PIN 4I9664 - Caterpillar

Caterpillar Diesel EnginesFuel injection lines are a small but very important part of a diesel engine. These lines operate under very high pressures, and careful, correct procedures must be used during installation and maintenance work to prevent damage and keep out dirt. A line failure caused by damage or wrong installation is a problem for the customer, and can possibly cause a fire. Dirt in a line can flow into the injection valve and cause engine damage. To be sure of good performance and maximum service life from fuel injection lines, check these items of caution:
1. Never bend an injection line, or install a line which has been bent by accident. If clearance is needed for other work, remove the line; do not bend it out of the way. In addition to the possible development of cracks, a bent fuel injection line can have a restriction which increases line pressure and can damage the fuel injection pump. It can also have an effect on engine performance. For reference, see the troubleshooting section of the service manual.2. Keep the fuel injection lines and connections clean. Be sure to install caps and covers any time a line is removed or disconnected. Dirt in the fuel injection valve (nozzle) can damage the engine.3. Be sure the connection surfaces which must seal the line connections have protection. Any damage to these surfaces will permit fuel leaks.4. During service work, do not hit the lines with wrenches or other tools. Small cuts or scratches on the surface of a line can cause stress concentrations and possible failure.5. During fuel line installation, use the correct torque to tighten connections. Too much torque can make the hole smaller in the tapered end, or cause other damage. A smaller hole in the end of the line can cause a restriction of fuel flow. Any other damage to the connection can cause fuel leakage, and/or make it necessary to install new parts. Correct torque values are shown in the service manual specifications.6. When fuel injection lines are installed, be sure the clamps and dampers are correctly installed. The correct location and installation of the fuel line clamps and dampers is necessary to prevent vibration of the lines. Too much vibration is a sure cause of failure.7. Make sure the fuel injection lines have enough clearance to prevent contact with any other engine component. In contact with any other engine parts, normal vibration of the engine will cause wear to the injection line. The result of this wear will be fuel leakage or a broken injection line.It is important to remember that the fuel injection lines must operate under very high pressures and stresses, and are part of the precision injection system. For this reason, small amounts of damage can cause cracks or broken lines. Primary causes of fuel injection line failures have been damage when the lines were bent, and vibration when clamps and dampers were not correctly installed. With the use of careful, correct procedures during