Saturday, March 22, 2014

How to Change a 1999 Miata Exhaust Manifold

Mazda completely redesigned the Miata for the 1999 model year with a completely different look. Many enthusiasts were relieved that Mazda left well-enough alone underneath. The 1999 Miata still used the same 1.8 liter four-cylinder engine that was used in the first-generation cars. The stock single-exhaust pipe is attached to a cast-iron exhaust manifold that is bolted to the engine. A cracked manifold will allow exhaust gases to enter the passenger compartment and should be replaced immediately.

Instructions

    1

    Spray penetrating fluid on the heat shield retaining bolts, the exhaust manifold-to-engine block bolts, the EGR pipe fitting and the exhaust pipe-to-manifold bolts. Allow the fluid to soak in overnight, if possible.

    2

    Loosen and remove the nut and bolt that secures the factory shock tower brace to the drivers side shock tower with a socket and ratchet. Lift the brace straight up to allow access to the exhaust manifold. Skip this step if your car did not come equipped with the shock tower brace.

    3

    Loosen and remove the retaining bolts for the windshield washer reservoir with a socket and ratchet. Lift the tank straight up and move it to the side -- as far as the connections will allow -- to provide access to the heat shields on the exhaust manifold. Skip this step if your car is not equipped with anti-lock brakes.

    4

    Loosen and remove the retaining bolts on the air cleaner housing on top of the engine with a socket and ratchet. Loosen the clamp that secures the air intake hose to the air cleaner housing with a Phillips screwdriver. Pull the hose off the housing. Push the housing to the side to allow access to the heat shields and exhaust manifold. Cover the ends of the intake hose and its fitting on the air cleaner housing with clean rags to prevent foreign debris or dirt from entering.

    5

    Loosen and remove the retaining bolts that attach both of the heat shields to the exhaust manifold with a socket and ratchet. Remove the heat shields from the manifold and place them aside.

    6

    Remove the EGR tube retaining bolts on the exhaust manifold and the intake manifold with a socket and ratchet. Loosen and unscrew the fitting that attaches the EGR tube to the end of the exhaust manifold with a tubing wrench.

    7

    Loosen and remove the three bolts that attach the exhaust pipe to the exhaust manifold with a wrench.

    8

    Loosen and remove the exhaust manifold-to-engine block retaining bolts with a socket and ratchet. Work slowly to avoid damaging or breaking off the bolts in the block. Stop and apply more penetrating fluid, if one or more of the bolts seem very tight. Allow the fluid to soak in for several hours, if possible.

    9

    Pull the manifold away from the engine block. Note that the water pipe bracket will slide off one of the manifold mounting studs as you remove the manifold. Do not allow the water pipe to move rearward. Remove the manifold from the engine bay. Remove the exhaust manifold gasket from the engine block. Scrape away any gasket residue on the mounting surface with a gasket scraper.

    10

    Position a new exhaust manifold gasket over the mounting studs on the engine block. Position the replacement exhaust manifold over the mounting studs. Push the water pipe bracket over the stud that it was originally attached to. Replace and tighten the manifold retaining bolts to between 29 and 33 foot-pounds with a torque wrench.

    11

    Replace the exhaust pipe-to-manifold bolts and tighten them to between 32 to 44 foot-pounds. Tighten the EGR tube fitting into the end of the manifold to between 24 and 34 foot-pounds. Replace and tighten the remaining EGR tube retaining bolts.

    12

    Replace the heat shields and tighten the retaining bolts. Place the air cleaner housing into position and tighten the retaining bolts. Remove the rags from the intake hose and air cleaner housing. Push the intake hose onto the housing and tighten the hose clamp.

    13

    Replace the windshield washer reservoir -- if your car has ABS -- and tighten the retaining bolts. Push the shock tower brace -- if your car is so equipped -- into position and replace and tighten the retaining bolt and nut.

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