Exhaust Manifold (Thermal Reactor)

REMOVAL & INSTALLATION

Carbureted Engine

NOTE: 1979–80 RX-7 models use a thermal reactor, instead of a traditional or reactive exhaust manifold.

1. Remove the air cleaner assembly and hot air duct hose. Remove the air injection pump.
2. If so equipped, disconnect the thermal reactor-to-air control valve air pipe.
3. Remove the intake manifold/thermal reactor upper side nuts. Mazda makes a special angled T-bar wrench for this job (tool number 49–8501–125 or equivalent).
4. Raise the vehicle and safely support it on jackstands. Disconnect the air pipe, running between the inlet manifold and the heat exchanger, from the inlet manifold.
5. If applicable, remove the air pipe running between the thermal reactor and the air duct.
6. If applicable, unfasten the air duct hanger bracket from the transmission housing, and disconnect the air duct from the thermal reactor.
7. Remove the intake manifold/thermal reactor lower side nuts.
8. Remove the intake manifold/thermal reactor and gasket. Thoroughly clean the gasket mating surfaces.

   To install:

9. Position a new gasket and install the intake manifold/thermal reactor. Attach the lower side mounting nuts and tighten them in several stages to 33–40 ft. lbs. (45–54 Nm).
10. If applicable, connect the air duct, then fasten its hanger bracket to the transmission housing.
11. If applicable, install the air pipe between the thermal reactor and the air duct.
12. Connect the air pipe from the heat exchanger at the inlet manifold.
13. Lower the vehicle.
14. Attach the upper side mounting nuts and tighten them in several stages to 33–40 ft. lbs. (45–54 Nm).
15. If applicable, connect the air pipe between the thermal reactor and air control valve.
16. Install the air injection pump.
17. Install the air cleaner assembly. Be sure to connect the hot air duct hose.

Fuel Injected Engine

NON-TURBO

1. Disconnect the negative battery cable.
2. Remove the air intake manifold (throttle and dynamic chamber), as described earlier in this section.
3. Unfasten the screws and nuts that attach the exhaust absorber plate to the exhaust manifold insulator, then remove the plate.

   Fig. 1: Exhaust manifold assembly — fuel injected non-turbo engine

4. Detach the oxygen sensor connector, then route the wiring so that it can be readily removed with the exhaust manifold.
5. Raise and safely support the front end on jackstands. Remove the exhaust pipe front cover, catalytic converter cover and exhaust pipe bracket. Disconnect the exhaust pipe from the exhaust manifold.
6. Loosen and remove the exhaust manifold retaining nuts and lockwashers.
7. Separate the manifold and insulator from the engine, then pull the manifold from the engine mounting studs. Remove the gasket and discard it.
8. Thoroughly clean the exhaust manifold contact surfaces, then check the exhaust manifold for warpage using a metal straightedge.

   To install:

9. Position a new manifold gasket on the engine. Install the exhaust manifold assembly over the mounting studs, flush with the gasket. Install the lockwashers and mounting nuts, then torque to 23–34 ft. lbs. (31–46 Nm).
10. Connect all the exhaust manifold components, using new gaskets as required.
11. Attach the oxygen sensor connector. Install the exhaust absorber plate, and torque the retaining screws to 6–8 ft. lbs. (8–11 Nm).
12. Install the air intake manifold, as described earlier in this section.
13. Connect the negative battery cable.
14. Start the engine and allow it to reach normal operating temperature, then check for exhaust leaks.

TURBO

1. Disconnect the negative battery cable. Drain the cooling system.
2. Disconnect the hoses from the air pump, then remove the air pump from the engine.
3. Loosen the hose clamps, then disconnect the funnel and air hose from the air cleaner and turbocharger. Remove the air funnel and air hose from the engine.
4. Detach the connector from the air control valve and remove the valve from the engine.
5. Disconnect the split air pipe from the engine and remove the pipe, along with the gasket.
6. Disconnect and remove the water hose and water pipe from the engine.
7. Disconnect the supply and return oil pipes from the turbocharger. (There may be some oil left in the lines, so be prepared to collect any residual oil with a small plastic container. Be sure to cover the openings to protect the system.)
8. Remove the front catalytic converter insulator covers, then disconnect the front converter from the turbocharger. Remove and discard the old gasket.
9. Unstake the retainer tabs from the retainer plate with a small prying tool. Remove the nuts and washers that secure the turbocharger to the exhaust manifold studs, then remove the turbocharger from the engine. Immediately cover all the turbo openings to prevent the entry of dirt and foreign matter. Remove the turbocharger gasket and purchase a new one.
10. Remove the insulator covers from the exhaust manifold. Loosen and remove the exhaust manifold retaining nuts/lockwashers.
11. Remove the exhaust manifold and waste gate actuator assembly from the engine. Remove the gasket and discard it.
12. Thoroughly clean the exhaust manifold and turbocharger contact surfaces, then check the exhaust manifold for warpage with a metal straightedge.

    To install:

13. Place a new manifold gasket on the engine. Install the exhaust manifold/actuator assembly over the mounting studs and position it flush with the gasket. Install the lockwashers and mounting nuts, then torque them to 23–34 ft. lbs. (31–46 Nm).
14. Install a new turbocharger gasket onto the exhaust manifold, then carefully guide the turbo assembly over the mounting studs and onto the gasket. Install the lockwashers and mounting nuts, and torque them to 33–40 ft. lbs. (45–54 Nm). Once the nuts are torqued, crimp the tabs on the nut retaining plate to prevent the nuts from loosening. Remove the protective covers from the turbo openings.
15. Connect the front converter to the turbocharger with a new gasket. Torque the nuts to 33–40 ft. lbs. (45–54 Nm).
16. Install the remaining components in reverse of their removal procedure. Install a new gasket for any part requiring one:
    • Insulator covers
    • Oil pipes
    • Water pipe and water hose
    • Split air pipe
    • Air control valve
    • Air funnel and air hose
    • Air pump and air hoses
17. Fill the cooling system to the proper level with a suitable coolant mixture and connect the negative battery cable.
18. Start the engine and check for leaks. Make all necessary adjustments.