Mazda Tips October, 1998
VIN: JM1NB3532T0705037 Category: B Piston Engine
Repair information: Reference #: 940 Type Desc.: Bulletin
Svc bulletin #: B-005/95
Affected Vin Range
Model Specs
Exc. RX-7 & Millenia S

HLA Noise after long storage

A primary cause of HLA noise is the result of oil drain back to the crankcase during long periods of storage. Category B of the applicable workshop manual contains diagnostic information to determine if the HLA noise is normal or requires replacement. The repair procedure text should be followed to determine if the HLA requires replacement. These instructions will be added to the 1996 workshop manual.

Before performing the HLA inspection and replacement, verify the noise is not the result of carbon accumulation in the combustion chamber.

  1. Check engine oil and replenish if necessary.
    Note: If the oil is dirty, replace the oil. Inform the customer of the need to change oil and that it is not covered by normal vehicle warranty.
  2. Run the engine to normal operating temperature.
  3. Increase the idle to 2,000 - 3,000 RPM and maintain this speed until HLA noise stops or 20 minutes.

NOTE: Do not exceed 20 minutes. Currently the workshop manual states 10 minutes, this will be revised in the 1996 workshop manual. Watch the engine temperature during this operation. If the temperature exceeds normal range, reduce the engine speed to idle until the temperature returns to normal.

If the above method does not eliminate the HLA noise, the following may be the cause of the noise:

  1. Low oil pressure due to clogged oil pump strainer
  2. Oil pump internal problem.
  3. faulty HLA

To locate a noisy HLA use the following procedures.

  1. A .015 feeler gauge can be used to inspect HLA condition. Attempt to insert the feeler gauge between the HLA and valve. If the HLA is good, the feeler gauge will not fit between the cam and the HLA. If the HLA is collapsed, the feeler gauge will fit between the cam and HLA.
    Note: (929 only): During disassembly, when removing the camshafts, wear and light scoring may be present at the third cam journal. This is not a concern and does not result in noise. It is not necessary to replace components for this concern.
  2. After disassembly, the individual HLAs can be inspected by squeezing each one between your fingers to determine if it collapses. If it does move, it is defective, if not, it [original wording cut off here]
  3. For HLAs that fit into rocker arms, with the HLA removed, inspect the tip of the HLA that contacts the valve. If the HLA is good, an "hour glass" wear pattern will appear on the top. If the HLA is collapsed, the HLA tip will have a round peened appearance or an "X" pattern from tapping on the top of the valve stem.
  4. With the HLA removed from the rocker arm, measure the HLA length. If it is less than 20.5 mm k, it should be replaced.

These are tips which can be utilized during HLA inspection, use them as guidelines when inspecting HLA noise concerns. Do NOT replace complete sets of HLAS to cure one noisy HLA.

See service bulletin B-005/95 for illustrations and additional information.

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