Mercedes Coupes/Sedans/Wagons 1974-1984 Repair Guide

Engine

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REMOVAL & INSTALLATION



In all cases, Mercedes-Benz engines and transmissions are removed as a unit.

190D, 190E, 230, 240D, 300D, 300CD, 300TD and 300SD Models See Figures 1, 2, 3 and 4

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Fig. Fig. 1: When removing the engine, use a wood-padded jack under the transmission to support the weight



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Fig. Fig. 2: To remove the engine, the battery cables must be disconnected



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Fig. Fig. 3: Loosen the air conditioning compressor retaining bolts ...



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Fig. Fig. 4: ... and move the compressor to one side without disconnecting the refrigerant lines

Remove the engine/transmission as a unit.

  1. Remove the hood, then drain the cooling system and disconnect the battery.
  2.  


CAUTION
When draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

  1. Remove the fan shroud, radiator, and disconnect all heater hoses and oil cooler lines. Plug all openings to keep out dirt.
  2.  
  3. Remove the air cleaner and all fuel, vacuum and oil hoses.
  4.  

Swing the A/C compressor aside. Leave lines connected. Disconnect all other fluid lines and hoses. Plug all openings to keep out dirt.

  1. Remove the viscous coupling and fan and disconnect the carburetor choke cable (if so equipped).
  2.  
  3. On diesel engines, disconnect the idle control and starting cables. On the 300SD, loosen the oil filter cover slightly. Siphon off the power steering fluid and disconnect the hoses.
  4.  
  5. On all engines, disconnect the accelerator linkage.
  6.  
  7. Disconnect all ground straps and electrical connections. Tag each wire for easy reassembly.
  8.  
  9. Detach the gearshift linkage and the exhaust pipes.
  10.  
  11. Loosen the steering relay arm and pull it down out of the way, along with the center steering rod and hydraulic steering damper.
  12.  
  13. The hydraulic engine shock absorber should be removed.
  14.  
  15. Remove the hydraulic line from the clutch housing and the oil line connectors from the automatic transmission.
  16.  
  17. Unbolt the clutch slave cylinder from the bellhousing after removing the return spring.
  18.  
  19. Remove the exhaust pipe bracket attached to the transmission and place a wood-padded jack under the bellhousing, or place a cable sling under the oil pan, to support the engine. On turbocharged models, disconnect the exhaust pipes at the turbo charger.
  20.  
  21. Mark the position of the rear engine support and unbolt the two outer bolts, then remove the top bolt at the transmission and pull the support out.
  22.  
  23. Disconnect the speedometer cable and the front driveshaft U-joint. Push the driveshaft back and wire it out of the way.
  24.  
  25. Unbolt the engine mounts on both sides and, on four-cylinder engines, the front limit stop.
  26.  
  27. Unbolt the power steering fluid reservoir and swing it out of the way; then, using a chain hoist and cable, lift the engine and transmission upward and outward. An angle of about 45- will allow the car to be pushed backward while the engine is coming up.
  28.  
  29. Reverse the procedure to install, making sure to bleed the hydraulic clutch, power steering, power brakes and fuel system.
  30.  

280, 280C, 280E, 280CE, 280SE & 280S MODELS



  1. Scribe alignment marks on the hood hinges and remove the hood. Drain the coolant from the radiator and block.
  2.  


CAUTION
When draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

  1. Remove the radiator.
  2.  
  3. Disconnect the lines from the vacuum pump.
  4.  
  5. On vehicles with air conditioning, remove the compressor and place it aside.
  6.  


CAUTION
Please refer to General Information And Maintenance before discharging the compressor or disconnecting air conditioning lines. Damage to the air conditioning system or personal injury could result. Consult your local laws concerning refrigerant discharge and recycling. In many areas it may be illegal for anyone but a certified technician to service the A/C system. Always use an approved recovery station when discharging the air conditioning.

  1. Disconnect and tag all electrical connections from the engine.
  2.  
  3. Disconnect all coolant and vacuum lines from the engine.
  4.  
  5. Disconnect and plug the pressure oil lines from the power steering pump, after draining the pump reservoir.
  6.  
  7. Remove the accelerator linkage control rod by pulling off the lock-ring and pushing the shaft in the direction of the firewall.
  8.  
  9. Loosen and remove the exhaust pipes from the manifold and transmission supports.
  10.  
  11. Disconnect the transmission linkage and all other connections.
  12.  
  13. Loosen the front right (driving direction) shock absorber from the front axle carrier.
  14.  
  15. Remove the left-hand engine shock absorber from the engine mount.
  16.  
  17. Attach a lifting device to the engine and tension the cables.
  18.  
  19. Unbolt the engine and transmission mounts and remove the engine at a 45- angle.
  20.  
  21. Installation is the reverse of removal. Be sure to check all fluids and fill or top up as necessary. Check all adjustments on the engine.
  22.  

