PUMP GP-GEAR 3412860 - Caterpillar

All 3500 Series EnginesCorrect installation of the fuel lines and elbows on 3500 Series Engines is important. Elbows and fuel lines that are not installed correctly can cause damage to the aluminum threads in the fuel manifold or may result in a cracked or broken elbow.
Damage to the threads in the fuel manifold can be the result of any of these conditions:
1. Too much torque is used when the elbow is tightened. If there is a leak between the elbow and the manifold, do not try to tighten the elbow. Instead, remove the elbow and inspect the threads of the manifold and elbow for damage. Also check the condition of the O-ring seal. Make a replacement of the manifold, elbow or O-ring seal if necessary.2. The elbow is turned before the locknut is loosened. The locknut must always be loosened before the elbow is turned.3. There is paint on the threads of the elbow or manifold.4. The elbow or fuel line is used as a step or handle to get on top of the engine.A crack or a broken elbow can be caused by any of these five conditions:
1. The elbow is not in the correct position when the fuel line nut is tightened. When the fuel line is connected to the elbow, make sure the locknut on the elbow is loose. This will permit movement of the elbow so that it will be in the correct alignment with the fuel line. Tighten the lower fuel line nut. Make sure the fuel line is still in the correct alignment with the elbow. The fuel line is not in the correct alignment if it is difficult to turn the upper fuel line nut when it is tightened. Use a wrench to hold the elbow in the correct position while the upper fuel line nut is tightened. Tighten the locknut on the elbow.2. A wrench is not used to hold the elbow in the correct position when the upper fuel line nut is tightened.3. There is paint on the threads of the elbow.4. Too much torque is used to tighten the upper fuel line nut.5. The elbow or fuel line is used as a step or handle to get on top of the engine.
Fuel manifold and fuel lines on 3500 Series Engines.