si0716w0023a

Service Information: Damage to fuel injection system in combination with poor fuel grade

Type si · topic 07.16 · version 0100 · 2019-11-22

Applies to: Engine 470.9, 471.9, 473.9 in model 963, 964 Engine 934.9, 936.9 in model 967 Engine 936.9 in model 956, 963, 964

Where it sits

Function group 1 Engine › 07 Mixture formation › 07.16 Diesel injection system common rail — Series 470 (models 9**) · Series 471 (models 9**) · Series 934 (models 9**) · Series 936 (models 9**) · Series 956 · Series 963 · Series 964 · Series 967

EinPAS 15 Engine › 15.45 Engine management › 15.45.1 Basic information — Series 470 (models 9**) · Series 471 (models 9**) · Series 934 (models 9**) · Series 936 (models 9**) · Series 956 · Series 963 · Series 964 · Series 967

EinPAS 45 Data/information › 45.20 Information/measures › 45.20.20 Service information — Series 470 (models 9**) · Series 471 (models 9**) · Series 934 (models 9**) · Series 936 (models 9**) · Series 956 · Series 963 · Series 964 · Series 967

Also applies to engines/gearboxes: 473 9**

SI07.16-W-0023A

Service Information: Damage to fuel injection system in combination with poor fuel grade

11.11.2019

Engine

470.9, 471.9, 473.9 in model 963, 964

Engine

934.9, 936.9 in model 967

Engine

936.9 in model 956, 963, 964

Service Information: Damage to fuel injection system in combination with poor fuel grade

Float needle sealing seat on injector

A

Erosion wear (partial)

B

Erosion wear (extensive)

W07.16-A019-81

This service information contains the results of the latest investigations and is also suitable for handing over to customers.

In some parts of Europe, there is currently a problem with the fuel quality of imported fuels. Currently, regions in northern Germany as well as the south and south-east of the United Kingdom are particularly affected. Measurements show that some of these imported fuels are loaded with a very high number of hard, tiny particles (1-2 µm). These lie above both historical values as well as values for current products from other refineries in Europe. Despite the best vehicle and engine-side fuel filters, these small particles cannot be completely separated, even with the most modern filter technologies, and can therefore cause damage to components of common rail diesel injection systems.

The small particles in the fuel generate erosive seat wear (A, B) on the valves of common rail injectors. This seat erosion leads to internal leakage of these valves. As a result, there is too-fast reduction in rail pressure when the engine is switched off. This is detected by the On-Board Diagnostics and reported as a fault (MCM fault code 35040E, yellow warning message). If this fault appears, it must be processed by means of the guided troubleshooting process in XENTRY and, depending on the result, the affected injectors must be replaced.

Mercedes-Benz Trucks is working closely together with reputable fuel and mineral oil companies in order to once again improve the quality of fuel products in the affected regions and sales areas. Moreover, a cause study of the particle contamination and the submission of recommendations for alteration to the currently valid EN590 Diesel Specification have been commissioned by the CEN (European Committee for Standardization) with all due haste. Based on the CEN's empirical values, fuel should at least meet the requirement of ISO  4406 code 20 (Size:  4  µ particles; number <  10,000/ml) in order to be suitable in the long-term for use in modern common rail diesel injection systems. Furthermore, these limit values are currently being incorporated into the EN590 Diesel Specification.

In the event of complaints concerning the MCM fault code 35040E, we would ask you to inform your customers about the causal fuel quality and recommend that they change their refueling behavior.