Exhaust pipe/flange detached from the motor on a 96 Cavalier 2.4L twin cam engine. Does the flange and exhaust come as one part or if not rusted out can I re-attach myself ? Mike in MI

go to a junkyard ther is a good place to look

you can not just change the engine you would need to change the transmission and the computer the front exhaust pipe but if you are willing do do it anyway the signal cam engines had a problem with the cylinder heads cracking and the dual cam is common for oil leaks

Check this procedure, according with the repair guide for...

2.3L and 2.4L Engines
(see Figure 9)

1. Disconnect the negative battery cable
   
2. Detach the oxygen sensor connector.
   
3. Properly drain the engine coolant into a suitable container. Remove the heater hose from the thermostat housing for more complete coolant drain.
   
4. Remove upper exhaust manifold heat shield.
   
5. Remove the bolt that attaches the exhaust manifold brace to the manifold.
   
6. Remove the lower exhaust manifold heat shield.
   
7. Break loose the manifold to exhaust pipe spring loaded bolts using a 13mm box wrench.
   
8. Raise and safely support the vehicle.
   

It is necessary to relieve the spring pressure from 1 bolt prior to removing the second bolt. If the spring pressure is not relieved, it will cause the exhaust pipe to twist and bind up the bolt as it is removed.

1. Unfasten the two radiator outlet pipe-to-water pump cover bolts.
   
2. Remove the manifold to exhaust pipe bolts from the exhaust pipe flange as follows:
   1. Unscrew either bolt clockwise 4 turns.
      
   2. Remove the other bolt.
      
   3. Remove the first bolt.
      

On the 2.4L engines, DO NOT rotate the flex coupling more than 4° or damage may occur.Pull down and back on the exhaust pipe to disengage it from the exhaust manifold bolts.

1. Remove the radiator outlet pipe from the oil pan and transaxle. If equipped with a manual transaxle, remove the exhaust manifold brace. Leave the lower radiator hose attached and pull down on the outlet pipe to remove it from the water pump. Leave the radiator outlet pipe hang.
   
2. Carefully lower the vehicle.
   
3. Unfasten the exhaust manifold-to-cylinder head retaining nuts, then remove the exhaust manifold, seals and gaskets.
   
4. For the 2.4L engine, remove the front timing chain cover and the chain tensioner. For details, please refer to the procedure located later in this section.
   
5. Unfasten the water pump-to-cylinder block bolts. Remove the water pump-to-timing chain housing nuts. Remove the water pump and cover mounting bolts and nuts. Remove the water pump and cover as an assembly, then separate the two pieces.

Fig. 9: Water pump and cover mounting - 2.3L and 2.4L engines (click over image for zoom)

To install:

1. Thoroughly clean and dry all mounting surfaces, bolts and bolt holes. Using a new gasket, install the water pump to the cover and tighten the bolts finger-tight.
   
2. Lubricate the splines of the water pump with clean grease and install the assembly to the engine using new gaskets. Install the mounting bolts and nuts finger-tight.
   
3. Lubricate the radiator outlet pipe O-ring with antifreeze and slid the pipe onto the water pump cover. Install the bolts finger-tight.
   
4. With all gaps closed, tighten the bolts, in the following sequence, to the proper values:
   1. Pump assembly-to-chain housing nuts-19 ft. lbs. (26 Nm).
      
   2. Pump cover-to-pump assembly-106 inch lbs. (12 Nm).
      
   3. Cover-to-block, bottom bolt first-19 ft. lbs. (26 Nm).
      
   4. Radiator outlet pipe assembly-to-pump cover-125 inch lbs. (14 Nm).
5. Using new gaskets, install the exhaust manifold. Make sure to following the tightening sequence and torque specifications given in the exhaust manifold procedure located in this section.
   
6. Raise and safely support the vehicle.
   
7. Index the exhaust manifold bolts into the exhaust pipe flange.
   
8. Connect the exhaust pipe to the manifold. Install the exhaust pipe flange bolts evenly and gradually to avoid binding. Turn the bolts in until fully seated.
   
