Oil Filter

The oil filter removes most of the impurities that have been picked up by the oil, as it circulates through the engine. Designed to be replaced readily, the filter is mounted in an accessible location outside the engine.

There are two basic filter element configurations—the cartridge type and spin-on type.

1. The cartridge-type element (fig. 6-24) fits into a permanent metal container. Oil is pumped under pressure into the container where it passes from the outside of the filter element to the center. From here, the oil exits the container. The element is changed easily by removing the cover from the container.
2. The spin-on filter (fig. 6-24) is completely self-contained, consisting of an integral metal container and filter element. Oil is pumped into the container on the outside of the filter element. The oil then passes through the filter medium to the center of the element where it exits the container. This type of filter is screwed onto its base and is removed by spinning it off.

The elements themselves may be either metallic or nonmetallic. Cotton waste or resin-treated paper is the most popular filter mediums. They are held in place by sandwiching them between two perforated metal sheets. Some heavy-duty applications use layers of metal that are thinly spaced apart. Foreign matter is strained out, as the oil passes between the metal layers.

There are two filter configurations. These are the full-flow system and the bypass system. Operations of each system is as follows:

1. The full-flow system (fig. 6-25) is the most oil filter to allow the oil to circulate through common. All oil in a full-flow system is the system without passing through the element circulated through the filter before it reaches the in the event that it becomes clogged. This engine. When a full-flow system is used, it is prevents the oil supply from being cut off to the necessary to incorporate a bypass valve in the engine.
2. The bypass system (fig. 6-25) diverts only a small quantity of oil each time it is circulated and returns it directly to the oil pan after it is filtered. This type of system does not filter the oil before it is sent to the engine. The oil from the main oil gallery enters the filter and flows through the filter element. It then passes into the collector in the center of the filter. The filtered oil then flows out a restricted outlet preventing the loss of pressure. The oil then returns directly to the oil pan.

Figure 6-24.—Oil filters.