VW Golf manuals

Volkswagen Golf Service & Repair Manual: 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.
   
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Checking radial clearance of conrods
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Other materials:

Removing and installing lower rear lid trim
Special tools and workshop equipment required     –  Remove upper rear lid trim → Chapter. –  Remove warning triangle.   ...

Safety precautions during road tests in which test and measuring equipment is used
Risk of injury due to unsecured test and measuring equipment If a front passenger airbag is triggered during an accident, unsecured test and measuring equipment can become dangerous projectiles. –  Secure test and measuring equipment with seat belts on ...

Rear axle
Overview - rear axle, torsion beam axle I -  → Chapter „Axle beam“ II -  → Chapter „Suspension strut, shock absorber, spring“ III -  → Chapter „Wheel bearing assembly, trailing a ...

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