Fuel Injection Nozzles - Updated
REF. NO. 07.1/27 aTO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS
DATE: February, 1983 (supersedes 07.1/27) REF.NO. 07.1/27 a
SUBJECT:
TEST AND REPAIR INSTRUCTIONS FOR CHIP FUEL INJECTION
NOZZLES ON ALL MODELS EQUIPPED WITH DIESEL ENGINES
NOTE:
This issue revises the chassis end number of model 240 D, (deletes model 300 D and adds Robert Bosch as a nozzle manufacturer.
Beginning with the chassis numbers, new nozzles with a short pintle and 0.2 mm diameter chip hole have been installed.
The factory installed nozzle assemblies are marked with a blue paint dot on the holder for naturally aspirated engines and a brown paint dot for all turbo models. Robert Bosch (R.B.) remanufactured injection nozzle assemblies, however, do not have a paint code, but are fitted with a sleeve of heat shrink tubing around the upper part of the nozzle assembly that has only the R.B. part number.
Robert Bosch Number on the Injection Nozzle Holder
A heat shrink tape on the upper port of the nozzle holder carries the following Bosch designation for
a) naturally aspirated engines: 0432 217 093 Rev.
b) turbocharged engines: 0432 217 101 Rev.
The original factory nozzle assemblies or remanufactured nozzle assemblies are available from our Parts Depots and must be used for any repairs performed under warranty. With our Service Information MBNA 07.1/6 of February 1982 and Warranty Policy Letter No. 26 of September 1981, it was mandatory to exchange all nozzle assemblies in case of knock, partial load knock with hot engine or extremely rough idle.
This instruction is no longer valid since testing of returned nozzle assemblies indicated no identifiable defect in most cases and it is now clear that not every complaint related to a knocking engine can be resolved by simply changing the complete set of nozzle assemblies as recommended at that time.
We therefore ask you to proceed in cases of complaints such as partial load knocking and intermittent pinging at operating temperature as outlined in the following paragraphs.
1. Verify the complaint with the customer. If slight or occasional knock has been reported or knocking occurs during cold start only, experience has shown that the use of a different brand of diesel fuel will often cure the problem. Please keep in mind that knocking of a cold diesel engine is not a sign of malfunction and not harmful to the engine. Perform all verification tests with the engine at operating temperature.
2. If the knocking problem still persists after operating on one or more tanks of different fuel, the nozzle assemblies must be removed.
3.1 If the knocking nozzle assembly set is of the older design with 0.15 mm diameter chip hole (identification on the nozzle holder: yellow paint dot for naturally aspirated engines, green paint dot for turbo engines), the whole set should be replaced remanufactured nozzle assemblies of the newer design.
3.2 If the nozzle assemblies in question are already of the new 0.20 mm chip hole type (identification: blue paint dot for naturally aspirated engines, brown paint dot for turbo engines), all nozzle assemblies must be tested and only the defective ones should be exchanged.
4. For testing of injection nozzle assemblies, proceed as follows:
Use the nozzle cleaning needle, tool number 900 589 00 68 05, 0.18 mm diameter from your cleaning kit and check the longitudinal 0.20 mm diameter hole in the nozzle needle for any obstructions. If the needle cannot be inserted, the nozzle assembly has to be replaced. If the chip hole is open, proceed with the testing of the nozzle assembly as outlined in microfiche engines 615, 616, 617.91, Combustion I and Engine 617.95 Turbo Diesel Combustion I, Job No. 07.1 - 135.
When performing this test, use the Bosch Tester (special tool number 900 589 14 27 00; Bosch number 1 681 200 502) with the special adapter for testing chip nozzles, tool number 902 589 00 90 60. The adapter consists of a two position valve pre-assembled to a fuel line. This assembly is installed in place of the standard test line. To test the chip hole in the nozzle turn valve handle into horizontal position.
NOTE:
With valve handle in horizontal position the flow diameter is reduced to 0.4 mm, providing a clearer view of the center spray pattern, by limiting the nozzle needle lift.
Turn valve into vertical position to test total spray pattern, nozzle chatter or for leakage.
NOTE:
Do not disassemble nozzle assemblies for any of these tests.
5. In case of severe engine vibration on turbocharged engines which can be observed when the hot engine is idling in a rocking motion, it is mandatory to first perform the adjustment of the factory installed - BUT NOT ADJUSTED - vibration dampener on the rear cover of the governor housing. The procedure is outlined in detail in Service Information 07.1/21 Of July 1980 (see also SMF Engine 617.95 Turbo diesel Combustion I 07.1.8 Job 200).
NOTE:
If vibration dampener adjustment does not bring engine idle to normal, test nozzle assemblies as outlined in step 3.2.
8. Only after 2 or 3 repeat nozzle assembly failures, or if performance complaints remain uncorrected, should the fuel injection pump timing be checked and, if necessary, corrected. In that case, the injection pump timing must be set at 24~ +1~ BTDC. Please confirm correction of the timing by application of a permanent white paint dot on injection line No. 1, near the injection pump.
7. All nozzle assemblies and injection pumps replaced under warranty and returned to MBNA will be tested in order to verify the validity of the complaint. Nozzle assemblies and pumps which were exchanged after the issue of this Service Information and found not to be defective will be returned to the responsible dealership.
8. Service Information MBT 07.1/8 of August 1979, Service Information MBNA 07.1/6 of February 1982 and Warranty Policy Letter No. 26 of September 1981 are invalid as of the publication of this bulletin and should be removed from the respective binder.
Part Information