Miata Repairs
Every car over a year old needs either maintenance or repairs. This page will document the Miatas repairs as I do them hopefully helping someone in the process!
Repair 001: 3000rpm BBRRRzzzzzzTTT
The NA chassis miata has this fabulously loud and annoying buzz at around 3000rpms. They're caused by the aluminum heat shields on the stock exhaust. I pried and cut off all of the heat shields except the ones on the header, at the top of the catalytic converter, and the one over the top of the muffler. The buzz is 99% gone now and the car is beautifully silent. I had the Green Bean for four years, I can't believe that I never did this!
Repair 002: Airbag diagnostic control module
The week after I bought the Blueberry it rained from Tuesday until the next Saturday. It was torture looking out the window at my new convertible in the cold dreary downpour. I couldn't take it anymore on Saturday and decided to drive it anyway.
Lo and behold when I started it up the infamous blinking airbag light on the dash was there. It was the six blink code which is as you may have guessed the airbag diagnostic control module. It turns out that, over time, 5 of the capacitors on the circuit board begin to leak. The corrosion will short out in humid conditions throwing the airbag codes. If the blinking airbag light is left going without repairs to the system the diagnostic module self destructs via a fuse wrapped in a heating element. After that you get the 10 blink code and you have to buy another module. All of the 90-93 modules are the same and since it is a ford part you can get them out of various fords as well.
airbag diagnostic module is NA01-67-7F0A
back-up power supply module is NA01-67-7G0A.
The module and its battery (ie capacitor) are a pair of blue boxes directly over the drivers foot well. It takes some arm yoga to get it out despite only being held in by two 10mm nuts. To repair it you need the following:
- 5 100µF 35V DC capacitors
- a solder sucker or soldier wick to get the old soldier off of the board
- a nice soldering iron preferably with a long sharp tip
- solder
- some alcohol or circuit board cleaner
- q-tips
I highly suggest getting the capacitors from http://www.partsexpress.com/ or someplace online as the radio shack caps are low quality and severely overpriced. I bought the Radio Shack ones as I was pressed for time, at least they're not over 15 years old like the ones on the module!
If you aren't comfortable with this kind of work there are plenty of electronics places you could send or take the module to with the new capacitors. It turns out that J____ is good at such things and he did it at work for me for free, in the middle of a 12+ hour work day!
I plugged it back in and no airbag light, success! Be sure to clean the board gently but well!
Repair 003: Transmission fluid change
This is super easy so I won't really go into detail. All you need is a funnel with a roughly 3' tube on the end that you can feed through the back of the engine bay into the transmission fill hole. I used duct tape between the two and that didn't work very well. The drain plug is 24mm i believe and the fill plug is a square external type so i used an adjustable wrench.
I used Penzoil Syncromesh and it works better than whatever was in there and also better than the MT-90 that I had in the Green Bean. Very smooth. I used anti seize on the fill plug since that seized on the green bean and i couldn't get it out. This simple maintenance made a big difference and was well worth it.
Repair 004: Mazda Millennia oil filter
They're about an inch longer than the sad little lawn mower oil filters that Mazda wants you to use. It's still small but it's better than the other one!
Repair 005: All metal automatic transmission radiator
The tiny stock single row radiator was steaming and leaking like crazy after a week of driving it so I bought an all metal radiator for an automatic transmission (autopartswarehouse.com has the cheapest price on this). This radiator replaces the brackets that the stock radiator sit in, you just have to transfer over some threaded clips and two studs. It has extra coolant capacity too, which is nice insurance for track days, etc.
Installation:
- remove the belly pan. The stock bolts were pretty rusty so I went to lowes and replaced most of the bolts for the pan and the radiator itself with stainless bolts of the same size( M6x1.0x16 ) at least two nuts, 14 washers and around 12 -14 bolts.
- remove the lower bolts holding the fans and a/c lines.
- drain the coolant via the phillips head plastic plug in the bottom of the radiator then take the lower radiator hose loose.
- remove all of the upper bolts holding the radiator fans on and unplug both of the fans.
- Remove the two bolts holding the radiator brackets on at the sides.
- remove the upper radiator hose and the overflow tank hose.
- remove the passenger side radiator fan and move the drivers side one back some.
- remove the radiator and brackets.
- take the two studs from the radiator brackets off, they have tiny c clips holding them on. remove all of the threaded radiator fan clips.
- Install the two studs onto the new radiator along with the threaded fan clips.
- install radiator, fans, hoses and brackets.
- Fill with fresh coolant, start it up and check for leaks. Rejoice at having eliminated a common failure point!