Chapter 2 Part B: General engine overhaul procedures - e34.de

1 2 BGeneralCylinder compression pressure (all engines) ..10 to 11 barsOil pressure (all engines)At idle .. to barsRunning (for example, at 4000 rpm) ..4 bars or above (typically) cylinder head warpage limitExcept M40 engine .. mm M40 engine .. mmMinimum cylinder head thickness (do not resurface the head to a thickness less than listed)M10 and M30 engines .. mmM20 engines .. mmM40 engine .. mmValvesValve stem diameter (standard)M10 and M30 engines .. mmM20 engine .. mmM40 engineIntake .. mmExhaust .. mmMinimum valve margin widthIntake .. mmExhaust .. mmValve stem maximum lateral movement (see text) .. mmValve face angleIntake ..45 Exhaust.

2 45 Chapter 2 Part B: General engine overhaul proceduresCompression check .. 3 Crankshaft - inspection .. 19 Crankshaft - refitting and main bearing oil clearance check .. 24 Crankshaft - removal .. 13 Crankshaft rear oil seal - refitting .. 25 cylinder head and components - cleaning and inspection .. 9 cylinder head - dismantling .. 8 cylinder head - reassembly .. 11 cylinder honing .. 17 engine - removal and refitting .. 5 engine block - cleaning .. 15 engine block - inspection .. 16 engine overhaul - alternatives .. 6 engine overhaul - dismantling sequence .. 7 engine overhaul - General information .. 2 engine overhaul - reassembly sequence.

3 21 engine removal - methods and precautions .. 4 General information .. 1 Initial start-up and break-in after overhaul .. 27 Intermediate shaft - refitting .. 23 Intermediate shaft - removal and inspection .. 14 Main and connecting big-end bearings - inspection .. 20 Piston rings - refitting .. 22 Pistons/connecting rods - inspection .. 18 Pistons/connecting rods - refitting and big-end bearing oil clearance check .. 26 Pistons/connecting rods - removal .. 12 Valves - servicing .. 102B 1 Easy,suitable fornovice with littleexperienceFairly easy,suitablefor beginner withsome experienceFairly difficult,suitable for competentDIY mechanicDifficult,suitable forexperienced DIYmechanicVery difficult,suitable for expertDIY or professionalDegrees of difficultySpecificationsContentsCamshaft and rocker armsCamshaft bearing oil clearance.

4 To mmCamshaft endfloatM10 engine .. to mmM20 engine .. mm maximumM30 engine .. to mmM40 engine .. to mmRocker arm radial clearance .. to mmCrankshaftEndfloatM10 and M30 engines .. to mmM20 and M40 engines .. to mmMain bearing journal diameter (standard)M10 enginesRed classification .. to mmBlue classification .. to mmM20 enginesRed classification .. to mmBlue classification .. to mmM30 and M40 enginesYellow classification .. to mmGreen classification .. to mmWhite classification .. to mmMain bearing journal diameter undersizes1st undersize .. mm2nd undersize .. mm3rd undersize (where applicable) .. mmMain bearing oil clearanceM10 and M20 engines.

5 To mmM30 and M40 engines .. to mmConnecting rod journal diameter (standard)M10 and M30 engines .. to mmM20 and M40 engines .. to mmConnecting rod journal diameter undersizes1st undersize .. mm2nd undersize .. mm3rd undersize (where applicable) .. mmConnecting rodsConnecting rod side play (all engines) .. mmConnecting big-end bearing oil clearanceM10 engines .. to mmM20 and M30 engines .. to mmM40 engines .. to mmEngine blockCylinder bore - diameter (standard)M10/B18 engine .. to mmM20/B20 engine .. to mmM20/B25 engine .. to mmM30/B25 engine .. to mmM30/B28 engine .. to mmM30/B30M engine .. to mmM30/B34 engine .

6 92 00 to mmM30/B35M engine .. to mmM40/B16 engine .. to mmM40/B18 engine .. to mmCylinder out-of-round limit (maximum)M20/B20 engine .. mmM20/B25 engine .. mmAll other engines .. mmCylinder taper (maximum)M20/B20 and M20/B25 engines .. mmAll other engines .. mm2B 2 General engine overhaul proceduresPistons and piston ringsPiston diameter (standard)M10 engines .. mmM20 enginesB20 .. mmB25 .. mmM30 enginesB30 MAlcan .. mmKS .. mmB35 MAlcan .. mmMahle .. mmM40 enginesFactory stage 0 .. mmFactory stage 00 .. mmPiston-to- cylinder wall clearanceNewM10 and M30 engines .. to mmM20 and M40 engines .. to mmService limitExcept B25 engine .

7 MmB25 engine .. mmPiston ring end gapM10 engineTop compression ring .. to mmSecond compression ring .. to mmOil ring .. to mmM20 engineAll rings .. to mmM30 engineTop compression ring .. to mmSecond compression ring .. to mmOil ring .. to mmM40 engineTop compression ring .. to mmSecond compression ring .. to mmOil ringB16 engine .. to mmB18 engine .. to mmPiston ring side clearanceM10 engineTop compression ring .. to mmSecond compression ring .. to mmOil ring .. to mmM20 engineTop compression ring .. to mmSecond compression ring .. to mmOil ring .. to mmM30 engineTop compression ring .. to mmSecond compression ring.

8 To mmOil ring .. to mmM40 engineTop compression ring .. to mmSecond compression ring .. to mmOil ringB16 engine .. to mmB18 engine ..Not measuredTorque wrench settingsNmMain bearing cap-to- engine block bolts*M10, M20 and M30 engines ..60M40 enginesStage 1 ..20 Stage 2 ..Angle-tighten an additional 50 General engine overhaul procedures 2B 32 BTorque wrench settings (continued)NmConnecting rod cap bolts/nutsM10 and M30 engines ..55M20 and M40 enginesStage 1 ..20 Stage 2 ..Angle-tighten an additional 70 Camshaft bearing caps (M40 engine ) ..10 Intermediate shaft sprocket-to-shaft bolt (M20 engine ) ..60 Oil supply tube bolt(s)M6 (normal) and M8 (banjo).

9 10M5 ..5* BMW recommend that the main bearing bolts are renewed as a matter of 4 General engine overhaul procedures1 General informationIncluded in this Part of Chapter 2 are thegeneral overhaul procedures for the cylinderhead and engine internal information ranges from adviceconcerning preparation for an overhaul andthe purchase of new parts to detailed,paragraph-by-paragraph procedures coveringremoval and refitting of internal componentsand the inspection of following Sections have been writtenbased on the assumption that the engine hasbeen removed from the vehicle. Forinformation concerning in-vehicle enginerepair, as well as removal and refitting of theexternal components necessary for theoverhaul, see Chapter 2A, and Section 7 ofthis Specifications included in this Part areonly those necessary for the inspection andoverhaul procedures which follow.

10 Refer toPart A for additional engine overhaul - General informationIt s not always easy to determine when, orif, an engine should be completelyoverhauled, as a number of factors must mileage is not necessarily anindication that an overhaul is needed, whilelow mileage doesn t preclude the need for anoverhaul. Frequency of servicing is probablythe most important consideration. An enginethat s had regular and frequent oil and filterchanges, as well as other requiredmaintenance, will most likely give manythousands of miles of reliable , a neglected engine may requirean overhaul very early in its oil consumption is an indicationthat piston rings, valve seals and/or valveguides are in need of attention.