Miata timing belt replacement

treilly2

I had the dealer do the 60K service on my 1996 Miata at 59K, including replacement of the timing belt and aux. dive belt. On the day I picked it up, the values were noticeably tapping intermittently (the engine had never made a sound previously). The valve tapping wasn't constant, but would become highly noticeable and then quiet down. Took it back to the dealer and they supposedly adjusted the values and said it was probably just loose carbon causing it. Still have the same problem. Any suggestions?

Mr_Shiftright

Sounds like they gave you the "sunshine treatment" (left the car out in the lot all day). Loose carbon is a nonsense answer. At least get a straight answer from them.....geez...loose carbon.....

ANYWAY---I can't recall if they have to disturb the valve adjustment on that car to change the timing belt, i.e., if the camshaft comes off on that car for this job....if it does, then the valve adjustment they did might not have been very careful. Probably no harm in a little valve noise, but if it wasn't that way, perhaps they could dial it in a little better for you.

daysailer

Intermittent valve noise, particularly when cold, is not uncommon in Mazda (and other) engines that employ hydraulic lash adjusters (HLA). The are similar in concept to hydraulic lifters in pushrod engines but they are incorporated into the rocker arms and are much smaller and lower in mass. HLAs tend to be sensitive to oil quality and viscosity because their oil passages and volume are small and Mazdas seem more prone to noise than some other HLA designs. I have 3 Mazdas and an Acura, all of which have HLAs but noise is much more common in the Mazdas (and the Acura is the oldest). I can't explain why the onset of noise would occur with a belt change, it may be a coincidence. In my '92 Miata, when noise occurs it is usually about when an oil change is due and it is quiet after a change. My MPV is more problematic and I have twice resorted to additives (Gunk Valve Medic) just prior to oil change to good effect (although chemical "repairs" give me pause). A change to a broader range multi-vis oil (e.g. 5w30 in lieu of 10W30) may also help, particularly in cold weather.

Try changing the oil.