REMOVING AND INSTALLING/REPLACING ALL PISTONS
Remove engine 11 00 050.
Remove cylinder head 11 12 100.
Remove oil pump 11 41 000.
Remove conrod bearing caps in BDC position.
Installation: Conrods and bearing caps are marked
for matching cylinders. Conrod 1 is at sprocket
end. Cylinder reference numbers must always
be on same side.


11 00 050
11 12 100
11 41 000

Installation: Measure conrod bearings.
Use old conrod bolts to measure bearing play.
Install conrod bearing shells in connecting rod.
Place Type PG 1 Plastigage on crankshaft bearing
journal dried of oil.
Mount connecting rod on crankshaft.
Install conrod bearing caps that lubricating
grooves are adjacent to each other.
Oil bore in conrod end faces timing chain.

Tighten conrod bearing cap to specified torque¹).
Important: Don´t turn connecting rod or
crankshaft.
Take off bearing cap.
Read bearing play¹) from width of flattened
Plastigage with scale supplied.
Important: Replace old conrod bolts.


¹) See Specifications

Press up piston and connecting rod to remove.
Installation: Offset piston ring end gaps to each
other by 120°.
Arrow on piston crown faces timing chain.

Remove piston pin.
Installation: Piston pins are matched with pistons
and must not be mixed up.
Oil bore in connecting rod small end faces in
direction of piston´s arrow.
Important: Only install a piston of same make
and same weight class.
Weight class will be found on piston crown with
a + or - sign.

Piston Identification:
###Model BMW###Piston Dia.###Piston Crown###Code on Piston Crown
###630 CSi###89 mm, 3.504´´##flat##3.0 / 8.3
###633 CSi###89 mm, 3.504´´##flat##3.2 / 8.4
###633 CSi from 1980 models###89 mm, 3.504´´###recess 1.7 mm (0.067´´) deep###3.2 / 8.0

Check clearance¹) of installed piston.
###Model BMW###Make###Checkpoint A =
###630 CSi###Mahle KS###16 mm (0.630´´)
###630 CSi###Mahle KS###24.05 mm (0.947´´)
###633 CSi###Mahle KS###26 mm (1.024´´)
###633 CSi###Mahle KS###34.05 mm (1.340´´)


¹) See Specifications

Set micrometer of inside calipers to zero with
measured piston diameter.

Measure cylinder bore across diameter at 3
places with internal calipers.
Note installed piston clearance¹).


¹) See Specifications

Vehicles after change point in 1982
REMOVING AND INSTALLING
PISTON
Remove engine.
Take off cylinder head, oil pan and oil pump.
Remove connecting rod bearing cap and press out piston with connecting rod upwards.
Important!
Mark installed position of connecting rod to crankshaft, if conrod bearing shells do not
have to be replaced.

Remove circlip (1).
Press out piston pin.
Installation:
Piston pins and pistons are matched and must not be mixed up.
Install connecting rod, see 11 24 521.
Only install pistons of same make and same weight class.
Weight class is stamped with "+" or "-" in piston crown.


11 24 521

Important!
Check machined size (piston diameter)*.
Identification:

Engine	E*	Piston Cup	Dia.
		(mm)	(mm)
M 30 B 32	8.8	0 (flat piston)	89
M 30 B 34	8.0	5.3	92

* See Specifications

Check piston installed clearance*.

Engine	Make	Checkpoint A
		mm (in.)
M 30 B32	Mahle	26.00 (1.024)
	KS	33.95 (1.337)
M 30 B 34	Mahle	14.00 (0.551)

* See Specifications

Set internal calipers to zero on micrometer with the measured piston diameter.

Measure cylinder bore with internal calipers at bottom, center and top in forward and
rotational directions.
Check piston installed clearance*.


* See Specifications

Lubricate piston and piston rings with oil.
Offset piston ring end gaps by 120°.
Compress piston rings with Special Tool 11 2 260.

Install piston that arrow faces timing chain.