Volkswagen Workshop Service and Repair Manuals

Pistons and conrods - remove and install   Note All contact and sliding surfaces must be lubricated with oil before assembly work.   WARNING Always replace self-locking nuts and screws subject to angular torque

1 -

Piston

q	Check → Fig.

q	Mark assembly position and correspondence with the cylinder.

q	Arrow on piston upper part points to the pulley side.

q	Install with ring compressor.

2 -	Piston pin

q	In case of difficulties in the removal, heat the piston to 60°C.

q	Remove and install with Pin or VW 010-206 -10-206-.

3 -	Piston pin retaining ring

q

Replace.

4 -

Conrod

q	Replace in pairs only.

q	Mark corresponding position relative to cylinder -A-.

q	Assembly position: marks -B- point to the flywheel side.

q	On conrods without marks -B-, the installation position is the painted faces (conrod and cap), facing the crankcase venting device side.

q	Besides defining the pair (conrod and cap), colors painted on conrods and caps also define the position (conrod in cap).

q	Piston/conrod axial clearance; 0.20...0.40 mm wear limit 0.50 mm.

q	It is separated from cap by the breakage process → Fig.

5 -	Bearing shell

q	Check assembly position.

q	Do not mix used bearing shells in case they are reused, mark.

q	Install bearing shells centrally.

q	Measure radial clearance using Plastigage: new: 0.020...0.061 mm wear limit: 0.004 in. Do not rotate crankshaft while measuring radial clearance.

6 -	Cylinder block

q	Check cylinder bore → Fig.

q	Piston and cylinder dimensions → Chapter.

7 -	Conrod cap

q	Check assembly position.

q	Due to the rupture process applied to the conrods, the cap can be assembled in only one position and only on the respective conrod.

q	Besides defining the pair (cap and conrod), colors painted on caps and conrods also define the position (cap in conrod).

q	It is separated from body by the breakage process → Fig.

8 -	30 Nm + 90°

q	Replace after each removal.

q	Lubricate threads and stop surfaces.

q	Tighten to 30 Nm to measure radial clearance, but do not apply the angular torque.

9 -	Oil scraper rings

q	Remove and install manually and carefully the 3-part oil scraper rings.

q	„TOP“ mark must point towards piston crown.

q	Check opening between ends → Fig.

q	Check ring clearance in the piston groove → Fig.

10 -	Compression rings

q	Move openings 120°.

q	Remove and install compression rings with compression ring pliers.

q	„TOP“ mark points towards the piston crown.

q	Check opening between ring ends → Fig.

q	Check ring clearance in the piston groove → Fig.

Typical conrods -A- Conventional conrods (smooth separation surface). -B- Industrially-cracked conrods (rough separation surface).

Openings of piston ring ends - check –  Insert the ring at right angle from top to the cylinder lower opening, with a distance of approx. 15 mm from cylinder lower edge. BAH and BPA engines

Piston ring	Wear limit
1. Compression ring	0.04 in
2. Compression ring	0.04 in
Oil scraper ring	0.04 in

CCRA engine

Ring		Opening between ends
		new	wear limit
1st compression ring	mm	0,20...0,35	1,0
2nd compression ring	mm	0,20...0,40	1,0
Oil scraper ring	mm	0,25...0,75	1,0

Check ring clearance in the piston groove Clean ring groove on piston before the test. BAH and BPA engines

Piston ring	Wear limit
1. Compression ring	0.01 in
2. Compression ring	0.01 in
Oil scraper ring	0.01 in

CCRA engine

Ring		Groove clearance
		new (with Mahle piston)	new (with Federal Mogul piston)	wear limit
1st compression ring	mm	0,030...0,080	0,040...0,080	0,15
2nd compression ring	mm	0,020...0,060	0,020...0,060	0,15
Oil scraper ring	mm	0,010...0,150	0,010...0,150	0,20

Check piston Special tools and workshop equipment required t  External micrometer 60...90 mm –  Measure to approx. 10 mm from lower corner, displaced by 90° in relation to the piston pin axis. Divergence in max. nominal measure 0.00 in. Nominal measure → Chapter.

Conrod journals: installation –  -1- Bearing shell with bore for piston pin lubrication groove -arrow-. –  -1 and 2- Bearing shell positions on conrod and conrod cap -a- right and left sides equal. –  -a- Maximum tolerance = 0.2 mm.   Note Both for conrod and conrod cap, bearing shells provide bores to prevent erroneous installation.

Check cylinder bores Special tools and workshop equipment required t  Precision internal micrometer 50..0.100 mm –  Measure at three different points, in cross pattern, in transversal -A- and longitudinal -B- directions, with a distance of 10.0 mm from upper and lower edges -C-. Tolerances in relation to max. nominal measure 0.00 in. Nominal measure → Chapter.   Note The cylinder bore should not be measured while the cylinder block is secured to the assembly stand with the Support -VW 540- or Rotary stand for engine and gearbox -VAS 6095-, because this can produce wrong measures.