Saturday, September 29, 2018

Miata NA cursed water plug part # FEA7-13-104


1991 Miata US w/ 226K miles

Overall the job was straight forward and took me a couple of hours with breaks.

Only needed to remove the ignition coil which turns out to have been the hardest part. Specifically the lower bolt [12mm].  Removing two heater hoses would have made it easier. I did not.

Special thanks to Rocky's Miatomotive for advice on access


- ratchet/12 mm socket
- regular pair of pliers
- small flashlight
- flat head screw driver

- FEA7-13-104 (cap, ceiling)
- Clamp (worm style)


- While I could reach in with my left hand from the passenger side and touch the plug, I needed visibility and additional access in order to remove and replace the clamp.  Removing the ignition coil served two purposes

1) allowed me to shine a flashlight down onto the plug so I could see to grip the clamp
2) provided access to allow me to tighten the new clamp (used worm gear)


Step 1 - remove ignition coil.  top 2 12mm bolts are easy.  bottom 12mm bolt was a challenge due to limited room.  I was able to get a ratchet on the bolt and it was slow going.  Range of motion was limited by the heater hoses so only turning the bolt about a 16th turn each time.

Step 2 - remove clamp/cap.  with a flashlight shining down from the space opened up after removing the coil, with my left hand I was able to get a pair of pliers on the clamp and the light allowed me to see what I was doing.  Clamp/cap came of easily with no residue on the pipe.

Step 3 - replace cap/clamp.  using my left hand I was able to reach in a and push on the cap.  used saliva as lubricant.  then used my left hand to slip on the clamp and hold it in place.  Then looking down from on top [ignition coil gap] , with my right hand was able to use a screw driver to tighten the worm clamp.

Step 4 - replace ignition coil.  Tight fit but was able to get the bolt started then, as above, took a while to tighten due to limited range of motion on the ratchet.