General information on inspecting cylinder walls - AH01.00-P-0300-01AMG

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Pressure gloss marks, smooth spots
Individual blank points, e.g. in middle of cylinder or in area of cylinder head bolts.

Reuse crankcase.

Fig 1: Identifying Pressure Gloss Marks On Cylinder Walls
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Visible mottling, 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.

Fig 2: Identifying Visible Mottling And Friction Marks On Cylinder Walls
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Ring shaped imprints
Visible imprints in the upper and lower piston ring reversal range are not a reason for complaint.

Reuse crankcase.

Fig 3: Identifying Ring Shaped Imprints On Cylinder Walls
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Rotary bright, specular, 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.

Fig 4: Identifying Rotary Bright, Specular, Polished Upper Surfaces On Cylinder Walls
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Roughened mottling, 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.

Fig 5: Identifying Roughened Mottling, Friction Scoring On Cylinder Walls
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Continuous individual traces of scratch
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 coloring of cylinder upper 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.