This test is used to check if there is an internal fuel leak in the feeder or injectors. If there is an internal leak, this will result in an increased fuel flow from the cylinder head return line. Before the test is carried out, it must be ensured that there is no external fuel leak.
During testing, the fuel system is under high pressure; therefore it is essential to wear protective goggles and maintain a safe distance from the engine.
During the test, error codes can occur on other systems, and must be erased after the test.
Special tools, ordered from a DAF dealer, must be used to carry out the test.
Special tool: DAF no. 1453195
Special tool: DAF no. 1453198
The first step is to check whether there is an internal leak. The fuel flow from the return line must not exceed 200 ml/min.
If the quantity of fuel exceeds this limit, it must be determined which cylinder has an internal leak.
Once the suspected internally-leaking cylinder has been plugged, the amount of fuel from the return line will reduce.
The example shows that cylinder 2 has an internal leak.
Example |
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Result |
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Plugged cylinder | | | | |
Fuel quantity ml/min | | | | |
Accelerator pedal let up.
The engine must idle for at least 1 minute before the test is started.
Check using the test whether there is an internal fuel leak.
Tilt the cab according to the manufacturer's instructions.
Remove the return line from the cylinder head.
Fit the test line with banjo screws and gaskets on the cylinder head (Part of special tool DAF no. 1453195).
Plug the return line, use the accompanying banjo screws with gaskets, and fit the sealing cap (Part of special tool DAF no. 1453195).
Place the free end from the test line into a container of at least 1000 ml.
After the test has been carried out, check the amount of fuel from the return line.
If the amount of fuel is less than 200 ml/min, there is no internal leak. The test is then complete, and the test equipment should be removed and the return line fitted at the correct tightening torque.
If the amount of fuel is greater than 200 ml/min, there is an internal leak, and it must be located.
Remove the injection line from the rail outlet on cylinder 1.
Plug the rail outlet for cylinder 1 with special tool DAF no. 1453198. Tightening torque 30 NM.
Check how many ml/min are coming from the return line.
Remove special tool DAF no. 1453198, and fit the injector line to the rail outlet for cylinder 1.
Repeat the test procedure for the other cylinders, and note all the values.
Once the leaking cylinder has been plugged, the amount of fuel from the return line will decrease.
