After my previous engine became thirsty for oil, I decided to install an M50B25 that I had setting in my garage. I had bought it the year before without a particular plan for it.

Summary of the swap:

  • engine and wiring harness from '92 325i
  • transmission, flywheel, clutch, slave cyl from '04 330i 6-speed manual
  • driveshaft front half from 528e with 3hp22 auto trans
  • driveshaft rear half from '85 318i manual
  • radiator from e36 325i (fits with some slight massaging of the frame rails)
  • stock expansion tank connected via a 3/4" steel pipe across the front of the engine and rubber hoses
  • engine and trans mounting brackets were homemade
  • oil pan, pump pickup, oil level sensor, dipstick from e34 525i
  • front exhaust manifold from e34 525i (rears are same on both e34 and e36)
  • m20 fan and fan clutch
  • aluminum t-stat housing to replace the stock plastic one
  • modified steel coolant pipe from an m52 to replace the silly "spider" hose
  • shift console/lever/linkage is hacked up BMW parts (there is probably a better way than how I did it)
  • modified e21 brake booster
  • downpipes were homemade (staying clear of the steering idler arm is tricky)

    I mounted the original e28 power steering pump, with a different pulley on it (pulled from a junkyard car with m5x engine) and a longer serpentine belt (1620mm).

    wiring guide