1991 Miata Maintenance Notes
Notes for the 1999 Automatic.
I suppose I could consolidate my whole maintenance record here, I used to keep
it in a little paper notebook, then I transferred it to a Palm Pilot - it still
lives in the Palm Desktop that just got migrated to our new
PC, but I wonder how long before that
gets hopelessly lost... so, webpages have proven pretty durable...
September 4, 2022, 115058 miles
New Seat Covers
June 6, 2021, 114540 miles
Fuel pump replaced.
December 10, 2020 through May 7, 2021, 114422 miles
Rocketeer V6 installed.
January 11, 2020
Coolant flush 50/50 Prestone Concentrate & Target purified water,
just a little red came out. Also, the drain plug cracked, replaced with
a NEEDA 611233 M12-1.25 which had to have the threaded section trimmed
shorter to fit. Even though it's easy to cross-thread like that, still
like it better than the original hex-head plug which had too little
plastic backing up the rubber washer.
New battery a few weeks before - not driving enough lately to keep it charged.
November 24, 2018, 114248 miles
Coolant flush, 50/50 Prestone & WalMart Distilled water.
Had been running clear, but a month or two ago turned red again.
March 5, 2017, 113328 miles
Thermostat replacement with 180 degree Stant.
March 2, 2017, 113300 miles
Coolant flush, replace with 50/50 Prestone & Publix Purified water.
Still a little red, also removed some sediment from overflow tank, but not much.
Thermostat has been sticky, not opening soon enough when driving constant
low RPMs after startup - have replacement, not yet installed.
A few days ago had the exhaust downpipe replaced and weld to the muffler repaired.
Replacement wastegate exit pipe was useless, too much bending of the coolant return
hardpipe required to use it, kept original exit pipes - shop repaired with re-weld
to the flange.
February 28, 2016, 112962 miles
Coolant flush, replace with 50/50 Prestone & Publix Purified Water.
Much less red this time, but still some red coming out when block drained.
September 12-23, 2015, 112090 miles
September 8, 2015, 112090 miles
- new NGK Long Reach Heat Range 6 plugs, gapped to 0.025"
Existing plugs were same brand and type looked fair and even, gaps read 0.035 to 0.037. New plugs were factory gapped at 0.040,
gaps adjusted by the "knock on wood" method.
September 5, 2015
August 30, 2015, 112033 miles
- 15w50 (Mobil1) Oil and Fram filter
- Like the "grippy top" on the Fram filter a lot
- Checked drain plug magnet, some schmutz on it, but no shiny stuff or things you can feel between your fingers.
- New copper crush washer (plug came with plastic, ick)
- Coolant flush and replace
- Cleaned overflow tank
- New 13psi radiator cap
August 23, 2015
- Windshield washer nozzles replaced with Mazda Tribute units
- Nice wide spray pattern, but a bit of spray coming over top of windshield when stopped
- Hose replaced with 3/16 I.D. 1/4 O.D. soft (Shore 70A) clear hose from McMaster
- Y coupling in washer hose replaced (original had big hole)
- Hood prop rod latch replaced
- First seat covers ever installed.
July 1, 2012, 105140 miles
- 20w50 Oil and filter
- New drain plug with magnet
January 1, 2012, 103500 miles
- Timing Belt
- Alternator belt and A/C belt
- Water Pump
- Thermostat
February 2010, 95440 miles - catching up:
- Oil and filter today
- Horn - air trumpets finally gave it up, installed single electric unit in January 2010
- Radiator and most minor hoses, installed in December 2009, battery ran pretty flat waiting
for this repair, seemed to recover well after a charge.
All in November 2008, between 90800 and 90880 miles, in no particular order:
- Battery - Big crank ETX30L,
replaced a 4 year old liquid filled Bosch that was getting just a little too weak in the cold - note
about the liquid filled battery, when overfilled it vented out the tube during charging, just like it
was supposed to, but the tube vent on the 1991 cars drips directly on the exhaust pipe, probably a
good idea to watch for that and rinse it off when first running just after filling with water.
- Outboard heater hose, firewall gromet and the metal pipe and O-ring that run up to the thermostat.
The pipe developed a hole where a mod-bend was exposed to exhaust manifold heat - not complaining
really, this is 10+ years after the mod-bend was made. New pipe also had to be bent to clear the
turbine exit downpipe, but this time it is a new pipe instead of already 6+ years old. Didn't change
the inboard heater hose because the hoses were actually in excellent shape (and the engine side
clamp looks to be a real problem to work on.) Notes on the job: dish soap is an excellent lubricant,
and necessary for sliding the spring clamps around / putting in the new gromet, etc. Also, the
firewall penetration pipes are made of thin soft copper, the old hose should be cut off lengthways
with a sharp knife, pulling is futile. Also did a full coolant system flush with this job, but kept
the existing thermostat and radiator cap, cap might be ready for replacement soon, thermostat seems
to be working well.
- Oil and filter - it was time.
- Spark plugs and wires - need to get the plug part number here, I believe they are NGK long reach heat
range 6? Wires are Magnacore 8.5mm - the old wires were letting spark arc past the plug insulator
during boost, causing stumbling. Old plugs had a gap reading of about .037, gapped the new plugs to
.025.
Last updated May 2021
