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

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 Mercedes-Benz ML350, 2010 Mercedes-Benz ML350, 2009 Mercedes-Benz ML320, 2009 Mercedes-Benz GL320, and 2008 Mercedes-Benz ML320. However, it is still accessible from the selected car via links, so may be relevant.

Engine 112, 122, 134, 135, 166, 271.951, 272, 611, 612, 613, 628, 629, 639, 642, 646, 647, 648, 651 CD

Pressure gloss marks, smooth spots

Individual blank points, e.g. in the middle of the cylinder barrel or around the cylinder head bolts.

Continue to use crankcase.

Fig 1: View Of Pressure Gloss Marks & Smooth Spots

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Visible mottling, friction marks

Starting from reverse area of the upper piston ring tapering downwards.

Traces of dry friction marks which cannot be felt, caused by oil film being washed off by fuel, for example from many cold starts when driving short distances.

Friction marks occurring mainly around the cylinder head bolts and on the pressure side are not a problem provided that they are smoothed out.

The piston rings are not damaged.

Continue to use crankcase.

Fig 2: View Of Visible Mottling & Friction Marks

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Ring shaped imprints

Visible imprints on cylinder barrel in the upper and lower reverse area of piston rings are not a cause for complaint.

Continue to use crankcase.

Fig 3: View Of Ring Shaped Imprints

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Circumferential bright, reflecting, polished upper surfaces of cylinder

Starting from the reverse area of the upper piston ring with measurable, partial cylinder wear. The cylinder barrel is unusable.

Do not use the crankcase anymore.

Fig 4: View Of Circumferential Bright, Reflecting, Polished Upper Surfaces Of Cylinder

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. Progressive signs of friction lead to friction score marks.

Where these signs of friction are perceptible, the cylinder barrel is unusable.

The piston rings may be damaged.

Do not use the crankcase anymore.

Fig 5: View Of Roughened Mottling & Friction Scoring

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Continuous individual traces of scratch

Caused by soiling, for example, by the back-pulsation of soot particles from the catalytic converter or exhaust.

Continue to use 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.

The cylinder barrel is unusable.

Do not use the crankcase anymore.

Brown coloring of cylinder upper surface.

Brown coloration over large areas of the cylinder barrel is oil varnish and indicates that the engine has been driven at a high temperature level.

Oil varnish above piston ring zone is normal and is not a reason for complaint.

Reuse crankcase provided no impermissible cylinder distortion is present.