Valve Train Analysis

Engine

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 - Camshafts

- Check for broken or damaged parts.

- Check for loose mounting bolts on camshaft caps.

Valve Train Analysis - Camshaft Roller Followers and Hydraulic Lash Adjusters - 3.0L Engine

- Check for broken or damaged parts.

- Check for incorrectly installed roller followers.

- Check for collapsed hydraulic lash adjusters.

Valve Train Analysis - Valve Tappet - 2.5L and 3.5L Engines

- Check for valve tappet face wear.

- Check for excessive valve tappet clearance. Refer to Valve Clearance Check.

Valve Train Analysis - Valve Springs, Valve Spring Retainers and Valve Spring Retainer Keys

NOTE: Valve tappets must be removed on 2.5L and 3.5L engines.

- Check for broken or damaged parts.

- 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 - Valves and Cylinder Head

NOTE: Valve tappets must be removed on 2.5L and 3.5L engines.

- 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 missing or worn valve spring seats.

- Check for plugged oil metering orifice in cylinder head oil reservoir (if equipped).

Valve Train Analysis - Camshaft Lobe Lift

Check the lift of each camshaft lobe in consecutive order and make a note of the readings.

1. Remove the spark plugs.

2. Install the Dial Indicator Gauge with Holding Fixture so the rounded tip of the Dial Indicator Gauge is on top of the camshaft lobe and on the same plane as the valve tappet (2.5L and 3.5L) or hydraulic lash adjuster (3.0L).

3. Rotate the crankshaft using a breaker bar and socket attached to the crankshaft pulley retainer bolt. Rotate the crankshaft until the base circle of the camshaft lobe is reached.





4. Zero the Dial Indicator Gauge. Continue to rotate the crankshaft until the high-lift point of the camshaft lobe is in the fully-raised position (highest indicator reading).

5. To check the accuracy of the original indicator reading, continue to rotate crankshaft until the base circle is reached. The Dial Indicator Gauge reading should be zero. If zero reading is not obtained, repeat Steps 1 through 6.

6. If the lift on any lobe is below specified service limits, install a new camshaft and camshaft roller followers or valve tappets.

7. Install the spark plugs.