As with many things related to car maintenance, there are many different ways to perform an engine removal and install. Much of it comes down to preference, available tools, and work environment. Documented here are steps which have been found to work best specifically with the S14 motor in the BMW E30 M3. With the right tools and careful planning it can be a manageable and safe process. Due to the weight and size of the motor it is recommended to have someone available to assist but the process should still be possible alone. The key is to not rush and take your time, particularly with manipulating the loaded hoist/cherry picker. This guide describes removing the motor while leaving the transmission still attached as this avoids the often very difficult task of reaching the bolts on the top side of the bell housing.
Jack up and use jackstands or drive up on ramps or lift. The car should be high enough for you to be able to get completely under it.
The Guibo is the rubber junction piece which connects the driveshaft to the transmission. You must unbolt it by holding the backside nut with a wrench and removing the bolt. You only must remove the 3 bolts which connect the Guibo to the transmission (leave the 3 bolts which connect the driveshaft to the Guibo). These are torqued tight so it is recommended to use an impact wrench to remove these bolts.
It is recommended that you loosen the driveshaft clamp in the center which allows it to be slid back on splines. This will provide additional clearance between the driveshaft and transmission. You will need to use a pipe wrench to first loosen the clamp as shown, which will then allow the driveshaft to slide back. The driveshaft flex disk bracket can also be slid back a degree by loosening the 2 nuts which secure it to the frame.
Next you must unbolt the exhaust center section from the exhaust header. It is recommended that you remove the engine with the header still attached as the header flange nuts are hard to get to and prone to stripping. There are 6 bolts with nuts on the back side which must be held with a wrench. The top center bolt is difficult to get to and might require socket extenders and/or U-joint to accomplish. If the bolts are seized, it might help to use an impact wrench to remove them. Make sure in re-assembly to use anti-seize paste on the threads. Be careful not to lose the 2 exhaust header O-Rings when you separate the center section from the header as they can fall out.
The shift linkage must be uncliped from the shifter. With the driveshaft now disconnected and pulled back, it should be easier to reach up and unclip the shifter from the selector rod. You must also remove the 2 bolts which secure the support piece for the shifter and cup to the back of the transmission. Finally, make sure to unclip the reverse indicator wire which connects from inside the car to the transmission.
The hood must be removed. It is large and heavy so it is highly recommended that someone help with this task. First unclip the hood shock from the hood, taking care that the hood does not slam down. Next, remove the 2 outside screws on each side at the front of the hood which passes through the front flange. Then simply loosen the middle bolts which allow the hood to slide off the flanges. Dont forget to remove the grounding strap.
It is recommended that you drain the coolant before disconnecting the coolant hoses from the engine. On the E30 M3 the coolant drain plug on the bottom middle center of the radiator. At this time it is probably a good idea to completely remove the bottom front plastic cover as this will also help with the engine removal. The plastic undercarriage is secured by screws in the wheel well.
You will need to disconnect the coolant hoses from the engine. Using a flat head screw driver, loosen the hose clamp and then remove the hoses from the 2 front outlets on the coolant rail (on the exhaust side of the motor), from the connection between the water pump and the thermostat (just below the coolant rail), and from the back center of the cylinder head. If the hose to the back of the cylinder head (for the heater core) is too difficult to reach you can remove the side which leads into the firewall.
Remove the plastic engine fan shroud which is attached to the back side of the radiator via clips on either side. Next, use a very thin 32mm wrench (you can rent a fan clutch wrench set from Autozone or similar if needed) to remove the fan clutch from the water pump. You will need to hold the water pump to prevent it from spinning. Note that the fan clutch nut is reverse threaded, so you will feel like you are actually tightening the nut. Once the fan is removed pull it out along with the shroud.
You must remove the airbox and it is recommended that you also remove the intake plenum. To remove the airbox, simply disconnect the wires to the airflow meter, remove the rubber intake bellows and loosen the 2 nuts holding it to the bracket and pull up. To remove the intake plenum, it is recommended that you remove the nuts from the middle junction on the throttle bodies. remove the throttle cable bracket and disconnect the throttle cables from the throttle bodies. Disconnect the rubber hose on the underside of the plenum for the idle control valve. Finally, disconnect the plenum from its support bracket on the underside middle and it should pull away.
You must remove the AC compressor from the bracket attached to the engine block. The AC compressor is located on the lower front of the exhaust side of the motor. This is preferred so that you do not discharge your refrigerant. First, remove the bolts which connect the compressor to the curved metal bracket piece on top. This will allow you to rotate the compressor clockwise to remove tension on the belt. Then remove the belt from the pulleys. Next, remove the long lower bolt which connects the compressor to the bracket. Pull away the compressor from the engine block. It is recommended that you zip tie the compressor to the frame out of the way so that its weight does not damage the refrigerant lines.
You must disconnect the power steering lines from the power steering pump. It is easiest to do this where they connect to the pump, or alternatively you could disconnect them from the power steering rack. The power steering pump is on the front intake side of the engine, just below the alternator. You do not need to remove or adjust the pump itself.
You must disconnect the oil cooler lines from the oil filter bracket behind the alternator and below the intake plenum. The two lines connect to either side of the oil filter. Some oil may spill when removing the lines so be prepared to catch it.
First, disconnect the negative terminal from the battery in the trunk. Then, you need to disconnect the terminals from the back side of the alternator. Disconnect the temp and pressure sensors from the oil filter bracket. Disconnect the throttle position sensor at the front of the throttle bodies. Disconnect the connector to the idle control valve. Once the sensors are disconnected, pull away the wire harness from the underside of the throttle bodies. Next, disconnect the 3 sensors which pass up the drivers side of the transmission bell housing to the connectors against the firewall (note the color coded orientation). Remove the the wires connected to the starter and relay on the top side of the bell housing. Disconnect the O2 sensor which is mounted in the center of the exhaust header.
You must disconnect the fuel lines from the back of the fuel rail, which sits on top of the throttle bodies. Loosen the clamps and pull the hoses off. Take care to catch any fuel which might spill.
Now that the engine is disconnected you can attach the balance bar. There is a loop on the alternator bracket on the front of the engine, and at the rear on the block which you can attach to. Use of a balance bar is important as it will allow you to “shoe horn” the complete engine and transmission out of the car, as shown. Double check and make absolutely certain that the balance bar is securely mounted. Lift the hoist just enough so that the chains are taut.
Next, use the jack which you used to jack up the car to support the center of the transmission. Once the jack is in place and holding up the transmission, remove the nuts which hold the transmission cross brace to the frame. Do this very slowly and carefully to make sure that the jack is adequately supporting the transmission. Next, remove the 2 nuts which hold the rubber transmission mounts to the cross member. The cross member should then fall away, leaving the transmission supported fully by the jack.
With the hoist holding the top of the engine and the jack holding the transmission, remove the nuts which hold the motor mounts to the main cross member from under the car. Do this slowly to make sure the engine does not shift.
With the engine completely disconnected and supported by only the hoist and jack, begin very slowly bringing it up and out of the car. First, lift the hoist up slightly to pull the motor mount threads out from the cross member. Then bring the engine forward (allowing the jack to roll along with the transmission), taking care not to hit the water pump against the radiator. Next, lower the jack slightly, and then adjust the balance bar to tilt the engine upward. Keep repeating this process until the engine begins to lift out of the engine bay. You can remove the jack supporting the transmission once it is far enough out. It often helps during the last stages to either lower the front of the car or raise the rear to aid in lifting the engine out.