Engine Running, Leakdown Testing

NOTE: Do not mix parts from different hydraulic lash adjusters. Parts are select-fit and are not interchangeable.

1. Clean the hydraulic lash adjuster to remove all traces of engine oil.
2. Place the hydraulic lash adjuster in the tester with the plunger facing upward. Pour the hydraulic tester fluid into the cup to a level that will cover the hydraulic lash adjuster. The fluid can be purchased from the tester's manufacturer. Using kerosene or any other fluid will not provide an accurate test.

NOTE: The hydraulic lash adjuster cannot be checked with engine oil in them. Use only testing fluid.

3. Adjust the length of the ram so that the pointer is 1.59 mm (0.062 inch) below the starting mark when the ram contacts the tappet plunger to facilitate the timing as the pointer passes the Start Timing mark.

Use the center mark on the pointer scale as the Stop Timing point instead of the original Stop Timing mark at the top of scale.

4. Work the lash adjusters plunger up and down until the hydraulic lash adjuster fills with fluid and all traces of air bubbles have disappeared.
5. Allow the ram and weight to force the hydraulic lash adjuster plunger downward. Measure the exact time it takes for the pointer to travel from the Start Timing to Stop Timing marks of the tester.
6. A satisfactory hydraulic lash adjuster must have a leakdown rate (time in seconds) within the specified minimum and maximum limits.
7. If the hydraulic lash adjuster is not within the specification, replace it with a new hydraulic lash adjuster. Do not disassemble and clean new hydraulic lash adjuster before testing because the oil contained in the new hydraulic lash adjuster is test fluid.
8. Remove the fluid from the cup and bleed the fluid from the hydraulic lash adjuster by working the plunger up and down. This step will aid in depressing the lash adjuster plungers when checking the valve clearance.