So, over the past day or so my Miata has developed a curious noise, happens around 1800-2400rpm, largely not speed-dependent but I notice it a lot more in 1st, or if I'm cruising in 5th gear at 35-45. A few weeks ago I noticed my Beatrush undertray was vibrating a bit (no good mounting points for the rear pair of holes and I haven't set any rivnuts in the subframe to mount it by yet) between gears going up through the gearbox at reasonable speeds (read: not shifting at/near redline or WOT), all other mounting points are solid and tight however. This sound seems to have gotten slightly louder/deeper in tone in the past day or two, and I can feel more vibration through the body and the shifter as well. I'm also getting a strange (new) straining noise when turning the wheels at a stop or at backing-out-of-a-parking-spot speeds, although the steering effort hasn't noticably increased. is it possible the two are related? I haven't had the opportunity to get under the car and do any sort of diagnostic poking yet, until I can, spitball ideas?
if you made it this far through my disorganized rambling, congrats! composing anything useful on a little netbook sucks!
the steering sounds like air getting into the PS lines, or your PS pump is bad. I have that problem on cold mornings on the WRX (goes away once warmed up though). Kind of puts a load on the engine and makes a squealing noise.
As to the NVH, sounds like a bad motor or transmission mount.
Hmmmm. Sounds eerily reminiscent to the sounds I heard when my open rear diff was dying.
The problem when reversing sounds like a PS problem, but nothing else matches up. It may be a PS problem in combination with something else - maybe an out-of-balance wheel?
Harvey
HalfDork
2/6/15 10:14 a.m.
NA Miata means your motor mounts are probably shot to hell.
What year is your car? I have an early 1.6 car that came with the shortnose crank. It started getting much harsher NVH like you are describing when the front pulley started wobbling.
Type Q wrote:
What year is your car? I have an early 1.6 car that came with the shortnose crank. It started getting much harsher NVH like you are describing when the front pulley started wobbling.
From his profile, he has a 94
turboswede wrote:
Type Q wrote:
What year is your car? I have an early 1.6 car that came with the shortnose crank. It started getting much harsher NVH like you are describing when the front pulley started wobbling.
From his profile, he has a 94
My mistake. I looked at his profile but didn't click through to the detail on the car.
yeah, it's a '94 with roughly 115k miles on it. the noise presents when it's obnoxiously cold (as it was the past two days), and seems to spike when I turn the wheels when the car is stopped/moving slow enough to have to scrub the tires to get them to rotate, but doesn't matter whether I'm backing up or going forward. if it does turn out to be the PS pump going bad, what would the other symptoms be? I'll very likely just loop the PS lines on the rack and replace the pump with an idler if it's going bad, not much sense having PS on a car that has maybe 1150lbs on the front axle. the shot motor mounts accounting for more NVH wouldn't surprise me either, as far as I know they are the original ones.