9. Connect the radiator outlet pipe to the transaxle and oil pan. Install the exhaust manifold brace, if removed.
   
10. On the 2.4L engine, install the timing chain tensioner and front cover.
    
11. Install the lower heat shield.
    
12. Carefully lower the vehicle.
    
13. Fasten the bolt that attaches the exhaust manifold brace to the manifold.
    
14. Tighten the manifold-to-exhaust pipe nuts to specification.
    
15. Install the upper heat shield.
    
16. Attach the oxygen sensor connector.
    
17. Fill the radiator with coolant until it comes out the heater hose outlet at the thermostat housing. Then connect the heater hose. Leave the radiator cap off.
    
18. Connect the negative battery cable, then start the engine. Run the vehicle until the thermostat opens, fill the radiator and recovery tank to their proper levels, then turn the engine off.
    
19. Once the vehicle has cooled, recheck the coolant level.

Hope helps; remember to rating this answer and leave a testimonial comment. Thank you for using FixYa.

There is a bracket that attaches the exhaust pipe to the engine block. Remove the 2 screws that hold
that bracket on. I think they are 12mm heads. Detach the 2 exhaust manifold to exhaust pipe screws,
the screws have 15mm heads. A 15mm deep socket is best. After you remove those 2 15mm screws you can pull the exhaust pipe down, remove the old exhaust flange and put the new one on.

Rettach the exhaust manifold to pipe screws, and reattach the bracket and youre done.

The Oxygen Sensor is located: Under hood, center, front engine area, above exhaust pipe flange, mounted in exhaust manifold
Application: Front

Under hood, center, rear engine area, above exhaust pipe flange, mounted in exhaust manifold
Application: Rear

I hope helps (remember to rate this). Good luck.

Under hood, center, front engine area, above exhaust pipe flange, mounted in exhaust manifold
Application:
Front
Under hood, center, rear engine area, above exhaust pipe flange, mounted in exhaust manifold
Application:
Rear

The oxygen sensor may be difficult to remove when the engine temperature is below 120°F (48°C). Excessive force may damage the threads in the exhaust manifold of exhaust pipe.

1. Start the engine and let it warm up to 120°F (48°C), stop the engine and disconnect the negative battery cable.
2. Detach the electrical connector from the oxygen sensor.
3. Using a special, oxygen sensor socket, remove the oxygen sensor from the exhaust manifold or exhaust pipe.

NOTE A special anti-seize compound is used on the oxygen sensor threads. The compound consists of liquid graphite and glass beads. The graphite will burn away, but the glass beads will remain, making the sensor easier to remove. New or service sensors will already have the compound applied to the threads. If an oxygen sensor is removed from the engine and if for any reason, it is to be reinstalled, the threads must have this anti-seize compound applied before installation.

1. Coat the threads of the oxygen sensor with anti-seize compound 5613695 or equivalent.
2. Install the sensor and tighten it to 30 ft. lbs. (40 Nm).
3. Reattach the electrical connector to the sensor and the negative battery cable.

Fig. Location of the rear O2 sensor


Fig. Location of the the front O2 sensor


Fig. Use a wrench or special socket to loosen the O2 sensor


Fig. When replacing or reinstalling an oxygen sensor, be sure to lube the threads sufficiently

It will work as long as you have the ECM to match the Motors. The regular 2.2 has a different engine management system then the 2.4 so the engine will fit but the ECM needs to understand the engine.
Good luck and hope this helps.

Yes you can if you also change the ECM for a 2.2 liter engine.
The ECM for the 2.4 liter engine have different programing then the 2.2 liter.
Good luck and hope this helps. 
ECM stands for "Engine Control Module" and is the generic term for the computer that controls engine functions. On some models, this same computer also controls the transmission, and is referred to as the "PCM" or "Powertrain Control Module". 

If the flange has rotted off the pipe, I know that there is a company that makes a hinged flange replacement.(check your local parts house for availability) If the flange is still good and the flair on the pipe is damaged you need to change the pipe. If flared on both ends or if anything is welded to the pipe, flange comes with the pipe.

I just changed a 2.4 in my 96. I pulled the whole thing because I coudn't get at the converter to flywheel bolts. After reading further, I saw information to pull the trans out through the drivers wheel well without the engine. They removed the starter to access the flywheel bolts to the converter.
I haven't tried it but it would make sense and it does make it a lot easier. Without the trans attached, you wouldn't need to remove the master cylinder or beat the sh-t out of the battery tray to get the think out.