Connecting Rod: Service and Repair

Piston and Connecting Rod Component Overview






1 Connecting rod bolt - 30 Nm plus an additional 90°

• Replace

• Lubricate threads and contact surface

• Use old bolt to measure radial play

• Tighten to 30 Nm to measure radial play, do not turn further

2 Connecting Rod Bearing Cap

• Affiliation to the cylinder mark - B -

• Installation position: Markings - A - must align

3 Bearing Shells

• Do not interchange used bearing shells (mark)

• Bearing shell retaining tabs must be firmly seated in the notches

• Installation position: Retaining tabs of both bearing shells lie on the same side of the connecting rod

• Axial play new: 0.05 to 0.31 mm; wear limit: 0.40 mm

• Measure radial clearance with Plastigage

• Do not turn crankshaft when measuring radial play

• Radial clearance, new: 0.02 to 0.07 mm; wear limit: 0.10 mm

• Replacement parts are color coded "yellow" for lower and "red" for upper

4 Connecting Rod

• With oil hole for piston pin lubrication

• Only replace as set

• Affiliation to the cylinder mark - B -

• Installation position: Mark - A - faces toward the shallow side of the piston (the shallow side of the piston head faces the cylinder block center)

5 Circlip

6 Piston Pin

• If tight, heat piston to 60 °C / 140 °F

• Removing and installing using a drift (VW 222 A)

7 Piston

• Mark installed location to connecting rod and affiliation to cylinder

• Shallow side of piston head faces cylinder block center

• Piston and cylinder dimensions, refer to => [ Piston and Cylinder Dimensions ] [1][2]Piston, Engine

8 Piston Rings

• Compression rings

• Offset gaps by 120°

• Use piston ring pliers for removal and installation

• Mark "TOP" must face toward piston head

9 Piston Ring

• Oil scraping ring

• 3-part

• Install upper steel ring so gap is offset by 120° to neighboring compression ring

• Offset all oil scraping ring component gaps to each other

Piston Ring Gap, Checking





- Push ring squarely from above down to approximately 15 mm from bottom end of cylinder. To do this use a piston without rings.

- Use a feeler gauge to measure.






Piston Ring Groove Clearance, Checking





- Clean the ring groove of piston before checking.

- Use a feeler gauge to measure.






Pistons, Checking





- Measure pistons approximately 6 mm from bottom edge and at points offset by 90° to piston pin axis.

- Use external micrometer 75 to 100 mm to measure.

• Maximum deviation from nominal dimension: 0.04 mm.

Cylinder Bore, Checking





- Measure bores at 3 locations in both directions - A - across engine and - B - in line with crankshaft.

- Use internal dial gauge 50 to 100 mm to measure.

• Maximum deviation from nominal dimension: 0.08 mm.

Installing Piston with Piston Insertion Funnel (T10147)





• If a new funnel is used, next guide pistons with oil piston rings through funnel twice and remove resulting metal shavings if necessary. Only then install piston with piston rings.

- Push piston by hand into oiled piston installation tool.

• Flat side of piston crown must face toward funnel pin - arrow -.

- Hold funnel (with piston inserted) on upper edge and press piston in with both thumbs.

- Push piston in until it protrudes approximately 15 mm from lower edge of funnel.

- Insert piston into appropriate cylinder bore.

• Funnel pin - arrow - must point toward center of cylinder block.

- Press funnel tightly against cylinder block and push piston in.