General information
1. To make sure that the high pressure fuel pump delivers fuel to each cylinder at the right time during the engine's operating cycle, check and, if necessary, adjust the fuel injection timing. This check should always be carried out after the fuel pump or any associated mast components have been dismantled.
2. There is an inspection hole on the high-pressure fuel pump housing, which is closed with a metal threaded plug in working condition. The start of fuel injection into cylinder No. 1 occurs at the moment when the protrusion on the regulator rotor inside the fuel pump is located opposite the inspection hole.
3. When the protrusion is exactly aligned with the center of the hole, the position of the crankshaft can be determined using the pointer on the camshaft timing chain case and the scale on the crankshaft damper. The angle of rotation of the crankshaft determined in this position provides an indirect determination of the moment of fuel injection.
4. The measurement is best done electronically, using a sensor screwed into the inspection hole of the fuel pump. But, since such equipment is only available to Mercedes-Benz dealers and Bosch diesel fuel equipment specialists, we describe an alternative method. However, it should be noted that this method provides only an approximate setting in order to start the engine - at the earliest opportunity, the car should be tested by specialists in order to obtain accurate data.
Examination
5. Disconnect the negative battery terminal..
6. According to chapter 3 Remove the radiator fan and its shroud.
7. Turn away a cap sideways on the case of the fuel pump. Be prepared for a possible leakage of fuel and lay a piece of rag that absorbs fuel well near the plug hole.
8. Using a small mirror, inspect the edge of the fuel pump rotor through the inspection hole.
9. Using a thorium wrench, use the pulley/damper-to-hub bolt to rotate the crankshaft in the direction of its normal rotation so that the lug on the governor rotor is exactly aligned with the center of the inspection hole (see fig. 7.24).
10. Without allowing further cranking of the engine, determine the angle of rotation of the crankshaft using the pointer on the camshaft timing chain cover and the scale on the crankshaft damper (see fig. 7.8).
11. Compare the obtained value with the one indicated in the paragraph "Technical data" and, if required, adjust. Replace the inspection hole plug and tighten to the correct torque.
Adjustment
12. In accordance with the previous subsection. turn the crankshaft by hand until it reaches the position indicated in paragraph Technical data" nominal value of the fuel injection moment.
13. Loosen the three bolts securing the fuel pump to the support flange. Similarly, loosen the bolt securing the back of the pump to the support bracket (contact for details paragraph 7).
14. Turn out a cap sideways on the case of the fuel pump. Be prepared for possible fuel leakage and lay a piece of rag that absorbs fuel well near the plug hole.
15. Using a small mirror, inspect the edge of the fuel pump rotor through the inspection hole. Using a thorium wrench, use the pulley/damper-to-hub bolt to turn the crankshaft in the direction of normal rotation. Turn the fuel cut-in torque adjustment screw until the lug on the regulator rotor is exactly aligned with the center of the inspection hole (see fig. 9.15).
Pic. 9.15. Screw for adjusting the moment of switching on the fuel supply (shown with an asterisk) on injection pump
Attention: Turn the adjusting screw to the right if the fuel cut-in time is lagging: turn the screw to the left if the fuel cut-in time is ahead of the nominal value.
18. When you achieve alignment, tighten the front and rear fuel pump mounting bolts to the recommended torque.
17. Replace the inspection hole plug and tighten to the correct torque.
18. Should be considered. that this method provides only the preliminary adjustment necessary to start the engine - the engine should be tested and adjusted at the earliest opportunity by Mercedes-Benz dealers or Bosch specialists.