Mitsubishi Pick-ups and Montero 1983-1995 Repair Guide

Exhaust Manifold

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REMOVAL & INSTALLATION




CAUTION
Perform this operation only on a cold motor. The exhaust components and other metal parts will retain heat for a period of hours after the engine is shut off.

2.0L and 2.6L Engines

See Figures 1 through 5

Soak all the exhaust manifold retaining nuts and bolts with rust penetrant, if necessary, then tap the end of each one with a hammer and allow the penetrant to work for about 30 minutes for ease of removal.

  1. Disconnect the negative battery cable. Remove the air cleaner.
  2.  
  3. Disconnect the exhaust system component (pipe or catalytic converter) from the bottom of the exhaust manifold assembly. If access to this part is only from under the vehicle, safely raise and support the vehicle on jackstands.
  4.  
  5. Remove the air duct hose, the vacuum hose and the ground wire from the air pipe assembly reed valve. Remove the reed valve B bracket and the exhaust manifold cover.
  6.  



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Fig. Fig. 1: Exhaust manifold assembly components-2.6L Engines



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Fig. Fig. 2: Loosen and remove the bolts holding the exhaust manifold cover onto the manifold ...



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Fig. Fig. 3: ... then remove the exhaust manifold cover



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Fig. Fig. 4: Loosen and remove the attaching bolts



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Fig. Fig. 5: Remove the exhaust manifold with the air pipe assembly attached

  1. With the manifold cold, soak all the manifold nuts and studs with a liquid penetrant. The hardware will be difficult to loosen.
  2.  
  3. Disconnect and remove the oxygen sensor.
  4.  
  5. Suspend the manifold and remove all attaching nuts and washers. Pull the manifold off the head, if necessary rocking it to break it loose. Remove the exhaust manifold with the air pipe assembly and reed valve still attached.
  6.  

To install:
  1. Thoroughly clean the sealing surfaces on the cylinder head and manifold. Replace any nuts, washers, or studs that are excessively rusted or may have been damaged during removal. Studs may sometimes be removed by installing two nuts and twisting them in opposite directions to lock them, and then using your wrench on the inner nut, to remove the stud. Use a straightedge to check manifold and cylinder head sealing surfaces for flatness.
  2.  

Maximum acceptable warpage is 0.012 in. (0.3mm). Replace the the manifold assembly if necessary.

  1. Install new gaskets in such a way that all bolt holes and ports are lined up. Make sure all the nuts turn freely, oiling them lightly if necessary. Also make sure all the studs are screwed all the way into the block.
  2.  
  3. Place the manifold in position and support it while you install all the washers and nuts hand-tight.
  4.  
  5. Tighten the nuts and bolts alternately and in several stages to 12 ft. lbs. (16 Nm) working from the center position out.
  6.  
  7. Install the piping, heat stoves, shields and exhaust components. Always use new exhaust gaskets upon installation.
  8.  
  9. Operate the engine and check carefully for exhaust leaks.
  10.  

2.4L Engine

See Figure 6

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the exhaust manifold cover from the exhaust manifold.
  4.  
  5. Raise and safely support the vehicle to a medium height, so that the vehicle can be worked on from both the top and the bottom.
  6.  
  7. Disconnect the exhaust pipe from the manifold.
  8.  
  9. Disconnect the oxygen sensor connector and ground cable.
  10.  
  11. Remove the manifold mounting nuts and remove the manifold and gasket from the engine.
  12.  



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Fig. Fig. 6: Exhaust manifold assembly components-2.4L Engines

To install:
  1. Install the exhaust manifold, using a new exhaust manifold gasket, and tighten the mounting nuts to 13 ft. lbs. (18 Nm), starting from the middle and working outward.
  2.  
  3. Connect the oxygen sensor connector and ground cable.
  4.  
  5. Connect the exhaust pipe to the manifold. Lower the vehicle.
  6.  
  7. Install the heat cowl to the exhaust manifold.
  8.  
  9. Connect the negative battery cable.
  10.  
  11. Start the engine and check for exhaust leaks.
  12.  

3.0L (12 Valve) Engines

See Figure 7

LEFT MANIFOLD
  1. Disconnect the negative battery cable. Remove both the battery and the battery tray.
  2.  
  3. Remove the self-locking nuts holding both exhaust pipes to the manifolds. Remove the gaskets and discard them. Either hang the exhaust pipe from stiff wire or support it from underneath with wooden blocks.
  4.  
  5. Remove the heat shield from the manifold.
  6.  
  7. Remove the EGR pipe and its gaskets from the intake plenum and the exhaust manifold. The gaskets will need to be replaced with new ones.
  8.  
  9. Remove the front intake manifold plenum stay (support) and the bracket it is attached to.
  10.  
  11. Remove the retaining nuts and remove the exhaust manifold.
  12.  
  13. Remove the manifold gasket.
  14.  

