LS400 1990-1997

Exhaust Manifold

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Precautions



Specific to:

Lexus LS400 1993-1996


CAUTION
On models with an air bag, wait at least 90 seconds from the time that the ignition switch is turned to the LOCK position and the battery is disconnected before performing any further work.

Removal & Installation



Specific to:

Lexus LS400 1993-1996

  1. Disconnect the negative battery cable. Drain the cooling system.
  2.  
  3. Remove the camshaft timing pulleys. Remove the cooling fan hydraulic pump on the SC400.
  4.  
  5. Disconnect the accelerator cable, the throttle control cable, if equipped with automatic transaxle and the cruise control actuator cable.
  6.  
  7. Remove the high tension cord cover and the right side ignition coil.
  8.  
  9. Remove the water inlet housing mounting bolts and disconnect the water bypass hose from the ISC valve.
  10.  
  11. Remove the water inlet and inlet housing assemblies. Remove the O-ring from the water inlet housing.
  12.  
  13. Remove the EGR pipe.
  14.  
  15. Disconnect the following:
    1. VSV connector
    2.  
    3. Vacuum pipe hose
    4.  
    5. EGR water bypass pipe
    6.  
    7. Fuel pressure VSV
    8.  

  16.  
  17. Disconnect the EGR vacuum hoses and remove the EGR VSV.
  18.  
  19. Disconnect the following hoses:
    1. Water bypass pipe hose from the ISC valve.
    2.  
    3. Water bypass joint hose.
    4.  
    5. Vacuum pipe hoses.
    6.  

  20.  
  21. Disconnect the EGR gas temperature sensor, California only. Remove the EGR valve adapter.
  22.  
  23. Disconnect the following:
    1. Fuel pressure regulator vacuum hose.
    2.  
    3. Air intake chamber vacuum hose.
    4.  
    5. Vacuum hose from the EVAP BVSV.
    6.  

  24.  
  25. Remove the mounting bolts, hoses and the vacuum pipe.
  26.  
  27. Remove the ISC valve.
  28.  
  29. Remove the throttle body sensor connectors and the water bypass pipe from the rear water bypass joint.
  30.  
  31. Disconnect the PCV valve hose. Remove the throttle body and gasket.
  32.  
  33. Disconnect the accelerator cable bracket and the brake booster vacuum union and hose.
  34.  
  35. Disconnect the cold start injector connector and the cold start injector tube from the right side delivery pipe, if equipped.
  36.  
  37. Disconnect the check connector from the intake chamber and remove the mounting nuts and bolts.
  38.  
  39. Remove the air intake chamber and the cold start injector, tube and wire assembly, if equipped.
  40.  
  41. Disconnect the engine wire from the intake manifold and from the right side cylinder head. Disconnect the heater hoses.
  42.  
  43. Remove the delivery pipes and the fuel injectors. Remove the mounting bolts and nuts. Lift up the intake manifold.
  44.  
  45. Remove the front and rear water bypass joint.
  46.  
  47. Raise and safely support the vehicle. Remove the front exhaust pipe and the main catalytic converters. Lower the vehicle.
  48.  
  49. Disconnect the right side oxygen sensor. Remove the mounting bolts and nuts and remove the right side exhaust manifold.
  50.  
  51. Remove the oil dipstick and guide. Disconnect the left side oxygen sensor.
  52.  
  53. Remove the mounting bolts and nuts and remove the left side exhaust manifold.
  54.  

To install:

  1. Install the right side exhaust manifold with a new gasket (the painted marks should face the manifold) and tighten the mounting bolts to 29 ft. lbs. (39 Nm). Connect the right side oxygen sensor connector.
  2.  
  3. Install the left side exhaust manifold with a new gasket (the painted marks should face the manifold) and tighten the mounting bolts to 29 ft. lbs. (39 Nm). Connect the left side oxygen sensor connector.
  4.  
  5. Install the oil dipstick and guide. Raise and safely support the vehicle.
  6.  
  7. Install the catalytic converters and front exhaust pipe. Lower the vehicle.
  8.  
  9. Install the front and rear water bypass joints. Tighten the mounting bolts to 13 ft. lbs. (18 Nm).
  10.  
  11. Install the intake manifold, using new gaskets. Tighten the mounting nuts and bolts to 13 ft. lbs. (18 Nm).
  12.  
  13. Install the delivery pipes and fuel injectors. Install the fuel return pipe with new gaskets. Tighten the union bolt to 26 ft. lbs. (35 Nm).
  14.  
  15. Connect the fuel hoses and the injector connectors. Connect the engine wire to the delivery pipes.
  16.  
  17. Connect the connectors on the left side delivery pipe, the water temperature sensor connector, cold start injector time switch connector and the water temperature sender gauge connector.
  18.  
  19. Connect the heater hoses and engine wire bracket. Install the engine wire to the bracket.
  20.  
  21. Install the cold start injector, tube and wire assembly. Tighten the mounting bolts to 69 inch lbs. (8 Nm), if equipped.
  22.  
  23. Install the air intake chamber with new gaskets and tighten the mounting bolts to 13 ft. lbs. (18 Nm).
  24.  
  25. Connect the cold start injector tube to the right side delivery pipe and tighten the union bolt to 11 ft. lbs. (15 Nm), if equipped.
  26.  
  27. Connect the cold start injector connector, if necessary. Install the accelerator cable bracket.
  28.  
  29. Install the brake booster union and connect the vacuum hose. Tighten the union bolt to 22 ft. lbs. (29 Nm).
  30.  
  31. Connect the water bypass hose to the throttle body and the PCV hose to the cylinder head cover.
  32.  
  33. Install the throttle body, using a new gasket. Tighten the mounting bolts to 13 ft. lbs. (18 Nm).
  34.  
  35. Install the water bypass pipe and connect the sensor connectors. Install the ISC valve and tighten the mounting bolts to 13 ft. lbs. (18 Nm). Connect the water bypass hose.
  36.  
  37. Install the vacuum pipe and the assorted hoses. Install the remaining components.
  38.  
  39. Connect and adjust the accelerator cable, the automatic transmission throttle cable and the cruise control actuator cable. Install the cooling fan hydraulic pump on the SC400. Install the camshaft timing pulleys.
  40.  
  41. Fill the cooling system and connect the negative battery cable. Start the engine and check for leaks.
  42.  
  43. Recheck all the fluid levels. Roadtest for proper operation.
  44.  

 
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