Pistons and Connecting Rods, Disassembling and Assembling
Pistons and connecting rods, disassembling and assembling
1- Piston ring
- Offset gaps by 120°
- Remove and install using piston ring pliers
^ "TOP" faces piston crown
^ Ring gap, checking => Fig. 1
^ Ring to groove clearance checking => Fig. 2
^ 2 or 3 part oil scraper ring: mixed installations permitted
2- Piston
^ Checking => Fig. 3
- Mark installation position and cylinder number
^ Arrow on piston crown points to pulley end
- Install using piston ring clamp
3- Connecting rod
- Only replace as a set
- Mark cylinder number -B-
^ Installation position:
Marking -A- faces towards pulley end
4- Connecting rod bolt
- For engine code AEG
5- Connecting rod bearing cap
- Mark cylinder number -B-
- Installation position:
- Marking -A- faces towards pulley end
6- 30 Nm (22 ft. lbs.) + 1/4 turn (90°) further
- Only for engine code AEG
- Always Replace
- Oil threads and contact surfaces
^ To measure radial clearance tighten to 30 Nm (22 ft. lbs.) but no further
- 90 ° additional angle can be measured with torque angle meter i.e., Hazet 6690
7- Conrod bolt 30 Nm (22 ft lb) + 1/4 turn (90 °)
- For engine codes AVH, AZG
- Always replace
- Oil threads and contact surfaces
- To measure radial clearance tighten to 30 Nm (22 ft lb) but no further.
- 90 ° additional angle can be measured with torque angle meter i.e., Hazet 6690
8- Pressure relief valve
^ 27 Nm (20 ft. lbs.)
^ Opening pressure: 2.5 to 3.2 bar (36 to 46 psi)
9- Oil spray jet
^ for piston cooling
10- Bearing shell
- Note installation position
- Do not interchange used bearing shells
- Insert bearing shells centrally
- Ensure retaining lugs fit tightly in recesses
- Axial clearance
New: 0.05 to 0.35 mm
Wear limit: 0.40 mm
- Check radial clearance with Plastigage:
New: 0.01 to 0.06 mm
Wear limit: 0.12 mm
Do not rotate crankshaft when checking radial clearance
11- Engine block
^ Checking cylinder bores -> Fig. 4
^ Piston and cylinder dimensions
Honing Piston Cylinder Bore
Dimension Diameter Diameter
Basic Dimension mm 82.465 1) 82.510
1st Oversize mm 82.965 1) 83.010
1) - Dimension without graphite coating (thickness 0.02 mm). The graphite coating wears away.
12- Circlip
13- Piston pin
^ If difficult to remove, heat piston to 60°C (140°F)
^ Remove and install with VW 222a
Fig. 1 Piston ring gap, checking
Special tools, testers, measuring instruments and auxiliary items required
^ Feeler gauges
- Squarely push down on piston ring from above to approx. 15 mm from bottom end of cylinder bore.
Fig. 2 Ring to groove clearance, checking
Clean groove before check.
Fig. 3 Piston, checking
Special tools, testers, measuring instruments and auxiliary items required
^ MICROMETER 75 TO 100 mm (2.95 to 3.95 in.)
- Measure pistons approx. 10 mm from the lower edge of skirt, at 90° angle to the piston pin axis.
^ Deviation from nominal dimension max. 0.04 mm
Fig. 4 Cylinder bores, checking
Special tools, testers, measuring instruments and auxiliary items required
^ Internal Dial Gauge 50 TO 100 mm (2.95 to 3.95 in.)
- Measure bore at 3 locations in both directions -A- across the engine and -B- in line with crankshaft.
^ Deviation from nominal dimension max. 0.08 mm
Note:
Do NOT measure the cylinder bores when the engine block is mounted on a repair stand using the VW 540 adapter bracket, inaccurate measurements will result due to the uneven bending of the engine block on the repair stand.
Piston and cylinder dimensions
