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Hydraulic Lash Adjuster Noise on 1990-93 Mazda 1.6L DOHC
There have been reports of a noise from the top of some 1990-’93 Mazda 1.6L DOHC engines that occur several times faster than crankshaft rotation.
This condition may be caused by restricted oil flow through
the hydraulic lash adjusters (HLAs).
The noise is common after cold engine starts or when returning to idle
after highway driving speeds. To correct the noise condition, HLAs have
been modified to increase oil circulation. If a customer complains of
HLA noise and the engine is within specified range, use the following
If the HLAs require replacement, inform the customer that maintaining
regular oil changes will help prevent this noise from returning.
Installer Repair Procedure:
1) Check engine oil level. If oil level is low, add oil.
the engine and verify the HLA noise. If the noise is present, change
the oil and inform the customer that regular oil changes will help
prevent the noise from returning. If noise is present, proceed to step
3) Increase engine rpm to 2,000-3,000 for 10 minutes.
Return to idle and check again for HLA noise. If noise is still
present, proceed to step 4.
4) Perform engine carbon cleaning as described in Mazda Service Manual.
noise is still present, remove the rocker arm assembly covers and check
for excessive clearance between the camshaft and the HLA. Note: HLA
must not be in compressed position. Turn the cam slowly to avoid air
entering the HLA.
6) If .006˝ (0.15 mm) or more can be inserted between the camshaft and the HLA, replace the HLA.
Some or all of this information was provided by the Automotive
Parts Remanufacturers Association (APRA). For more information on
technical bulletins available through APRA call 703-968-2772 or visit www.AutoBulletins.com.