Hydraulic Roller Lifter Assembly
NOTE:
The 5.0L engine uses hydraulic roller lifters for reduced fiction on camshaft lobes.
NOTE:
Before replacing lifter for noisy operation, be sure it is not caused by improper collapsed lifter gap, worn rocker arms, pushrods or valve tips. If lifter is stuck, use puller or magnet.
- Lifters must be reinstalled in original locations. Clean and inspect, but DO NOT mix components or positions. Parts are select-fitted and not interchangeable. If lifter is sticking, disassemble and clean dirt, metal chips or varnish from components.
- If plunger is not free in lifter body, replace lifter. Plunger should drop to bottom of body by its own weight when assembled dry. Assemble and check operation by pressing down on cap.
- Inspect lifter roller lobe contact area. Surface must not have pits and roll freely with no binding. Replace any lifter with scored or worn body surface. Inspect related cam lobe(s) for proper lobe lift. Replace camshaft and lifters if lobe(s) worn.
- Check lifter-to-bore clearance. Standard clearance is .0005-.0020" (.0127-.051 mm). Standard diameter of lifter is .8422-.8427" (21.392-21.405 mm). Standard lifter bore diameter is .8435-.8445" (21.425-21.450 mm). Check lifter leak-down rate. Replace any lifter not within specification. See Fig 1.Fig 1: Exploded View of Hydraulic Lifter Assembly. Check lifter leak-down rate with test fluid in lifter.NOTE: When performing leak-down test, lifters cannot be checked with engine oil; test fluid must be used.
- Coat lifter base with Molykote. When installing, ensure lifter is on base circle of camshaft and straight in relation to lobe. Tighten lifter guide and retainer to specification. See Fig 2. Tighten rocker arm bolt to specification. Coat gasket surfaces with RTV sealer and install valve covers and intake manifold.