Inspecting Cylinders With Inspection Lamp (Borescope)

- Remove spark plugs.
- Piston position to BDC.

Piston Position Table
- Marking index on dampner: 0
Pistons in BDC: 4 and 7
- Marking index on dampner: 90
Pistons in BDC: 8 and 2
- Marking index on dampner: 180
Pistons in BDC: 1 and 6
- Marking index on dampner: 270
Pistons in BDC: 5 and 3

- Connect Motoskop and lens probe.
Motoskop TW 12 V to car battery.
Motoskop TW 220 V to mains.
- Insert lens probe into cylinder.
- Cylinders, inspect and assess, see NOTE below.

Commercially Available Tool
- Cylinder inspection lamp
Karl Storz GmbH,
78532 Tuttlingen
Motoskop TW (cold light) with lens probe
103 26 CT (210 mm)

NOTE:
- If complaints are received regarding an engine because of noises, overheating, oil consumption etc., it is good practice to perform a visual inspection with a cylinder inspection lamp with the cylinder head installed.
- The information which follows is designed to help in assessing the cylinder walls, in taking a proper professional decision regarding the condition and further use of the crankcase.
- If it is not possible to assess the cylinders with sufficient certainty by means of a visual inspection with the cylinder inspection lamp, the cylinder head should then be removed.

1. Normal condition
- Mat grey surface, no honing pattern.






2. Bright pressure marks, smoothing
- Individual bright points e.g. in the middle of the cylinder or in the area of the cylinder head boil pipes.
- Continue using crankcase.






3. Bright cylinder surfaces, polished and reflective all round
- Usually starting from the first piston ring, in the top area of cylinder, with measurable partial cylinder wear.
- Cylinder wall unserviceable.






4. Visual streaks, traces of rubbing
- Starting from first piston ring, extending for about 30 mm.
- Traces of dry rubbing which cannot be felt, caused by fuel ablution of the oil film, e.g. frequent cold starting in short-distance driving.
- These traces of rubbing, which are likely to be found in the area of the cylinder head bolts and on the pressure side, are acceptable if smoothed.
- The piston rings are not damaged.
- Continue using crankcase.






6. Roughened streaks, traces of seizure
- Starting from the first and second piston ring and extending initially to the bottom part of the cylinder.
- Traces of rubbing as described in "4" (above) have progressed to seizure.
- Piston rings may be damaged.
- If the streaks can be felt, the cylinder wall is unserviceable.






6. Ring-shaped impressions
- Visible in the top and bottom piston ring reversal area, are acceptable.
- Continue using crankcase.


7. Traces of individual, continuous scratches
- Caused by dirt, e.g. by soot particles being pulsated back out of the exhaust.
- Continue using crankcase.


8. Piston seizure
- Cylinder wall usually roughened over the entire length to the extent that this can be felt.
- Material accumulation and traces of seizure on cylinder wall and piston skirt which can be felt.
- Cylinder wall unserviceable.


9. Brown discoloration of cylinder surfaces
- Oil vanish exists over considerable areas of the cylinder wall and indicates that the engine has been driven at a very high temperature level.
- Continue using crankcase provided no impermissible cylinder distortion exists.
- Oil varnish above the piston ring zone is normal and is acceptable.