Crankcase and cylinder head,  OM617

Evaluation of cylinder bores



01—020 Evaluation of cylinder bores


Tightening torques
Cap nuts for injection lines
Nuts for cylinder head cover
Threaded ring for prechamber in cylinder head
Injection nozzle in prechamber


Special tools


Box wrench socket, open, 17 mm, 1/2″ square for injection lines
om617 - 0016-1.jpg
000 589 68 03 00
Socket 27 mm, 1/2″ square
001 589 65 09 00
Socket wrench for threaded ring of prechamber
615 589 00 07 00
PUIIer for prechambers
615 589 00 33 00


Conventional tool


Cylinder illuminating lamp
Karl Storz GmbH, 7200 Tuttlingen MotoskopTW(Kaltlicht)
with lens probes 103 26 CW (750 mm) and 103 26 CT (210 mm).




A visual checkup can be made with cylinder head in place by means of a cylinder illuminating lamp. For this purpose, the prechambers must be removed (01-417).
om617 - 0016-2.jpg




01.8-020/1 F2




When evaluating scored or streaky cylinder walls, it is often difficult for a workshop to decide whether the damage is already extensive and requires removal or repair of the engine, or whether the evidence is harm­less. The following instructions will help in making an expert and correct decision.
om617 - 0017-1.jpg


With regard to marks on cylinder walls, the first im­portant difference is between “optical streaks” and “seizure streaks”. As a rule, “optical streaks” are about 3 mm wide, they are produced by the piston ring gaps and do not destroy honing structure; “seizure streaks”, however, obliterate honing structure.
With streaks in direction of “land” (in direction of piston pin) shaft streaks or seizures are not possible, since there is no contact between piston skirt and cylinder liner.


01.8-020/2 F2