown in the service manual to push down the valve and remove the roller rocker arm.
b. Pull out the lash adjuster from the cylinder head.
c. Bleed the air from the new adjuster and install it into the cylinder head.
d. Using the special tool, push down the valve and install the roller rocker arm.
NOTE
To install the roller rocker arm, place the pivot end of the rocker arm on the lash adjuster first. Then, push down the valve and place the slipper end of the rocker arm on the valve stem end.
Simple Lash Adjuster Check
1. Stop the engine.
2. Remove the rocker cover.
3. Set the piston of the No. 1 cylinder at top dead center on the compression stroke.
4. Check the rocker arms indicated by the white arrow in the illustration using the following procedure.
FOR ALL EXCEPT THOSE ENGINES WITH Y-SHAPED ROCKER ARMS
Check if the rocker arm can be pushed down when pushing it at the portion just above the lash adjuster.
^ If the rocker arm can be pushed down easily, then the corresponding lash adjuster is defective.
^ If the rocker arm cannot be pushed down (it feels very stiff), the lash adjuster is in good condition. In this case, investigate other causes for the abnormal noise.
FOR THOSE ENGINES WITH Y-SHAPED ROCKER ARMS
NOTE
The Y-shaped rocker arm on the exhaust valve side cannot be pushed down if either of the lash adjusters is in good condition. So, use a feeler gauge to check the lash adjuster using the following procedure.
a. Check if a 0.1 - 0.2 mm leaf of the feeler gauge can be inserted between the valve and the lash adjuster.
b. If the leaf can be inserted, the corresponding lash adjuster is defective.
c. If the feeler gauge leaf cannot be inserted easily, the lash adjuster is good. Investigate other causes for the abnormal noise.
5. Slowly turn the crankshaft 360 degrees clockwise.
6. Follow the same procedure as in Step 4 to check the rocker arms indicated by the black arrows in the illustrations.
Bleeding Air From The Lash Adjuster System
NOTE
^ Parking the vehicle on a grade for a long time may decrease the amount of oil in the lash adjuster, causing air to enter the high pressure chamber when starting the engine
^ After parking for many hours, oil may run out from the oil passage and take time before oil is supplied to the lash adjuster, causing air to enter the high pressure chamber.
^ In the above cases, abnormal noise can be eliminated by bleeding the air from the lash adjuster system.
1. Check the engine oil and add or change as necessary.
NOTE
(1) If the engine oil level is low, air is sucked from the oil screen and enters the oil passage.
(2) If the engine oil level is higher than specification, oil may be stirred by the crankshaft causing the oil to mix with high quantities of air.
(3) If oil is deteriorated, air is not easily separated from the oil, increasing the quantity of air contained in the oil.
(4) If air mixed with oil enters the high pressure chamber inside the lash adjuster from the above causes, air in the chamber is compressed excessively while the valve is open. This results in the production of abnormal noise when the valve is closed. This is the same phenomenon as that observed when the valve clearance is excessive. The lash adjuster can resume normal function when air that has entered the lash adjuster is removed.
2. Idle the engine for one to three minutes to warm it up
3. Repeat the operation pattern, shown in the illustration, at no load to check for abnormal noise. (Normally the noise is eliminated after 10 to 30 repetitions of the operation.) However, if there is no change in the noise after repeating the operation more than 30 times, the noise is probably caused by something other than the lash adjuster.
4. After eliminating the abnormal noise, repeat the operation in the illustration five more times.
5. Run the engine at idle for one to three minutes to make sure the abnormal noise is eliminated and does not return.