Pistons and Connecting Rods, Disassembling and Assembling

1. Piston rings
- Offset joint by 120°
- Install and remove with piston ring pliers
- Marking "TOP" to piston top
- Check joint clearance Fig. 1
- Check side clearance Fig. 2
2. Piston
- Checking Fig.,3
- Mark installation location to connecting rod and respective cylinder belonging to piston
- Tall side of the piston top points toward the middle of the cylinder block
- Install using funnel 3278 Fig. 5
3. Connecting rod
- Replace only as a set
- Mark respective cylinder to which the connecting rod belongs -B-
- Installation location: markers -A- must be positioned on top of each other
4. Connecting rod cover
- Note installation location
5. 30 Nm plus 1/4 turn (90 °)
- Always replace
- Oil thread bearing surface
- To measure radial play tighten to 30 Nm, however, do not continue turning
6. Bearing shell
- Note installation location
- Do not switch worn bearing shells
- Bearing shell retaining lips must be firmly placed in the recesses
- Axial clearance, new: 0.05 - 0.31 mm, max. wear: 0.40 mm
- Measure radial clearance with Plastigage. New: 0.02 - 0.07 mm, max. wear: 0.10 mm
- Do not change the position of the crankshaft when measuring radial play
7. Cylinder block
- Check cylinder bore Fig. 4
8. Piston pins
- If binding occurs, heat piston to 60°C
- Remove and install with flaring tool VW 222 a
9. Locking ring





Fig. 1 Piston ring - checking joint clearance
Special tools, equipment, test and inspection devices; required accessories:
- Feeler gauge

Test procedure
- Push ring at a right angle to cylinder wall, to bottom of cylinder opening, approx. 15 mm away from cylinder edge. In order to push in, use a piston without piston rings.





Piston ring Joint Clearance
New Max. wear
Plain compression ring (mm) 0.20-0.40 0.1
Tapered compression ring (mm) 0.20-0.40 0.1
Oil control ring (mm) 0.25-0.50 0.1





Fig. 2 Piston ring - checking side clearance
Special tools, equipment, test and inspection devices; required accessories
- Feeler gauge
- Clean piston ring groove before checking.





Piston ring Side clearance
New Max. wear
Plain compression ring (mm) 0.04-0.09 0.15
Tapered compression ring (mm) 0.03-0.06 0.15
Oil control ring (mm) 0.02-0.06 0.15

Fig. 3 Checking piston
Special tools, equipment, test and inspection devices; required accessories
- External micrometer 75 - 100 mm
- Measure approx. 6 mm from bottom edge, offset 90° to piston pin axis.
Maximum deviation from nominal size is 0.04 mm





Fig. 4 Checking cylinder bore
Special tools, equipment, test and inspection devices; required accessories
- Internal micrometer 50 - 100 mm

Test procedure
- Perform a crosswise measurement in 3 places in transverse direction -A- and lengthwise direction -B-.
Maximum deviation from nominal size is 0.08 mm





Note: The cylinder bore measurement cannot be taken if the cylinder block is fastened to the assembling trestle with engine retainer 3269; faulty measurements are possible.





Fig. 5 Installing piston with funnel 3278
Special tools, equipment, test and inspection devices; required accessories
- 3278 Piston installation tool

Note: If you are using a new funnel to install pistons, guide the piston with oiled piston rings through the funnel twice and, if necessary, remove resulting shavings. Only then should you install the piston with piston rings.

Procedure
- Manually push piston into oiled funnel. Tall side of piston top must point in direction of funnel spout -arrow-.
- Hold funnel (with inserted piston) at upper edge and push piston in with both thumbs.
- Push piston in until it protrudes approx. 15 mm below bottom edge of funnel.
- Start piston in its respective cylinder bore. Funnel spout -arrow- must point toward middle of cylinder block.
- Firmly place funnel on cylinder block and push piston in.

Piston and cylinder measurements





Table