V8 Engines

Removal of a V-8 engine equipped with air conditioning, requires disconnecting the air conditioning system.


CAUTION
Please refer to General Information And Maintenance before discharging the compressor or disconnecting air conditioning lines. Damage to the air conditioning system or personal injury could result. Consult your local laws concerning refrigerant discharge and recycling. In many areas it may be illegal for anyone but a certified technician to service the A/C system. Always use an approved recovery station when discharging the air conditioning.

  1. Remove the hood. On the 380 SEC, the hood can be tilted back 90- and does not need to be removed.
  2.  
  3. Drain the cooling system.
  4.  


CAUTION
When draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

  1. Remove the radiator and fan shroud.
  2.  
  3. Remove the cable plug from the temperature switch.
  4.  
  5. Remove the battery, battery frame and air filter.
  6.  
  7. Drain the power steering reservoir and windshield washer reservoir.
  8.  
  9. Disconnect and plug the high pressure and return lines on the power steering pump.
  10.  
  11. Detach the fuel lines from the fuel filter, pressure regulator, and pressure sensor.
  12.  
  13. If equipped, loosen the line to the supply and anti-freeze tanks. On models so equipped, disconnect the lines to the hydropneumatic suspension.
  14.  
  15. Disconnect the cables from the ignition coil and transistor ignition switchbox.
  16.  
  17. Disconnect the brake vacuum lines.
  18.  
  19. Detach the cable connections for the following:
    1. Venturi control unit
    2.  
    3. Temperature sensor
    4.  
    5. Distributor
    6.  
    7. Temperature switch
    8.  
    9. Cold starting valve
    10.  
    11. Speedometer inductance transmitter (380 series only)
    12.  

  20.  
  21. Remove the regulating shaft by pushing it in the direction of the firewall.
  22.  
  23. Disconnect the thrust and pullrods.
  24.  
  25. Disconnect the heater lines.
  26.  
  27. Detach the lines to the oil pressure and temperature gauges.
  28.  
  29. Remove the ground strap from the vehicle.
  30.  
  31. Detach the cables from the alternator, terminal bridge, and battery. Remove the battery.
  32.  
  33. On the 6.9, remove the oil line shield and disconnect the oil lines between the oil pan and oil reservoir.
  34.  
  35. Position a lifting sling on the engine and take up the slack in the chain.
  36.  
  37. Remove the left-hand engine mount and loosen the hex nut on the right-hand mount.
  38.  
  39. Remove the exhaust system. Remove the connecting rod chain on the rear level control valve and loosen the torsion bar slightly. Raise the vehicle slightly at the rear and remove the exhaust system in a rearward direction.
  40.  
  41. Disconnect the handbrake cable.
  42.  
  43. Remove the shield plate from the transmission tunnel.
  44.  
  45. Place a block of wood between the transmission and cross yoke so the engine will not sag, when the rear mount is removed.
  46.  
  47. Loosen the driveshaft intermediate bearing and the driveshaft slide.
  48.  
  49. Support the transmission with a jack.
  50.  
  51. Mark the installation of the crossmember and remove the crossmember. Remove the rear engine carrier with the engine mount.
  52.  
  53. Unbolt the front U-joint flange on the transmission and push it back. Do not loosen the clamp nut on the intermediate bearing. Support the driveshaft.
  54.  
  55. Disconnect the speedometer shaft, shift rod, control pressure rod, regulating linkage (on automatic transmissions), kickdown switch cable, starter lockout switch cable, and the cable for the back-up light switch.
  56.  
  57. Remove the front engine mounting bolt and remove the engine at approximately a 45- angle.
  58.  
  59. Installation is the reverse of removal. Lower the engine until it is behind the front axle carrier. Place a jack under the transmission and lower the engine into its compartment. While lowering the engine, install the right-hand shock mount.
  60.  

Fill the engine with all required fluids and start the engine. Check for leaks.

 
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