Oil Pump

Remove oil pan, front engine covers and timing chain as previously outlined. Remove oil pump drive sprocket and chain. Remove oil pump.
Remove pressure regulator plug, spring and piston. Remove pump cover and thoroughly clean and inspect all components. Check clearance between inner and outer rotors. If clearance exceeds maximum specified, replace rotors.
Check clearance between outer rotor and pump body and clearance between rotor sealing face and mating surface of pump body and pump cover. If either clearance exceeds maximum specified, replace pump body.

Fig 1: View of Oil Pump Assembly
Courtesy of BMW OF NORTH AMERICA, INC.
To remove sprocket flange, pull with suitable tool. Install flange so that distance between sprocket side of flange and sealing side of inner rotor is 1.744±.004" (44.30±.10 mm).
Check free length of regulator spring, if less than specified, replace spring. To assemble pump, reverse removal procedure. Attach oil pump to crankcase and install sprocket and chain. Chain should slightly depress when pushed in with thumb.
If chain depresses more than recommended, remove pump and install shims between pump and crankcase mounting points. Make sure oil holes line up on front shim. Rear shim must be same thickness as front. To install remaining components, reverse removal procedure.

Fig 2: Checking Inner to Outer Rotor Clearance with Feeler Gauge
Courtesy of BMW OF NORTH AMERICA, INC.

OIL PUMP SPECIFICATIONS

Application		Measurement In. (mm)
Rotor-to-Rotor Clearance		005-.008 (.12-.20)
Rotor-to-Housing Clearance
	Radial	006-.011 (.150-.275)
	Axial	0014-.0037 (.035-.095)
Regulator Spring Free Length		2.677 (67.99)