This topic contains 2 replies, has 2 voices, and was last updated by  MADdrifter 3 years, 2 months ago.

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  • #365

    Kavin Peterson
    Keymaster

    Does anybody know how to replace the alternator in Mazda Miata?

    #366

    Kavin Peterson
    Keymaster

    And is there any other alternators fit to the Miata?

    #399

    MADdrifter
    Participant

    Here is the proper insturction for NA-series Miata:

    Will take 30-45 mins. While the car can be driven for several hours without the alternator, the belt also runs the water pump, so you’ll need to get the part before hand.

    Tools required
    Ratchet or Air ratchet (preferred)
    10, 12 and 14mm sockets
    Phillips screw driver (optional)

    Notes:
    If any of your belts are more than 3-4 years old or are glazed, now is a good time to replace them. Recheck the tension after a month or 1,000 miles if replacing.

    1) First disconnect the battery. Otherwise you’ll do some impromptu arc welding and burn up who knows what.
    Then remove the plastic air intake by loosening the hose clamps on the throttle body and mass air sensor and one 14 mm bolt between the throttle body and engine block. Disconnect the vacuum line on the drivers side and the wire clamp on the passengers’ side. This should pull off pretty easily. A black seal with hose clamp can remain on the throttle body.

    2) Loosen the lower bolt. This goes through to the back and is held on with a nut. Mine was missing, so I don’t know the size. I’d guess 14 because mazda likes 10 and 14 mm.1 turn should be enough for now.
    Loosen the tensioning bolt (long 12 mm perpendicular to the alternator shaft), about 1/2 -3/4 inch, do not remove it.

    3) Remove the upper bolt (lock bolt) that connects the tensioning bolt to the alternator. The air ratchet is very good here because you can only move about 1/10th of a turn with a regular ratchet. The tensioning bolt will come off with it.

    4) Push the alternator in a clockwise motion to loosen the belt and slip it off the pulley.
    Remove the lower bolt. Hold onto the alternator when you pull out the bolt from the front.
    With all three bolts removed, rotate the alternator parallel to the crank shaft about 1/2 turn, disconnect the alternator plug (grayish color, two wires) and positive connection (single 10 gauge white wire). The positive connection may be under a two piece black dust cover.
    The alternator slips out the top passenger side between the throttle body and the radiator.
    To re-install, reverse.

    Specs:
    Alternator tension adjustment bolt (lock bolt) 14-19 lb-ft / 19-25 Nm

    Belt tension specs from 92 manual:
    New belt: 110-132 lb, 491-589 N , 50-60 kg
    Used belt: 110-132 lb, 422-491 N, 43-50 kg

    If you have a 90, or early 91, use a belt tension checker, it’s cheaper than a replacement block due to the crank shaft failure.

    • This reply was modified 3 years, 2 months ago by  MADdrifter.
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