F 150 4WD Pickup V8-4.6L SOHC VIN W (1998)
Lifter / Lash Adjuster: Testing and Inspection
Leakdown Test
1. Clean hydraulic lash adjuster to remove all traces of engine oil.
NOTE: Valve tappet cannot be checked with engine oil in them. Use only testing fluid.
2. Place valve tappet in tester with plunger facing upward. Pour hydraulic tester fluid into cup to a level that will cover valve tappet. The fluid can be
purchased from the tester's manufacturer. Using kerosene or any other fluid will not provide an accurate test.
3. Place a 7.94 mm (0.312 in.) steel ball provided with tester in plunger cap.
4. Adjust length of ram so pointer is 1.59 mm (0.062 in.) below starting mark when ram contacts tappet plunger to facilitate timing as pointer passes
Start Timing mark.
Use center mark on pointer scale as Stop Timing point instead of original Stop Timing mark at top of scale.
5. Work the valve tappet plunger up and down until valve tappet fills with fluid and all traces of air bubbles have disappeared.
6. Allow ram and weight to force valve tappet plunger downward. Measure exact time it takes for pointer to travel from Start Timing to Stop Timing
marks of tester.
7. A satisfactory valve tappet must have a leakdown rate (time in seconds) within specified minimum and maximum limits.
8. If valve tappet is not within specification, replace it with a new valve tappet. Do not disassemble and clean new valve tappet before testing because
oil contained in the valve tappet is test fluid.
9. Remove fluid from cup and bleed fluid from valve tappet by working plunger up and down. This step will aid in depressing valve tappet plungers
when checking valve clearance.
