I like the screwdriver and broomstick option! Sometimes the simplest tools are the best ;-)
I still think there's a possibility of it being a valve... though both Mazda and my other mechanic seem to have ruled that out. Then again, we haven't pulled the head either (just the top cover... cam shafts and top of engine look good... but who knows what the valves or cylinder heads look like...). My other mechanic did note that the issue with the timing chain/tensioner did cause the timing to be off... which could have damaged some valves... so I'm not ruling that out yet.
I think the idea of it being "external" could be a possibility... but what? It's not a belt... those have been replaced. Belt tensioner? Maybe. A/C compressor was mentioned earlier... but there's no change in sound whether the A/C is on or off. Alternator? Not likely as a sound like that would likely show it's effects through the charging system. Water pump? Possible. Power steering? Again, not likely as that would likely telescope through the steering column. At one point I even considered that it might be something loose with the exhaust manifold, but no one else has looked at that. What's left that I'm missing?
Then again... if Mazda says it's coming from the "bottom" of the engine... could it be the flywheel, clutch, or some other leading end of the transmission?
Let's see if we can get some more ideas... in the meantime I'm still planning on making some more recordings to see if we can pinpoint this better...
I still think there's a possibility of it being a valve... though both Mazda and my other mechanic seem to have ruled that out. Then again, we haven't pulled the head either (just the top cover... cam shafts and top of engine look good... but who knows what the valves or cylinder heads look like...). My other mechanic did note that the issue with the timing chain/tensioner did cause the timing to be off... which could have damaged some valves... so I'm not ruling that out yet.
I think the idea of it being "external" could be a possibility... but what? It's not a belt... those have been replaced. Belt tensioner? Maybe. A/C compressor was mentioned earlier... but there's no change in sound whether the A/C is on or off. Alternator? Not likely as a sound like that would likely show it's effects through the charging system. Water pump? Possible. Power steering? Again, not likely as that would likely telescope through the steering column. At one point I even considered that it might be something loose with the exhaust manifold, but no one else has looked at that. What's left that I'm missing?
Then again... if Mazda says it's coming from the "bottom" of the engine... could it be the flywheel, clutch, or some other leading end of the transmission?
Let's see if we can get some more ideas... in the meantime I'm still planning on making some more recordings to see if we can pinpoint this better...