Connecting Rod: Service and Repair

Component Notes And Information
^ During service procedures, refer to the illustration above and the information below.
^ When stripping and assembling the engine, mount it on an engine stand using 3269 engine bracket.

1 Piston ring
- Offset ring gaps 120°
- Remove and install using piston ring pliers
- "TOP" faces towards piston crown
- Ring gap, checking: refer to Fig. 1 below
- Ring to groove clearance, checking: refer to Fig. 2 below
2 Piston
- Checking: refer to Fig. 3 below
- Mark orientation to conrod and cyl. number using marking pen
- High point of piston crown faces centerline of cylinder block
- Install using 3278 piston fitting tool refer to Fig. 5 below
3 Connecting rod
- Only replace as a set
- Mark cylinder number -B-
- Installation position:
- -A- marks must align above one another
4 Connecting rod bearing cap
- Note installation position
5 Connecting Rod Bolt
- Tighten to: 30 Nm + 1/4 turn (90°)
- Always replace
- Oil threads and contacting surfaces
- When measuring radial clearance: tighten to 30 Nm (22 ft lb) but no further
6 Bearing shell
- Note installation position
- Do not interchange used bearing shells
- Bearing shell lugs must fit tightly in the recesses
- Axial clearance:
New: 0.05 to 0.31 mm
Wear limit: 0.40 mm
- Check radial clearance with Plastigage:
New: 0.02 to 0.07 mm
Wear limit: 0.10 mm

CAUTION: Do not rotate crankshaft while checking radial clearance

7 Cylinder block
- Cylinder bores, checking: refer to Fig. 4 below
- Piston and cylinder dimensions: refer to Piston And Cylinder Dimensions Table below
8 Piston pin
- If difficult to remove, heat piston to 60°C (140°F)
- Remove and install using VW 222a drift
9 Circlip

Procedures





Fig. 1 Piston Ring Gap, Checking
Special Tools, Testers And Auxiliary Items
- Feeler gauge set

Test Sequence
- Using a piston without rings, squarely push ring down into cylinder to a depth of approx. 15 mm (0.6 inch) from lower end of cylinder

Piston Ring Gap Dimensions Table





- Insert feeler gauges into ring gap to determine clearance value





Fig. 2 Ring To Groove Clearance, Checking
Special Tools, Testers And Auxiliary Items
- Feeler gauge set

Piston Ring To Piston Dimensions Table





- Clean ring grooves before checking





Fig. 3 Piston, Checking
Special Tools, Testers And Auxiliary Items
- 75 to 100 mm micrometer

- Measure pistons approx. 6 mm from lower edge of skirt, at 901 axis to piston pin
Deviation from nominal dimension: 0.04 mm (max.)





Fig. 4 Cylinder Bore, Checking
Special Tools, Testers And Auxiliary Items
- 50 to 100mm Inside dial gauge

Test Sequence
- Measure bore at 3 locations in both directions -A- across the block and -B- in line with crankshaft
Deviation from nominal dimension: 0.08 mm (max.)

CAUTION:
^ DO NOT measure cylinder bores with the block mounted on an engine stand.
^ Natural distortion due to hanging weight will cause measurement errors.





Fig. 5 Pistons, Installing
Special Tools, Testers And Auxiliary Items
- 3278 Piston installation tool

CAUTION: Before using a new piston installation tool for the first time, first pass a piston (with oiled rings) twice through the tool. Then, thoroughly clean any resulting metal shavings or dirty oil. Only then should the tool be brought into operation! Ensure that all tools and components involved in piston installation are clean.

Work Sequence
- Offset piston ring gaps 120°
- Oil piston installation tool and insert piston by hand
High point on piston crown must face lug on tool -arrow-
- Hold tool (with piston inserted) on upper edge and press piston into tool using both thumbs
- Push piston in until it protrudes approx. 15 mm from the lower edge of the tool
- Orient piston to appropriate cylinder bore
Lug on tool -arrow- must face toward center of block
- Press tool firmly against cylinder block and then push piston completely into the cylinder

Piston And Cylinder Dimensions Table