SEAL-O-RING 1075769 - Caterpillar

3500 Series EnginesThe engine user must be aware of the damage water contaminated fuel can cause in the engine's fuel injectors and try to keep water out of the fuel system. The fuel injectors rely on fuel for lubrication. Water does not provide the required lubrication for the injector's moving internal components. Water can cause excessive wear on the components.
Water in the fuel can also cause some of the internal components of the injector to rust. The combination of rust particles and poor lubrication produced by water in the fuel can cause the fuel injector to seize.
Normally, water contamination of the fuel can be controlled by good maintenance practices. Some water vapor in the air is absorbed by the fuel in the fuel tank. Water vapor can also condense on the inside walls of the fuel tank and become mixed with the fuel. These sources of water in the fuel are normal and expected. Periodic draining of fluid from the bottom of the fuel tank will remove excess water. The frequency of draining should depend on factors such as ambient temperature, relative humidity, application and number of hours the engine is operated. Monitoring the amount of water that is drained will help determine the frequency of the checks.
In some cases, this type of maintenance is not sufficient. A batch of fuel from a fuel supplier may contain an excessive amount of water, or a leak in an underground tank or a tank that is below water level can result in a large volume water in the tank. Marine applications are quite prone to this situation, since ship fuel tanks and fuel supply barges usually are below (or partially) below water level.
In applications where there is a significant risk of water contamination, a water separator should be installed in the fuel system. The largest water separator offered by Caterpillar is the 8N940 Water Separator Group. The 8N940 Water Separator Group is capable of handling fuel flow requirements of high speed 3500 Series Engines up to 1600 rpm and low speed 3500 Series Engines up to 1050 rpm. For higher speed applications, either two 8N940 Water Separator Groups connected in parallel or a larger aftermarket water separator would be required.