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

Engine 112, 113, 122, 134, 135, 137, 166, 275, 285, 611, 612, 613, 628, 629, 639, 642, 646, 647, 648 

Pressure gloss marks, smoothings 

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

The crankcase can be reused.

Fig 1: Identifying Pressure Gloss Marks On Cylinder Walls

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Visible mottling, friction marks 

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

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

These traces of friction 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.

The crankcase can be reused.

Fig 2: Identifying Visible Mottling And Friction Marks On Cylinder Walls

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.

The crankcase can be reused.

Fig 3: Identifying Visible Imprints On Cylinder Barrel

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Rotary bright, specular, 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.

Fig 4: Identifying Cylinder Wear

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.

Fig 5: Identifying Friction Score Marks

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Continuous individual traces of scratch 

Caused by dirt, for example, through back pulsation of soot particles from the exhaust.

The crankcase can be reused.

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.

Brown coloring of cylinder upper surface. 

A 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.

The crankcase can be reused if no impermissible cylinder warping is visible

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