01—417 Removal and installation of pre-chambers
 
 

 
 
Data
 
 

 
 
Pre-chamber standout on cylinder head dimension "c" 7.8—8.4 mm
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Tightening torques
Coupling nuts of injection lines Nuts for cylinder head cover Pre-chamber in cylinder head (threaded ring) Nozzle holder in pre-chamber
Special tools
Open box wrench insert, 17 mm, 1/2" square socket for injection lines
Socket 27 mm, 1/2" square socket
Socket wrench for threaded ring of pre-chamber
Puller for pre-chamber
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Nm
25
15
150-180
70-80
000 589 68 03 00
001  589 65 09 00 615 589 00 07 00
615 589 00 33 00
 
 

 
 
Note
 
 

 
 
The prechambers of engines 616.912 and 617.912 may not be installed on these engines.
For identification, a code number (617/03) is shown at upper flange of pre-chamber.
In addition, the pre-chamber can be identified by means of the smaller bore (0—9 mm dia.) for glow
Plug.                                            A Prechamber
engines 616.912/617.912
B Prechamber
engines 61 7.950/951 /952
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1053-8622A2
 
 

 
 
01.8-417/1 F2
 
 

 
             

 

       
 

 
 
Six burner bores of different diameter are in place in pre-chamber lower half (burner neck) at different levels and angle positions.
The firing duct (H) has a diameter of 8 mm, the burner neck (J) of 16 mm.
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H
Firing (
iuct
8
mm
dia
 
 
J
Burner
neck
16
mm
dia
 
 
K
Burner
bore
2
mm
dia
 
 
L
Burner
bore
3.5
mm
dia
 
 
M
Burner
bore
2.5
mm
dia
 
 
N
Burner
bore
3.2
mm
dia
 
 
0
Bore for glow plug
9
mm
dia
 
               
 
 

 
 
In addition, the pre-chamber bottom is of spherical shape.
The spherical shape provides uniform wall thickness in range of burner bores.
 
 

 
 
Removal
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1 Disconnect regulating linkage to remove cylinder head cover. Pull out locking eye of longitudinal regulating shaft (arrow).
On models 116.120 and 123, pull longitudinal regulating shaft out of rubber mount in forward direction and remove in rearward direction.
 
 
Model 116.120
 
 

 
 
On model 126.120, pull longitudinal regulating shaft out of guide lever in rearward direction and remove in forward direction.
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Model 123
 
 

 
 
01.8—417/2 F2
 
 

 
       

 

       
 

 
 
On models 123 with automatic transmission 722.303 (W4A040) and 126.120, pull off central plug for vacuum lines (71) or vacuum lines. Disconnect bowden wire, compress black plastic clip (arrow) and pull bowden wire out of holder in rearward direction.
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Model 126.120
 
 

 
 
2   Remove injection lines.
3   Pull fuel return hoses from injection nozzles.
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4 Unscrew complete nozzle holder by means of socket (27 mm).
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01.8-417/3 F2
 
 

 
       

 

       
 

 
 
5 Unscrew rod-type glow plugs (81).
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46     Cylinder head gasket
50     Threaded ring
51     Pre-chamber
52     Sealing ring
53     Nozzle reed
80     Nozzle holder
81      Rod-type glow plug
 
 

 
 
6 Unscrew threaded ring (50) by means of socket wrench.
For this purpose, screw insert (03) into threaded ring, place sleeve (02) into grooves of threaded ring (arrows) and tighten with nut (01).
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03 Screw insert
 
 

 
 
Sleeve (02) should be seated in grooves tight enough to prevent slipping out of grooves when the threaded ring is released.
Position wrench against hex. head of sleeve (02) and unscrew threaded ring.
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01   Nut
02   Sleeve
 
 

 
 
01.8-417/4 F2
 
 

 
       

 

         
 

 
 
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7 Pull-out pre-chamber by means of puller. Screw spindle (01) into pre-chamber. Place bell-shaped member (03) on cylinder head. The contact surface of the bell-shaped member is provided with 2 lugs. One lug each should be seated in hex. or double hex. socket of cylinder head bolt adjacent to pre-chamber. Pull-out pre-chamber by rotating nut (02) with an open-end wrench.
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01    Spindle
02    Nut
03    Bell
 
 

 
 
8 Remove sealing ring (arrow) from cylinder head.
 
 

 
 
9 Cover bore in cylinder head.
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Installation
 
 

 
 
Note: If the removed pre-chambers are installed again, check for perfect condition.
Ball pin should not be burnt or scaled.
In addition, if burner tops are scorched or if pre-chamber lower half shows cracks, remove boost air pipe and check inside for traces of oil.
 
 

 
 
01.8-417/5 F2
 
 

 
         

 

       
 

 
 
If oil-moist spots are found, check diaphragm of vacuum pump on engine 617.950 (@)up to 1979 for cracks and other damage or renew vacuum control unit on injection pump of all engines.
The faulty component is identified by means of the vacuum lines (blackened by oil).
 
 

 
 
10 Place new sealing ring (52) into cylinder head. Use original sealing ring of specified thickness and shape only, so that the required distance (c) of 7.8—8.4 mm between pre-chamber and cylinder head is maintained.
Note: If a cylinder head has been faced at parting surface, add thicker sealing rings (52) between cylinder head and pre-chamber when installing pre-chambers.
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The following sealing rings are available:
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Thickness
Part No.
 
 
1.9-2.1 (standard)
61501700 60
 
 
2.2-2.4
615 017 01 60
 
 
2.5-2.7
61501702 60
 
 
2.8-3.0
615 017 03 60
 
       
 
 

 
 
11 Screw spindle (01) of puller into pre-chamber (illustration item 7). Position pre-chamber in such a manner that the lug faces recess in cylinder head (arrows).
Insert pre-chamber by means of light blows with a plastic hammer against spindle. Pull bell-shaped mem­ber (03) with one hand in upward direction and hold in place (illustration item 7).
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01.8-417/6 F2
 
 

 
       

 

       
 

 
 
12    Lubricate threaded ring (50) and tighten to specified torque of 150—180 Nm by means of pertinent socket wrench.
13   Screw-in pencil element glow plugs and connect.
14    Insert new nozzle plate (53 Fig. item 5). The resilient nozzle plate can be installed on all engines.
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53 Nozzle plate
80     Nozzle holder
81     Pencil element glow plug
 
 

 
 
1073-8020/1
 
 

 
 
15   Completely screw-in nozzle holder and tighten to 70-80 Nm.
16    Install injection lines.
17    Plug fuel return hoses to injection nozzles.
18    Mount cylinder head cover.
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01.8-417/7 F2