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Re-use of High Pressure Injectors

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In this article you will find out about the importance of renewing High Pressure Pipes.

Diagnostics & Test Equipment How to 2 min read

Make	Model	System
Audi	All Common Rail applications	Diesel Systems
Alfa Romeo	All Common Rail applications	Diesel Systems
BMW	All Common Rail applications	Diesel Systems
Citroen	All Common Rail applications	Diesel Systems
Dacia	All Common Rail applications	Diesel Systems
Fiat	All Common Rail applications	Diesel Systems
Ford	All Common Rail applications	Diesel Systems
Honda	All Common Rail applications	Diesel Systems
Hyundai	All Common Rail applications	Diesel Systems
Jaguar	All Common Rail applications	Diesel Systems
Kia	All Common Rail applications	Diesel Systems
Land Rover	All Common Rail applications	Diesel Systems
Nissan	All Common Rail applications	Diesel Systems
Peugeot	All Common Rail applications	Diesel Systems
Skoda	All Common Rail applications	Diesel Systems
Suzuki	All Common Rail applications	Diesel Systems
Ssangyong	All Common Rail applications	Diesel Systems
Toyota	All Common Rail applications	Diesel Systems
Vauxhall	All Common Rail applications	Diesel Systems
VW	All Common Rail applications	Diesel Systems
Volvo	All Common Rail applications	Diesel Systems

Importance of Renewing High Pressure Pipes

It is important to consider renewing the high pressure pipes on Common Rail systems after any intervention on the high pressure system. This is for a number of reasons:

1. To prevent leakage.

When a pipe gland is tightened on first application, the surface of the sealing dome is deformed to provide a tight seal between the pipe and injector / rail / pump components. If the pipe is subsequently re-used the pipe further deforms but is also work hardened so a tight seal is more difficult to achieve.

2. To prevent dirt or swarf ingress.

When a screw thread is tightened, minute particles of swarf are generated and are encased within the grooves of the screw thread. When the thread is released these particles are free and subsequent re-use may dislodge these particles and contaminate the component being worked on.

3. Hydraulic performance.

When the pipe gland nut is tightened the dome of the pipe deforms. Subsequent re-use will continue to deform the sealing edge as described above. However, the other consideration is that the bore of the pipe deforms and can cause restriction of flow, which in turn affects performance of the fuel system and also the engine.

Figure 1

The pipe in figure 1 shows a cross-section of a pipe after single use and the bore is unrestricted.

Figure 2

Figure 2, however, shows a pipe after multiple uses and clearly the pipe diameter is restricted.

Safety First

When fitting pipes after repair it is imperative that the correct torque is applied to the gland nut. Exceeding the torque risks the scenario in figure 2 as the pipe will excessively deform, but also not achieving the correct torque will risk high pressure leaks.

In all cases respect health and safety when working on high pressure systems and ensure the operatives are correctly trained in the service routines for Common Rail systems.

Further Information

Read the relevant Common Rail workshop manual on Direct Evolution:

Part Number	Description
DDGX200A	Principals of CR Operation

Tools & Equipment

Part Number	Description	Operation
DS150	Diagnostic tool	Check for pressure in system
YDT339	HP pipe spanner (19 mm long)	Correct removal of HP pipe
YDT512	HP pipe spanner (19 mm long)	Correct removal of HP pipe
YDT496	HP pipe spanner (17 mm short)	Correct removal of HP pipe

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