Camshaft Lobe Lift

Tools Required:

• Cup Shaped Adapter TOOL-6565-AB
• Rotunda Dial Indicator with Bracketry 014-00282

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

1. Remove valve rocker arm cover(s).

2. Remove rocker arm fulcrum bolts, fulcrum and rocker arm.

3. Ensure tappet is seated against cam. Install Rotunda Dial Indicator with Bracketry 014-00282 or equivalent in such a manner as to have ball socket adapter of indicator on top of tappet, or Cup Shaped Adapter TOOL-6565-AB or equivalent on top of push rod and in same plane as tappet or push rod movement.

4. Remove spark plugs.

5. Connect an auxiliary starter switch in starting circuit. Crank engine with ignition switch in OFF position. "Bump" crankshaft over until tappet is on base circle of camshaft lobe. At this point, tappet will be in its lowest position. If checking during engine assembly, turn crankshaft using a socket or ratchet.

6. Zero dial indicator. Continue to rotate crankshaft slowly until tappet is in fully raised position (highest indicator reading).

7. Compare total lift recorded on indicator with specifications.

8. To check accuracy of original indicator reading, continue to rotate crankshaft until indicator reads zero.

   NOTE: If lift on any lobe is below specified service limits, camshaft and tappet operating on worn lobe(s) must be replaced, as well as any tappet showing pitting or having contact face worn flat or concave. Refer to Inspection, Camshaft and Hydraulic Tappets .

9. Remove dial indicator, adapter and auxiliary starter switch.

    CAUTION: After installing rocker arms, do not rotate crankshaft until tappets have had sufficient time to bleed down. To do otherwise may cause serious valve damage. Manually bleeding down will reduce waiting time.

10. Install valve rocker arm cover.

11. Install spark plugs.

Hydraulic Tappet/Lash Adjuster

Tools Required:

• Hydraulic Tappet Leakdown Tester TOOL-6500-E

The hydraulic lash adjusters used in the overhead cam 2.3L I-4 engine are zero-lash hydraulic devices similar in construction and operation to the hydraulic tappets used on push rod engines. They are cleaned, inspected and checked in the same manner as hydraulic tappets. The instructions below apply equally to the lash adjuster and the tappet.

Hydraulic tappet noise may be caused by any of the following:

1. Excessive collapsed tappet gap

2. Sticking tappet plunger

3. Tappet check valve not functioning properly

4. Air in lubrication system

5. Leakdown rate too rapid

6. Excessive valve guide wear

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

   A sticking tappet plunger may be caused by dirt, chips, or varnish inside the tappet. The sticking can be corrected by disassembling the tappet and removing the dirt, chips or varnish that are causing the condition.

   A tappet check valve that is not functional may be caused by an obstruction such as dirt or chips preventing it from closing when the cam lobe is lifting the tappet, or it may be caused by a broken check valve spring.

   Air bubbles in the lubrication system will prevent the tappet from supporting the valve spring load and may 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 pickup tube.

   If the leakdown time is below the specified time for used tappets, noisy operation may result. If no other cause for noisy tappets can be found, the leakdown rate should be checked and any outside the specification should be replaced.

   Assembled tappets can be tested with Hydraulic Tappet Leakdown Tester TOOL-6500-E or equivalent, to check the leakdown rate. The leakdown rate specification is the time in seconds for the plunger to move a specified distance of its travel while under a 22.7 kg (50 lb) load. Test the tappets as follows:

Leakdown Testing

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

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

   NOTE: Tappets cannot be checked with engine oil in them. Only testing fluid can be used.

2. Place tappet in tester, with plunger facing upward. Pour hydraulic tester fluid into cup to a level that will cover 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. A tappet that is satisfactory must have a leakdown rate (time in seconds) within minimum and maximum limits specified.

8. If tappet is not within specification, replace it with a new tappet. If a worn flat tappet is replaced with a new tappet it is recommended that a new camshaft be installed. It is not necessary to disassemble and clean new tappets before testing because oil contained in new tappets is test fluid.

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