Lash Adjuster (Tappet) Noise
WARNING: This page is about a different car, the 2020 Jeep Renegade. However, it is still accessible from the selected car via links, so may be relevant.
Proper noise diagnosis is essential in locating the source of an NVH complaint. Locating a hydraulic lash adjuster (tappet) type noise can sometimes be difficult. As a result, an initial misdiagnosis may occur.
Refer to the following chart for possible causes and correction of a lash adjuster (tappet) type noise.
LASH ADJUSTER (TAPPET) NOISE CHART
| POSSIBLE CAUSES | CORRECTION |
|---|---|
| 1. Engine oil level-too high or too low. This may allow aerated oil to enter the adjusters and cause them to be spongy. | 1. Check and correct the engine oil level. |
| 2. Insufficient running time after rebuilding a cylinder head. | 2. Low speed running of up to 1 hour may be required to fully evacuate trapped air from the valve train system. During this time, turn engine off and let set for a few minutes before restarting. Repeat this several times after engine has reached normal operating temperature. |
| 3. Air trapped in the lash adjuster (after 1 hour of run time) or possible faulty lash adjuster. | 3. See below: |
| (a) Check lash adjusters for sponginess while installed in the cylinder head. Depress the lash adjuster. Normal adjusters should feel very firm. Very spongy adjusters can be bottomed out easily. | |
| (b) If the lash adjuster(s) are still spongy, replace the lash adjuster(s). Refer to LIFTER(S), HYDRAULIC, REMOVAL AND INSTALLATION . | |
| 4. Low oil pressure. | 4. See below: |
| (a) Check and correct the engine oil level. | |
| (b) Check the engine oil pressure. Refer to CHECKING ENGINE OIL PRESSURE . | |
| (c) Check for excessive main bearing clearance and correct. Refer to BEARING(S), CRANKSHAFT, MAIN, STANDARD PROCEDURE . | |
| (d) Check for a worn oil pump. | |
| 5. Oil screen in the cylinder head or oil passage to the cylinder head(s) plugged with debris. | 5. Check cylinder head oil passages for blockage. Clean or replace as necessary. |
| 6. Worn valve guide(s). | 6. Measure valve stem-to-guide clearance. Refer to VALVES, INTAKE AND EXHAUST, INSPECTION . |
| 7. Rocker arm ears contacting valve spring retainer. | 7. Visually inspect the alignment of the Variable Valve Actuation (VVAA) plungers. Refer to ASSEMBLY, VARIABLE VALVE ACTUATION, REMOVAL AND INSTALLATION . |
| 8. Rocker arm loose, adjuster stuck or at maximum extension and still leaves lash in the system. | 8. Check for bent valve stem or sticking valve guide. Refer to VALVES, INTAKE AND EXHAUST, INSPECTION . |
| 9. Oil leak or excessive cam bearing wear in the cylinder head. | 9. Check camshaft lobe and bearing journal diameters. Refer to CAMSHAFT, ENGINE, INSPECTION . |
| 10. Collapsed lash adjuster due to debris ingestion. |
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