M104.98x Motor Swap in a 190E

One of the most common engine swaps for a 190E is the installation of the bigger M103 3.0L motor. The swap from the smaller 2.6L M103 to a 3.0L M103 is a direct bolt-on swap (assuming the engines from the same cutoff years are used) and gives a small increase of around 30HP. Another option is to swap in the CIS version of the M104 engine found on the earliest M104 powered cars (1990-1992 300CE and 1990-1993 300SL). The injection system is still CIS and the ignition system is still EZL, but additional work is required to make the swap complete.

1. Disconnect battery
2. Remove front bumper
3. Remove air filter
4. Remove upper radiator support
5. Vacuum lines
   1. EGR, 2 lines
   2. Smog pump
   3. EZL
   4. Check valve at driver fender
   5. Two at the rear of intake manifold
   6. Black striped white vacuum line for throttle body
   7. Brake booster line
6. Cooling System
   1. Drain and remove radiator
   2. Disconnect water heater lines
      1. Supply at passenger fender
      2. Return at rear lifting hook
   3. Remove overflow pipe to coolant reservoir
7. AC System
   1. Vacuum AC system and remove condenser
      1. Wiring under both headlights and loom ties
      2. Bolt on driver side securing pipe to chassis
   2. Disconnect AC hose on driver fender
8. Power steering
   1. Siphon/extract power steering fluid
   2. Disconnect supply and return lines on pump
9. Disconnect fuel lines
   1. Supply at fuel distributor, 2x 17mm
   2. Return behind ignition coil, 17mm and 14mm
10. Disconnect throttle cables
11. Disconnect main engine wiring and set aside
    1. 4 prong CIS
12. 1 prong temperature sensor
13. 2 prong temperature sensor
    1. Cold start valve
    2. EHA
    3. Idle microswitch
    4. Airflow potentiometer
    5. IACV
    6. AC compressor
    7. Throttle position switch
    8. Ground wire at intake
    9. 2 plugs at the EZL
14. Disconnect auxiliary wiring and set aside
    1. Oil level sensor
    2. Oil pressure sensor
    3. Starter
    4. 10mm bolt at rear of intake manifold
15. Other wires
    1. Cruise control servo (8 pin connector under ABS pump)
    2. Disconnect alternator
    3. Crankshaft position sensor (rear) at EZL
    4. Crankshaft position sensor (front) underneath X92
    5. Ignition coil
16. Disconnect exhaust downpipes from exhaust manifold
17. Transmission
    1. Remove transmission mount
    2. Disconnect driveshaft from flex joint
    3. Disconnect transmission shifter linkage(s)
       1. Suggest removing entirely to avoid bending the rods accidentally
    4. Disconnect transmission slave cylinder fluid line (manuals only)
    5. Unbolt ground from bell housing
    6. Disconnect speedometer cable
18. Unbolt engine mounts from chassis
19. Secure engine to hoist and lift to remove. Remove with transmission attached.