Engine timing, valves,  OM617

Inspection and adjustment of camshaft timing

 

 

05—215 Inspection and adjustment of camshaft timing

 

Timing at 2 mm valve lift

 

Engine
Camshaft code number1)
Intake valve opens after TDC
closes after BDC
Exhaust valve opens before BDC
closes before TDC
617.9502)
00 084)
with new timing chain
11.5°
13.5°
21°
19°
with used timing chain (from approx
20 000 km)

 

13.5°
15.5°
19°
17°
617.9503) 617.951 617.952
054)
with new timing chain
15°
27°
16°
with used timing chain (from approx
20 000 km)

 

11°
17°
25°
14°

 

M Camshaft code number is punched into rear end of camshaft.
2)  ^r\ up to model year 1979.
3)  ^3″ model year 1980.
4)  Camshaft made of chilled cast iron.

 

Valve clearance
with engine cold (approx. 20 °C)
with engine warm (60 °C ± 15 °C)

 

Intake 0.101)
0.151)

 

Exhaust 0.35
0.40

 

l) 0.05 mm higher during lasting outside temperatures below —20 °C. Tightening torques

 

Nm
Nuts for cylinder head cover

 

15
Necked-down screw for camshaft sprocket

 

80
Closing plug for chain tensioner

 

90
Special tools

 

 

 

Valve adjusting wrench 14 mm (2 each)
om617 - 0147-1.jpg
615 589 00 01 00
Holding wrench for valve spring retainer
615 589 00 03 00
Slip gage holder, red
617 589 00 40 00
Slip gage blades
0.10 mm thick 0.15 mm thick
617 589 00 23 00 617 589 01 23 00

 

05.8-215/1 F2

 

 

 

Socket 27 mm, 1/2″ square, for rotating engine
om617 - 0148-1.jpg
001 589 65 09 00

 

Dial gage holder
om617 - 0148-2.jpg
363 589 02 21 00
11004-10150

 

Impact puller for bearing bolt (basic unit)
om617 - 0148-3.jpg
116 589 20 33 00

 

 

om617 - 0148-4.jpg

 

 

 

Note

 

During assembly jobs, alignment of the markings (arrow) in ignition TDC position of 1st cylinder will be sufficient.
In special cases, e.g. during complaints about perfor­mance, check and adjust begin of opening at intake valve of 1st cylinder.
Timing is measured at 2 mm valve lift. For this pur­pose, the valve clearance must be neutralized.
om617 - 0148-5.jpg

 

Checking

 

1    Unscrew pencil element glow plugs.
2    Disconnect regulating linkage to remove cylinder head cover. Pull out locking eye of longitudinal re­gulating shaft (arrow).
om617 - 0148-6.jpg
Model 116.120

 

05.8-215/2 F2

 

 

 

On models 116.120 and 123, pull longitudinal regu­lating shaft out of rubber mount in forward direction and remove in rearward direction.
On model 126.120, pull longitudinal regulating shaft out of guide lever in rearward direction and remove in forward direction.
om617 - 0149-1.jpg
Model 123

 

On models 123 with automatic transmission 722.303 (W 4 A 040) 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.
om617 - 0149-2.jpg
Model 126.120

 

3 Rotate crankshaft with tool combination until cam tip is pointing upwards.
Attention!
Do not rotate engine on fastening screw of camshaft sprocket. Never rotate engine in reverse while measur­ing, since this will result in considerable measuring faults.
om617 - 0149-3.jpg

 

4 Just cancel valve clearance at intake valve of 1st cylinder by screwing up cap nuts (05—210).
om617 - 0149-4.jpg

 

05.8-215/3 F2

 

 

 

5 Screw dial gage holder with threaded sleeve to stud at front right.
om617 - 0150-1.jpg

 

6    Insert dial gage and fasten in such a manner that the feeler pin rests on valve spring retainer at a preload of 3 mm (small needle of dial gage) (arrow).
Turn dial of dial gage until large needle rests on “0”.
Attention!
Feeler pin of dial gage should be seated on valve spring retainer in accurately vertical position.
7    Keep turning crankshaft in direction of rotation of engine until small needle of dial gage has gone back by 2 mm (valve lift) to 1 mm.
In this position, the value on balancing disk should be in agreement with the indicated value “intake valve opens”.
om617 - 0150-2.jpg

 

Adjustment

 

If the timing requires correction, install an offset Woodruff key or, if the chain is excessively elongated, install a new timing chain.

 

Woodruff keys are available in the following steps:

 

Offset
Part
No.

 

for a <
:orrection
mm

 

 

 

of approx.
0.7
621
991
04 67
crankshaft
0.9
621
991
02 67
6 1/2C
1 crankshaft
1.1
621
991
01 67
crankshaft
1.3
621
991
00 67
10°
crankshaft

 

05.8-215/4 F2

 

 

 

An offset by one tooth on camshaft sprocket results in approx. 18° at crankshaft.
An offset of Woodruff keys to the right (in driving direction [A]) results in an earlier begin of opening, and an offset to the left (B) in a later begin of open­ing.
om617 - 0151-1.jpg

 

8 Set engine to ignition TDC of 1st cylinder.
om617 - 0151-2.jpg

 

9 On engines with EGR (usa), remove pipe line be­tween EGR valve and exhaust manifold (arrow). Unscrew shielding plate (10) for this purpose.
om617 - 0151-3.jpg

 

10 Unscrew closing plug of chain tensioner and remove compression spring (05—310).
om617 - 0151-4.jpg

 

05.8-215/5 F2

 

 

 

11 Remove slide rail in cylinder head. Pull out bear­ing bolt by means of impact puller.
om617 - 0152-1.jpg

 

om617 - 0152-2.jpg

 

12 Mark camshaft sprocket and timing chain in relation to each other.
om617 - 0152-3.jpg

 

13 Remove camshaft sprocket.
To loosen necked-down screw of camshaft sprocket, apply counterhold with a screwdriver or steel pin.
om617 - 0152-4.jpg

 

05.8-215/6 F2

 

 

 

14    Place rag under camshaft and remove Woodruff key.
15    Insert selected Woodruff key.
16   Mount camshaft sprocket while paying attention to color marks.
Do not tighten necked-down screw.

 

17    Repeat item 6 and 7.
18   Tighten necked-down screw for fastening cam­shaft sprocket to 80 Nm. For this purpose, apply counterhold to camshaft sprocket by means of a screwdriver or a steel pin.
19    Install slide rail.
om617 - 0153-1.jpg

 

20 Place compression spring into chain tensioner and tighten closing plug to 90 Nm.
om617 - 0153-2.jpg

 

21    Unscrew dial gage holder.
22   Adjust valve clearance at intake valve of 1st cylinder (05-210).
23   On engines with EGR <@), install pipe line be­tween EGR valve and exhaust manifold. Screw on shielding plate.
24    Mount cylinder head cover.
om617 - 0153-3.jpg

 

05.8-215/7 F2