AboutMp2 Expertise I prefer to answer questions relating to the Miata since this has been my area of specific
expertise since 1991. I can answer questions relating to the other Mazda models however
some limitation of expertise may reduce my accuracy.
Experience Mazda technician since 1987, shop owner and specialty are regarding the Miata since 1991 covering mechanical, electrical, trim and body. Specializing specifically in drivability concerns.GKHS 1985, BVC 1987, MNA 1989, ASE Master Technician Mechanical 1995, ASE Master Body/Paint/Collision 1996
Education/Credentials GKHS 1985, BVC 1987, MNA 1989, ASE Master Technician Mechanical 1995, ASE Master Body/Paint/Collision 1996
Question My wife have a Mazda 3, 2004 with 60,000km.\r\nwhen running idle, sometime I have a wear sound coming out of the engine (like knocking). as soon as I increase engine speed, the sound goes away. I may think it is from an hydraulic lifter but how I can be sure ? how many of them ? can I take the valve cover off and run the engine to check it out ? do I need to replace all them ? can I visually see which one is wrong ? quick stop at the Mazda dealer, they told her the engine need to be replace.......!. I would not bet on their honesty. thanks a lot for your help. Denis
Answer Not my area of expertise however, hydraulic valve lifters on overhead cam Mazdas can capture air bubbles which cause the lifter(s) to collapse. The problem is remedied once the oil pressure forces the air bubble(s) out and the hydraulic state is restored. To avoid this issue change the oil every 3k/3month (conventional oil) or switch to a full synthetic (we use Valvoline) changed every 5k/5months. Depending upon your climate use 5w-20 (colder regions) or 5w30 (average) or 5w40 (hotter regions). Also use a Mazda oil filter or a K&N filter. These filters are designed to prevent back flow when the engine is shut off. Back flow causes the oil galleys to drain back through the pump when the engine is off. Once restarted the oil pushes air in front of the oil back into the galleys and thus into the lifters which can form bubbles until purged. Hence your problem.
Liken it to drinking out of a straw, some air always comes first.
Unless you overheated the motor or ran low or used something other than oil or ran out of oil or left the same oil in for way too long, I would seriously doubt the need for a new motor at 60km (under 40,000 miles)
