Spark plug in oil + knocking/clicking noise

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 (<2 quarters left in 3
months). There was some leak on the body of the engin.

One of the spark plugs (no. 4 at the back) is soaked in oil (plug
body). After changing the spark plug, the noise still persists.

The spark plug wires were changed last year.

Is it possible that the spark plug wires went back again (as indicated
in the following link)? Is the valve gasket leaking?

http://groups.google.com/groups?hl=e...3DN%26tab%3Dwg

I would appreciate any advices and estimate on how difficult is the
job.

Thanks,
Tingfang

(Tingfang Ji) wrote
> Is it possible that the spark plug wires went back again (as indicated
> in the following link)? Is the valve gasket leaking?

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

(merle) wrote in message om>...
> (Tingfang Ji) wrote
> > Is it possible that the spark plug wires went back again (as indicated
> > in the following link)? Is the valve gasket leaking?
>
> 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.