Operation and Maintenance Manual of WP13C Series Diesel Engines
Weichai Power Pursuit of Excellence
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3.2 Internal high pressure connecting
The high pressure fuel reaches the fuel injector through the fuel inlet joint inside the cylinder head. When
carrying out proper high pressure sealing of a standard fuel inlet joint, the required minimum pre-pressing
force is 12kN and maximally 22kN is allowed. If the force is too high, it may lead to overload of fuel inlet
joint and cause leakage.
When mounting the fuel inlet joint, please apply lubricating oil on the O-ring and thread pair. Apply
recommended mineral oil on the threads and shaft shoulder. The oil used must be suitable for material of
O-ring. If surface lubrication of O-ring and threads is already carried out, oiling is not required.
Due to lateral sealing force of fuel inlet joint, random mounting will cause improper stress (lateral force
generated by fuel inlet joint will bend the fuel injector) on the fuel injector, and this is very dangerous.
Learned from previous practices, tightening in 5 steps is most suitable to minimize the stress distortion of
fuel injector.
The recommended 5 steps for tightening the fuel inlet joint are as follows:
(1) Insert the fuel injector into the cylinder head. Make sure that the fuel injector is properly positioned
and contact with the seal rings correctly, tighten the clamping bolts of fuel injector by torque of 3Nm;
(2) Loosen the clamping bolts of fuel injector until the axial force of fuel injector is 0 and make sure that
the fuel injector is correctly positioned in the cylinder head.
(3) Pre-tighten the high pressure fuel inlet joint (nut) by the torque of( 15-20)Nm. This force is essential
for aligning the fuel injector with the fuel hole;
(4) Tighten the clamping bolts of fuel injector by the torque of 8Nm+90°;
(5) Tighten the high pressure fuel inlet joint (nut) by the torque of (50-55) Nm.
