My 95 Miata had a knocking sound last year, which went away after a major tune up. Recently the knocking sound came back. The clicking sound also becomes faster as the engine speed increases.
The engine oil turned out to be half empty (
snipped-for-privacy@gmail.com (Tingfang Ji) wrote
The valve cover gasket, a $30 part, is probably leaking. If you have the right tools and ability, it is not difficult to replace. There is also a 50 cent o-ring on what Mazda calls "crank position sensor" and some of us call "cam angle sensor" that should be changed when the valve cover is off. You will need to know how to set ignition timing if you change this. Most miata hobbyists can change both in an evening, working slow.
Anyway, tell the shop you want the valve cover gasket and CAS o-ring changed and it's probably a $200 job. Tell them you want an oil leak fixed and it's at least a $500 job. That's the way it works.
The noise could be the "clatter" common to miata engines. It gets worse when you run low on oil. Change the oil and it should go away.
Thanks for the info. The noise went away after I changed oil and spark plugs and a couple miles of warmup run. I'll try to read up some more posts and fix the valve cover. I'll keep this group posted.
Again, thanks for the information.
Tingfang
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