Hydraulic Valve Tappets

Valve tappets (6500) should be kept in proper sequence so that they can be installed in their original position. Inspect and test each valve tappet separately so as not to intermix. If any part of the valve tappet needs replacing, replace the entire assembly.

Cleaning

Thoroughly clean all the parts in clean solvent and wipe them with a clean, lint-free cloth.

Inspection

Inspect the parts and discard the entire valve tappet if any part shows pitting, scoring or excessive wear. Replace the entire assembly if the plunger is not free in the body. The plunger should drop to the bottom of the body by its own weight when assembled dry and check ball assembly removed.

Assemble the valve tappet and check for freeness of operation by pressing down on the plunger. The valve tappets can also be checked with a hydraulic tester to test the leak-down rate. Follow the instructions of the test unit manufacturer or Leak-Down Testing in this section.

Valve, Flat, Tappet Wear

Leak-Down Testing

Remove tappets as outlined in Section 03-01A (4.9L SFI), Section 03-01B (5.0L and 5.8L MFI), Section 03-01C (7.5L MFI) or Section 03-01D (7.3L diesel).

1. NOTE: Do not mix parts from different valve tappets. Parts are select-fitted and are not interchangeable.

   NOTE: Valve tappet cannot be checked with engine oil in it. Only testing fluid can be used.

   Disassemble and clean valve tappet to remove all traces of engine oil.

2. Place valve tappet in tester, with plunger facing upward. Pour hydraulic tester fluid into cup to a level that will cover valve tappet assembly. The fluid can be purchased from manufacturer of tester. Using kerosene or any other fluid will not provide an accurate test.

3. Place a 7.94mm (5/16-inch) steel ball provided with tester in plunger cap.

   

4. Adjust length of ram so that pointer is 1.59mm (1/16 inch) below starting mark when ram contracts 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 tappet plunger up and down until tappet fills with fluid and all traces of air bubbles have disappeared.

6. Allow ram and weight to force tappet plunger downward. Measure exact time it takes for pointer to travel from start timing to stop timing marks of tester.

7. NOTE: Refer to the Specifications portion of Section 03-01A (4.9L SFI), Section 03-01B (5.0L and 5.8L MFI), Section 03-01C (7.5L MFI) or Section 03-01D (7.3L diesel) for hydraulic lifter leak-down rates.

   A valve tappet that is satisfactory must have a leak-down rate (time in seconds) within minimum and maximum limits specified.

8. Remove fluid from cup and bleed fluid from valve tappet by working plunger up and down. This step will aid in depressing tappet plungers when checking valve clearance.

9. If a valve tappet is not within specifications:

   • Remove camshaft (6250) as outlined in Section 03-01A (4.9L SFI), Section 03-01B (5.0L and 5.8L MFI), Section 03-01C (7.5L MFI) or Section 03-01D (7.3L diesel).
   • Inspect camshaft and check condition and cam lobe lift as outlined in this section.
   • Replace defective valve tappets with new ones. It is not necessary to disassemble and clean new valve tappets to test them since they are shipped with testing fluid.