To install:
  1. Inspect the manifold and head surfaces for cracks or distortion. Use a straightedge and feeler gauge to check the surfaces for warpage. Maximum acceptable warpage is 0.012 in. (0.3mm).
  2.  
  3. Place a new gasket against the head.
  4.  
  5. Install the manifold. Tighten all the nuts snug. In two passes and working from the inner nuts outward, tighten the retaining nuts to 11-16 ft. lbs. (15-22 Nm).
  6.  
  7. Reinstall the front intake manifold plenum stay and bracket.
  8.  
  9. Reattach the EGR pipe to the intake manifold plenum and the exhaust manifold using new gaskets.
  10.  
  11. Install the heat shield, tightening the bolts to 10 ft. lbs. (13 Nm).
  12.  
  13. Using new exhaust gaskets and new self-locking nuts, connect the exhaust system to both manifolds.
  14.  
  15. Reinstall the battery tray, then the battery. Reconnect the negative battery cable.
  16.  
  17. Start the engine and check for exhaust leaks.
  18.  



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Fig. Fig. 7: Exhaust manifold assembly components-3.0L (12 Valve) Engines

RIGHT MANIFOLD
  1. Disconnect the negative battery cable. Remove the air duct.
  2.  
  3. Remove the self-locking nuts holding both exhaust pipes to both manifolds. Remove the gaskets and discard them. Either hang the exhaust pipe from stiff wire or support it from underneath with wooden blocks.
  4.  
  5. Remove the heat shield, the rear engine hanger and the alternator stay from the exhaust manifold.
  6.  
  7. Remove the retaining nuts and remove the manifold and its gasket.
  8.  

To install:
  1. Inspect the manifold and head surfaces for cracks or distortion. Use a straightedge and feeler gauge to check the surfaces for warpage. Maximum acceptable warpage is 0.012 in. (0.3mm).
  2.  
  3. Install a new gasket and place the manifold in position. Tighten the all the nuts snug. In two passes and working from the inner nuts outward, tighten the retaining nuts to 11-16 ft. lbs. (15-22 Nm).
  4.  
  5. Install the alternator stay and tighten the upper bolt to 9-11 ft. lbs. (12-15 Nm) and the lower bolt to 11-16 ft. lbs. (15-22 Nm). Install the rear engine hanger. Install the heat shield, tightening the bolts to 10 ft. lbs. (14 Nm).
  6.  
  7. Using new gaskets and new self-locking nuts, connect the exhaust system.
  8.  
  9. Connect the negative battery cable and start the engine. Check for exhaust leaks.
  10.  

3.0L (24 Valve) and 3.5L Engines

See Figures 8 and 9

LEFT MANIFOLD
  1. Disconnect the negative battery cable. Remove both the battery and the battery tray.
  2.  
  3. Remove the self-locking nuts holding both exhaust pipes to the manifolds. Remove the gaskets and discard them. Either hang the exhaust pipe from stiff wire or support it from underneath with wooden blocks.
  4.  



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Fig. Fig. 8: Exhaust manifold assembly components-3.0L (24 Valve) Engines



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Fig. Fig. 9: Exhaust manifold assembly components-3.5L Engines

  1. Remove the heat shield from the manifold.
  2.  
  3. Remove the retaining nuts and remove the exhaust manifold.
  4.  
  5. Remove the manifold gasket.
  6.  

To install:
  1. Inspect the manifold and head surfaces for cracks or distortion. Use a straightedge and feeler gauge to check the surfaces for warpage. Maximum acceptable warpage is 0.012 in. (0.3mm).
  2.  
  3. Place a new gasket against the head.
  4.  
  5. Install the manifold. Tighten all the nuts snug. In two passes and working from the inner nuts outward, tighten the retaining nuts to 22 ft. lbs. (29 Nm) on both the 3.0L (24 valve) and 3.5L engines.
  6.  
  7. Install the heat shield, tightening the bolts to 10 ft. lbs. (14 Nm).
  8.  
  9. Using new exhaust gaskets and new self-locking nuts, connect the exhaust system to both manifolds.
  10.  
  11. Reinstall the battery tray, then the battery. Reconnect the negative battery cable.
  12.  
  13. Start the engine and check for exhaust leaks.
  14.  

RIGHT MANIFOLD
  1. Disconnect the negative battery cable. Remove the air duct and air cleaner cover.
  2.  
  3. Remove the self-locking nuts holding both exhaust pipes to both manifolds. Remove the gaskets and discard them. Either hang the exhaust pipe from stiff wire or support it from underneath with wooden blocks.
  4.  
  5. Only on the 3.5L engine remove the EGR pipe. Remove the heat shield from the manifold.
  6.  
  7. Remove the retaining nuts and remove the manifold and its gasket.
  8.  

To install:
  1. Inspect the manifold and head surfaces for cracks or distortion. Use a straightedge and feeler gauge to check the surfaces for warpage. Maximum acceptable warpage is 0.012 in. (0.3mm).
  2.  
  3. Install a new gasket and place the manifold in position. Tighten the all the nuts snug. In two passes and working from the inner nuts outward, tighten the retaining nuts to 14 ft. lbs. (19 Nm) on the 3.0L (12 valve) engine or to 22 ft. lbs. (29 Nm) on the 3.0L (24 valve) and 3.5L engines.
  4.  
  5. Install the EGR pipe and new gasket, if working on the 3.5L engine. Install the heat shield, tightening the bolts to 10 ft. lbs. (14 Nm).
  6.  
  7. Using new gaskets and new self-locking nuts, connect the exhaust system.
  8.  
  9. Connect the negative battery cable and start the engine. Check for exhaust leaks.
  10.  

 
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