Valve Train Analysis

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 (2.3L and 4.0L SOHC engines).

Valve Train Analysis - Rocker Arm and Hydraulic Lash Adjusters, 3.0L Engine
^ Check for loose mounting bolts, studs and nuts.
^ Check for plugged oil feed in the rocker arms, hydraulic lash adjusters or cylinder head.
^ Check for collapsed hydraulic lash adjusters.

Valve Train Analysis - Camshaft Roller Followers and Hydraulic Lash Adjusters, 4.0L SOHC Engines
^ Check for loose mounting bolts on camshaft carriers.
^ Check for plugged oil feed in the camshaft roller followers, lash adjusters or cylinder heads.
^ Check for collapsed hydraulic lash adjusters.

Valve Train Analysis - Push Rods, 3.0L Engines
^ Check for bent push rods and restricted oil passage.

Valve Train Analysis - Valve Springs
^ Check for broken or damaged parts.

Valve Train Analysis - 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 - Valves and Cylinder Head
^ Check for plugged oil drain back holes.
^ Check for worn or damaged valve tips.
^ Check for missing or damaged valve stem seals.
^ Check collapsed valve tappet gap.
^ Check installed valve spring height.
^ Check for missing or worn valve spring seats.
^ Check for plugged oil drain back holes.

Valve Train Analysis - Camshaft Lobe Lift

Valve Train Analysis - Camshaft Lobe Lift, 2.3L
Check the lift of each lobe in consecutive order and make a note of the readings.
1. Remove the valve cover.
2. Remove the spark plugs.
3. Rotate the crankshaft using a breaker bar and a socket attached to the crankshaft pulley bolt. Rotate the crankshaft until the base circle of the camshaft lobe is reached.

Typical Engine With Valve Tappets





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

Valve Train Analysis - Camshaft Lobe Lift, 3.0L
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 hydraulic lash adjuster 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 hydraulic lash adjuster 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 hydraulic lash adjusters.
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, 4.0L SOHC 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.
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





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.

Valve Train Analysis - Hydraulic Lash Adjusters
Hydraulic lash adjuster noise can be caused by any of the following:
^ Excessive hydraulic lash adjuster gap (collapsed)
^ Incorrectly functioning hydraulic lash adjuster
^ Air in lubrication system
^ Excessive valve guide wear
^ Low oil pressure

Excessive collapsed hydraulic lash adjuster gap can be caused by loose rocker arm seat bolts/nuts, incorrect initial adjustment or wear of hydraulic lash adjuster face, or worn roller hydraulic lash adjuster, push rod, rocker arm, rocker arm seat or valve tip. With hydraulic lash adjuster collapsed, check gap between the valve tip and the rocker arm to determine if any other valve train parts are damaged, worn or out of adjustment.

An incorrectly functioning hydraulic lash adjuster can be sticking, caused by contaminants or varnish inside the hydraulic lash adjuster. The hydraulic lash adjuster can have a check valve that is not functioning correctly, which can be caused by an obstruction, such as dirt or chips that prevent the check valve from closing, or a broken check valve spring. A hydraulic lash adjuster with a leakdown time out of specification can cause hydraulic lash adjuster noise. If no other cause for noisy hydraulic lash adjuster can be found, the leakdown rate should be checked and new hydraulic lash adjusters installed if found to be out of specification.

Assembled hydraulic lash adjusters can be tested with a commercially available leakdown tester to check the leakdown rate. The leakdown rate specification is the time in seconds for the plunger to move a specified distance while under a 22.7 kg (50 lb) load.

Air bubbles in the lubrication system will prevent the hydraulic lash adjuster from supporting the valve spring load. This can be caused by too high or too low an oil level in the oil pan or by air being drawn into the system through a hole, crack or leaking gasket on the oil pump screen cover and tube.