At ~3k rpm (and as far as I can tell, only at 3k rpm) I get this horrible marble in a coffee can kind of rattle. It doesn't seem to be exhaust related, or anything else bolted to the outside of the engine, for that matter. Very hard to troubleshoot solo but it happens in gear or in neutral, clutch in or out makes no difference. The rest of the noise in the clip is just typical 225k Miata lifter tick, my phone mic is more sensitive than expected. Wait a few seconds and you'll hear it.
Also - it's pretty stock engine wise, with the only significant modifications being a lightweight flywheel and clutch (SuperMiata) It also has a racing beat intake and Jackson racing header. Mazdacomp engine mounts, so things aren't too rattly in general.
Engine sounds good, I'd want to take a look at the clutch and flywheel personally. There might be something there.
In reply to KyAllroad :
That was my first thought too, but I really don't want to pull the transmission out. It's weird because it seems like a harmonic thing.
What I really need is someone to sit in it and hold the revs at the right spot so I can listen to the bell housing with my stethoscope, but the kids aren't quite old enough for that haha.
Ohhhhhh I wonder if it's the starter...
That doesn't sound like an engine thing. It sounds really light and tinny like a heat shield or a bracket. More sheet metal that a bracket is likely to be. I'd look for loose fasteners and maybe go around under the hood and under the car whacking stuff with a heavy rubber dead blow hammer.
cmcgregor (Forum Supporter) said:Ohhhhhh I wonder if it's the starter...
On the left, the bolt that was connecting the starter bracket to the block. On the right, a bolt that's actually short enough for the blind hole that the starter bracket goes into.
The last time I touched this was over a year ago, seems like it took a bit for the nut to shake it's way off the stud on the back of the starter and then the noise started.
Thanks for indulging my rambling, this has been bothering me for ages but apparently I just had to complain about it on the internet to actually be able to fix it!
Just what we need, proof that complaining on the internet actually fixes things :)
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