Project Miata Update

Finally got a chance to work on the car a bit this past weekend. The custom AC hose worked out okay. Initially I was very pleased with the hose routing but when we attempted to fit the ITG filter we still had an interference due to the service port so we ended up with a final routing that is not as nice but gets the job done. We made use of existing body holes for securing rubber coated p-clamps and we made one custom bracket. We installed new o-rings and pulled a vacuum on the system that held at 29.9″ for 24 hours. AC should now be good to go once refilled with R134a.




Also got the new coolant return pipe fitted. Here we are mocking it up.




I greased up the Earl’s EZ-Beader to make the rolled bead in each end to keep the hose clamps secure. Even though aluminum is soft I think it is prudent to use a lubricant to lessen wear and tear on your tools and get a smoother finish. I then cleaned out the grease with rags and flushed with brake cleaner. Then I used a new Scotch-Brite pad to give it an even brushed finish. You don’t want to use old/dirty Scotch-Brite pads on aluminum as you can transfer contaminants that can cause corrosion.




Here’s the engine bay with AC and coolant return pipe fitted. We shortened the two hoses between the rear water outlet/ inline thermostat housing and between inline thermostat housing/ coolant return hard pipe. Initially I used a cut up OEM rubber NB lower radiator hose for the connection between the coolant return hard pipe and upper radiator neck but it fit way too loose. I did some quick ruick research online and it seems that many preformed rubber hoses fit tighter at the ends than they do in the middle so they aren’t the greatest for hacking up for custom applications like this. I ended up using a section of the long silicone hose provided with the M-tuned reroute kit. Even then I really had to crank down in the hose clamp to tighten it. Fingers crossed there are no coolant leaks. That being said, my new flexible hose clamp driver is a life saver for getting to those hose clamps at the rear water outlet and a bargain at only $10. Time will tell if we will need additional support for the coolant return hard pipe once it’s filled with water. But right now it doesn’t rub against anything and goes exactly where we need it to go.




Next up: 1) make bracket to offset lower NA6 coolant hard pipe for radiator hose clearance around the sway bar and exhaust manifold to the mixing manifold. 2) cut new ITG air filter backing plate to place air filter in final location. 3) make custom fuel hoses. 4) wire up all sensors and finish Megasquirt and WB02 installation.

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