Haynes Mini - Page 37

2B
Chapter 2 Part B:
Engine removal and overhaul procedures
Engine general
Engine codes:
85H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 848 cc engines
99H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 998 cc engines
10H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1098 cc engines
12H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1275 cc engines
12A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1275 cc engines
Valves
Valve head diameter:
Inlet:
85H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27.76 to 27.89 mm
10H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.23 to 29.36 mm
12H:
1275 GT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.20 to 33.32 mm
Cooper S Mk III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35.58 to 35.71 mm
12A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35.58 to 35.71 mm
Exhaust:
85H, 99H and 10H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.40 to 25.53 mm
12H:
1275 GT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.24 to 29.37 mm
Cooper S Mk III . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.83 to 30.96 mm
12A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.25 to 29.38 mm
Valve stem diameter:
Inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.094 to 7.107 mm
Exhaust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.082 to 7.094 mm
Valve stem-to-guide clearance:
Inlet:
85H, 99H and 10H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.038 to 0.064 mm
12H and 12A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.040 to 0.080 mm
Exhaust:
85H, 99H and 10H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.051 to 0.076 mm
12H and 12A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.040 to 0.080 mm
Valve seat angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45º
Camshaft and tappets - removal, inspection and refitting . . . . . . . . 9
Crankshaft - refitting and running clearance check . . . . . . . . . . . . . 17
Crankshaft - removal and inspection . . . . . . . . . . . . . . . . . . . . . . . . . 12
Cylinder block/crankcase - cleaning and inspection . . . . . . . . . . . . . 13
Cylinder head - dismantling, cleaning, inspection and reassembly . 8
Engine - initial start-up after overhaul and reassembly . . . . . . . . . . . 19
Engine and automatic transmission - separation and reconnection . 6
Engine and manual transmission - separation and reconnection . . . 5
Engine overhaul - preliminary information . . . . . . . . . . . . . . . . . . . . . 7
Engine overhaul - reassembly sequence . . . . . . . . . . . . . . . . . . . . . . 15
Engine/transmission - removal and refitting . . . . . . . . . . . . . . . . . . . 3
Engine/transmission removal - preparation and precautions . . . . . . 2
Engine/transmission (with front subframe) - removal and refitting . . 4
General information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Main and big-end bearings - inspection and selection . . . . . . . . . . . 14
Oil pump - removal, inspection and refitting . . . . . . . . . . . . . . . . . . . 10
Piston/connecting rod assemblies - refitting and big-end bearing
clearance check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Piston/connecting rod assemblies - removal, inspection, separation
and reconnection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Piston rings - refitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2B•1
Specifications
Contents
Easy, suitable for
novice with little
experience
Fairly easy, suitable
for beginner with
some experience
Fairly difficult,
suitable for competent
DIY mechanic
Difficult, suitable for
experienced DIY
mechanic
Very difficult,
suitable for expert DIY
or professional
Degrees of difficulty
5
4
3
2
1