Volkswagen Golf Service & Repair Manual: Checking pistons and cylinder bores

Volkswagen Golf Service & Repair Manual / 4- cylinder injection engine(1.4 1 direct inction. turbocharger) / Enginecrankshaft group, pistons / Pistons and conrods / Checking pistons and cylinder bores

Checking piston

–	Using a micrometre, measure approx. 10 mm from the lower edge, perpendicular to the piston pin axis.

Maximum deviation from nominal dimension: 0.04 mm

Checking pistons and cylinder bores

Piston diameter mm

Specification

74.42 ¹⁾

¹⁾ Dimensions without coating

Piston manufacturer Federal Mogul (thickness of 0.018 mm per side)

Piston manufacturer Mahle (thickness of 0.015 mm per side)

Measuring piston ring gap

–	Push piston ring at right angles to cylinder wall from above down into cylinder bore to approx. 15 mm from bottom end of cylinder.

–	Push in using a piston without piston rings.

Checking pistons and cylinder bores

Piston ring	New mm	Wear limit mm
Compression ring	0.20 ^{+ 0.15}	1.0
Oil scraper ring (2 parts)	0.20 ^{+ 0.20}	3.0
Oil scraper ring (3 parts)	0.50 ^{+/- 0.25}	3.0

Measuring ring-to-groove clearance

–	Clean annular groove of piston before check.

Checking pistons and cylinder bores

Piston ring	New mm	Wear limit mm
1st compression ring (piston ring manufacturer Federal Mogul)	0.050 … 0.090	0.15
1st compression ring (piston ring manufacturer Mahle)	0.035 … 0.085	0.15
2nd compression ring	0.030 … 0.070	0.15
Oil scraper rings (3 parts)	Not measurable
Oil scraper rings (2 parts)	0.04 … 0.08

Measuring cylinder bore

Risk of damage to the surface of the cylinder bore caused by incorrect machining.Do not machine cylinder bore (reboring, honing, grinding) with workshop equipment.

–	Using cylinder gauge -VAS 6078- take measurements at 3 positions diagonally in lateral direction -A- and longitudinal direction -B-.

Maximum deviation from nominal dimension: 0.08 mm

Checking pistons and cylinder bores

Cylinder bore diameter mm
Specification	74.5 + 0.015 ¹⁾ +0.005

Note

Cylinder bores must not be measured when cylinder block is mounted on engine and gearbox support -VAS 6095-, as measurements may be incorrect.

Removing and installing oil spray jets

Special tools and workshop equipment required Socket -T10545- Removing – Remove noi ...

Checking radial clearance of conrods

Special tools and workshop equipment required Plastigage Procedure – Remove conrod ...

Other materials:

Removing and installing pop-up cylinder
Special tools and workshop equipment required Drip tray Removing Note Removal and installation are described for the left side. Removal and installation on the right side are c ...

Removing and installing door opener illumination bulb -L108-/-L109-
Note Removal and installation are described for the left side. Removal and installation on the right side are carried out in the same way (mirror image of left side). Removing – Remove front ...

Safety regulations for crash sensors (pressure sensors) for front side airbags
The side airbag crash sensors respond to changes in pressure and must therefore be treated with particular caution. Observe the following: The correct installation position is vitally important: only install in the specified ...