General information on inspecting cylinder walls - AH01.00-P-0300-01AL
ENGINE 640
- Glossy pressure points, smoothing
Individual blank points, e.g. in middle of cylinder or in area of cylinder head bolts.
Reuse crankcase.
- Visible streaks, friction marks
Starting from first piston ring, tapering to an end after about 30 mm. Traces of dry friction marks which cannot be felt, caused by oil film being washed off by fuel, e.g. during frequent cold starts associated with short-distance driving. These traces of friction marks which occur principally in area of cylinder head bolts and on pressure side are not a problem provided they are smoothed. The piston rings are not damaged.
Reuse crankcase.
- Ring-shaped impressions
Visible imprints in the upper and lower piston ring reversal range are not a reason for complaint.
Reuse crankcase.
- Circumferential bright, reflecting, polished upper surfaces of cylinder
Usually starting from the first piston ring, in the upper area of cylinder, with measurable partial cylinder wear.
Cylinder wall unusable.
- Roughened streaks, friction scoring
Starting from first and second piston ring, tapering to an end only in bottom part of cylinder. Traces of rubbing as described in item 2, which have advanced to signs of seizure. Piston rings may be damaged.
If damage can be felt, cylinder wall unusable.
- Single continuous traces of scratching
Caused by contamination, e.g. through reverse pulsation of soot particles out of exhaust.
Reuse crankcase.
- Piston seizure
Most of cylinder wall perceptibly roughened over the entire length. Material deposits and perceptible scoring marks on cylinder wall and at piston skirt.
Cylinder wall unusable.
- Brown discoloration of cylinder surface
Oil varnish is over large areas of cylinder contact surface and indicates, that engine was driven at high temperature level.
Reuse crankcase provided no impermissible cylinder distortion is present. Oil varnish above piston ring zone is normal and is not a reason for complaint.