PROBLEM AND SOLUTIONS.docx

PROBLEM AND SOLUTIONS Hydraulic Lash Adjusters - HLA's Pre-Emptive : Regular 3k-mile oil/filter changes, preferably with synthetic. Problem : HLA noise can affect most Mazda engines (Miata/MX5 I4, V6) at any time. The noise is a tap-tap due to non zero-lash between cam lobe & HLA. Symptom : If HLAs are subject to numerous cold stop-start driving or garage-to-drive short trips they may not pump-up with oil properly. This gives the tell-tale tick-tick/tap-tap from an otherwise super-silent V6. More regular oil changes help. If the sound stays after 20mins for several consecutive days then the cause is one or more collapsed HLAs/lifters due to dirt/varnish. Solutions 1. Change oil regularly, every 3k-miles and use a synthetic oil if possible along with oil filter regarding anti-drain back valve quality. 2. A synthetic is known to sludge far less and has better detergents. 3. Should a flush be used, several oil o il changes before & after it are necessary. i. ii. iii. iv. v.

Run synthetic for two oil changes before a flush is performed. Run a flush 10 mins at idle before a change, and then change oil & filter. After 250 miles change the oil & filter again (filter will be full). After 500 miles, put another can of flush through 10 mins at idle, then change the oil &  filter again. After 1500 miles, change oil & filter again. Repeat 1 -4 if noise remains.

HLA Test Procedures In Vehicle Test :   

Remove all spark-plugs. Remove the cam covers front & rear (including VRIS casting etc). Slowly rotate the cam whilst trying to insert a 0.15mm feeler gauge between HLA & cam lobe. Slowly rotating to avoid introducing air into the HLA (which will falsely increase clearance). If the gauge can be inserted then the HLA is collapsed and nearing replacement specification of 0.18mm. Out of Vehicle Test :

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With a HLA in your hand, squeeze it. If it compresses the HLA is to be replaced. Any scuffing of the HLA surface or the cam lobe suggests both must be replaced. In removing any HLA, it must be put back in the place from which it was removed (otherwise the cam-lobe to HLA interface will be different and point-loading will occur increasing temperatures and wear rapidly. In any assessment of HLAs, there is the remote possibility of aerated oil being the cause of  HLA noise - from a faulty sump-pick-up, sump-to-block gasket in the oilpa n, to a faulty oilpump. In the vast majority of cases, HLA noise is dirty oil & filter. Change them both more regularly every 3k miles if necessary, and use a good quality oil.