Valve Train Analysis - Engine Off

Valve Train Analysis
The following component tests are used to diagnose valve train concerns.

Valve Train Analysis - Engine Off - Valve Cover Removed
Check for damaged or severely worn parts and correct assembly. Make sure correct parts are used with the static engine analysis as follows.

Valve Train Analysis - Engine Off, Valve Tappets, Rocker Arms, Push Rods, 4.2L Engines
^ Check for loose mounting bolts, studs and nuts.
^ Check for plugged oil feed in the rocker arms, push rods, valve tappets or cylinder head.
^ Check for collapsed valve tappet.

Valve Train Analysis - Engine Off, Camshaft Roller Followers and Hydraulic Lash Adjusters, Overhead Camshafts, 4.6L and 5.4L Engines
^ Check for loose mounting bolts on camshaft carriers.
^ Check for plugged oil feed in the camshaft roller followers, hydraulic lash adjusters or cylinder heads.
^ Check for collapsed hydraulic lash adjusters.

Valve Train Analysis - Engine Off, Camshaft - Engines
^ Check for broken or damaged parts.

Valve Train Analysis - Push Rods, 4.2L Engine
^ Check for bent push rods and restricted oil passage.

Valve Train Analysis - Valve Springs
^ Check for broken or damaged parts.
^ Valve Train Analysis - Engine Off, Valve Spring Retainer and Valve Spring Retainer Keys
^ Check for correct seating of the valve spring retainer key on the valve stem and in valve spring retainer.
^ Check for correct seating on the valve stem.

Valve Train Analysis - Engine Off, Valves and Cylinder Head
^ Check for plugged oil drain back holes.
^ Check for worn or damaged valve tips.
^ Check for missing or damaged guide-mounted valve stem seal.
^ Check for damaged hydraulic lash adjuster.
^ Check installed valve spring height.
^ Check for missing or worn valve spring seats.
^ Check for plugged oil metering orifice in cylinder head oil reservoir (if equipped).
^ Static checks (engine off) are to be made on the engine prior to the dynamic procedure.

Valve Train Analysis - Engine Running, Valves and Cylinder Head
^ Check for plugged oil drain back holes.
^ Check for missing or damaged valve stem seals or guide mounted valve stem seals.
^ Check for a plugged oil metering orifice in the cylinder head oil reservoir (4.6L engine only).

If insufficient oiling is suspected, check oil passages for blockage, then accelerate the engine to 1,200 rpm with the transmission in NEUTRAL and the engine at normal operating temperature. Oil should spurt from the rocker arm oil holes such that valve tips and camshaft roller followers are well oiled. With the valve covers off, some oil splash may overshoot camshaft roller followers.

Valve Train Analysis - Camshaft Lobe Lift, 4.2L Engines
Check the lift of each lobe in consecutive order and make a note of the readings.
1. Remove the valve covers.
2. Remove the spark plugs.
3. Remove the rocker arm seat bolts, rocker arm seat and rocker arms.

Typical Engine With Push Rods:

4. Make sure the valve tappet is seated against camshaft. Install the (1) Dial Indicator with Bracketry so the ball socket adapter of the indicator is on top of the hydraulic lash adjuster or the (2) Cup Shaped Adapter is on top of the push rod and in same plane as the push rod movement.
5. Rotate the crankshaft using a breaker bar and socket attached to the crankshaft pulley bolt. Rotate the crankshaft until the hydraulic lash adjuster is on the base circle of the camshaft lobe. At this point, the hydraulic lash adjuster will be in its lowest position.
6. Zero the dial indicator. Continue to rotate crankshaft slowly until the valve tappet is in the fully-raised position (highest indicator reading).
7. To check the accuracy of the original indicator reading, continue to rotate the crankshaft until the base circle is reached. The indicator reading should be zero. If a zero reading is not obtained, repeat the measurement.
8. If the lift on any lobe is below specified service limits, install a new camshaft, and new valve tappets.
9. Install the rocker arm seats, rocker arms and rocker arm seat bolts.
10. Install spark plugs.
11. Install valve covers.

Valve Train Analysis - Camshaft Lobe Lift, 4.6L and 5.4L Engines
Check the lift of each camshaft lobe in consecutive order and make a note of the readings.
1. Remove the valve covers.
2. Remove the spark plugs. Refer to Ignition System.
3. Install the Dial Indicator with Bracketry so the rounded tip of indicator is on top of the camshaft lobe.
4. Rotate the crankshaft using a breaker bar and socket attached to the crankshaft pulley bolt. Rotate the crankshaft until the base circle of the camshaft lobe is reached.

Typical Engine With Camshaft Roller Followers

Typical Engine With Camshaft Roller Followers:

5. Zero the dial indicator. Continue to rotate the crankshaft until the (1) high-lift point of the camshaft lobe is in the fully-raised position (highest indicator reading).
6. To check the accuracy of the original indicator reading, continue to rotate crankshaft until the (2) base circle is reached. The indicator reading should be zero. If zero reading is not obtained, repeat the measurement.
7. If the lift on any lobe is below specified service limits, install a new camshaft and new camshaft roller followers.
8. Install the spark plugs.
9. Install the valve covers.