Pre-chamber - Reworking Seating Surfaces
01/13, 58/66
To: OUR MERCEDES-BENZ PASSENGER CAR DEALERS 1988
SUBJECT:
PRE-CHAMBER SEATING SURFACES ENGINES 601, 602, 603
If a pre-chamber shows evidence of leaking (i.e. blow-by or gas bubbles) after having been removed and reinstalled.
first proceed as follows:
With compressed air, blow area around pre-chamber dry to avoid gas bubbles from spilled evaporating diesel fuel. Run engine for at least 15 minutes at 2500 - 3000 rpm. This will seal minute surface irregularities between the chamber and Cylinder head.
If leaks persist, rework the seating surface with special tool 601 589 00 66 00 (Figure 1). This procedure is necessary if the pre-chamber seat is damaged or leaking and can be performed with the Cylinder head installed or removed.
If the Cylinder head remains installed, then the pre-chamber seating surface may be reworked only once. It is absolutely essential to observe the specified pre-chamber projection of 7.6-8.1 mm (Dension C, Figure 2) as it provides the required Clearance between the pre-chamber and the piston Crown with
the Piston at TDC. Therefore, spacer washer must be inserted on re-worked seating surfaces. These are available in thicknesses of 0.3, 0.6 and 1mm
Figure 2:
Figure 2
If a spacer washer has already been installed or the cylinder head has been marked (see Figure 6), then the cylinder head must be removed and demension C" must be measured if further reworking of a pre-chamber seating surface is required.
Procedure With Cylinder Head installed
1. Remove pre-chamber (see Repair Instructions, Service Microfiche Group 01, Job No. 417).
2. Close pre-chamber bore (with a rag for example) to prevent any metal shavings from falling into the combustion chamber.
3. Unscrew protective sleeve from end mill (07, Figure 1)
4. Screw end mill into pre-chamber bore to be reworked until it is seated.(figure 4)
5. Using a depth gauge, measure and record dimension "X" between upper edge of end mill shaft (01) and sleeve (02, Figure 4).
6. Place handle on end mill. Without lifting it, turn end mill approximately 5 turns clockwise using light pressure (Figure 5).
7. Measure demension "X" again. The difference between the first and second measurement indicates the amount of material removed.
Example: "X" prior to reworking = 25.7 mm
"X" after reworking = 25.5 mm
Material removed = 0.2 mm
In this case, a 0.3 mm thick spacer washer would be installed
The spacer washer selected must be at least 0.1 mm thicker than the material removed from the seal surface.
8. unscrew end mill and remove all metal shavings.
Note:
If the seating surface is not completely even, then the end mill must be reinserted and the seating surface must be reworked again. Afterwards, repeat measurement in step 5.
9. Remove rag fram pre-chamber bore and crank engine with starter. This will eject any possible metal shavings from the combustion chamber.
10. Select the correct size spacer washer and insert it.
Figure 6:
11. Using a center punch, mark the cylinder head above each pre-chamber that has been reworked (Figure 6)
12. Reinstall pre-chamber.
Note:
the procedure with the cylinder head removed is the same with exception of steps 5 and 7. instead of steps 5 and 7, the Pre-chamber projection (demention c, figure 2) must be measured.
Parts Information
Part name part number
Spacer washer 0.3 mm 601 017 04 60
0.6 mm 601 017 02 60
1.0 mm 601 017 03 60
Time Allowance
02-0111 Pre-chamber Seat, Rework 0.8 hrs. 42/43/46/57/81/87
02-0112 Pre-chamber Seat, Rework 00.2 hrs. 42/43/46/57/81/87
(Cylinder head removed)
Damage Code
01221 89 Pre-chamber, rework seat in cylinder head