What Is an Oil Filter Bypass Valve, and Why Is It Important?

An airplane’s engine during maintenance.

When you operate machinery, you need dependable, all-metal filters that can remove contaminants and prevent long-term damage to your fluid system. One key component of a high-quality oil filter is a bypass valve. An oil filter’s bypass valve helps avoid destruction to the machine when the filter inevitably gets clogged. This allows the oil to go straight to the engine to prevent starvation.

A jet engine diagram

Unfiltered oil is better than no oil. An oil filter only has so much capacity to clean out impurities. That’s why getting an all-metal filter from Fluid Conditioning Products is essential. Not only do our filters outperform legacy materials, but they have been shown to reduce maintenance and downtime on military helicopters, providing enormous cost savings.

For nearly 80 years, the team at Fluid Conditioning Products has been manufacturing oil filters with high-quality bypass valves that have to endure some of the harshest conditions. You can depend on us to craft a customized, highly efficient filter for your hydraulic, water, and oil filtration needs!

Learn more about how an oil filter’s bypass valve works and why it is necessary to ensure you have a correctly functioning valve in your fluid system. Then request a quote to get one of the best filters on the market.

What Is a Bypass Valve in an Oil Filter?

An oil filter’s bypass valve is a safety measure when the oil filter becomes clogged, or the oil is too thick. It’s also known as a pressure relief valve. Basically, when oil can no longer pass through the filtration medium, the bypass valve opens to allow the oil to flow directly to the engine. Without a bypass valve, the oil will not make it to the engine when the filter is clogged, causing extensive system damage or even failure.

When an oil filter works properly, the oil pump sucks the oil from the oil reservoir and cools it through the engine oil cooler. It then passes through a line to the system’s oil filter, purifying the oil. The oil can contain impurities that, if not appropriately filtered, cause damage to your machine. That’s why you must have an all-metal filter from FCP in your fluid system.

Legacy materials like fiberglass or cellulose can shed particles that cause damage to your system and other components downstream. On the other hand, all-metal filters have the highest-level filtration efficiency—often greater than 99%—and can reduce your maintenance requirements by as much as 10x. Get started today by requesting a quote for your all-metal filter.

What Happens if the Oil Filter’s Bypass Valve Is Open?

When the bypass valve is open in an oil filter, the oil can pass through a center tube that goes straight to the engine to prevent starvation and damage. It allows the oil to “bypass” the filter so that you can continue operating your machine. However, if the bypass valve is open, it indicates that you may need to change or clean your filter because unfiltered oil passing through the entire system, which can also cause issues.

FCP can equip our all-metal filters with differential pressure indicators, which provide a visual reading of the pressure on the inlet versus the outlet side of the oil filter. A pop-up button signals when the filter is clogged, with a more complex system using an electrical switch that illuminates a light. This system also signifies that your bypass valve will likely open so your oil can reach the engine.

It’s essential to regularly change your airplane’s, helicopter’s, or marine system’s oil according to the manufacturer’s recommendations. Continually changing your oil and cleaning your all-metal oil filter helps minimize sludge that may cause the bypass valve to stick. If that happens, the oil pressure drops, causing damage to the fluid system.

Where Is the Bypass Valve Located?

It depends on the type of filter you have. A spin oil filter’s bypass valve is part of the filter itself. Once the filter is clogged, that bypass valve can easily open and allow the oil to flow through to the engine. The bypass valve is part of the filter housing in a cartridge oil filter.

Do I Need a Bypass Valve in My Oil Filter?

Yes, without a bypass valve or with a malfunctioning bypass valve, the pressure in the oil filer would build, causing it to burst and the oil to leak. If the valve opens too soon or too often, contaminated oil will flow into the system, causing damage to the machine itself.

An oil filter’s capacity can only handle so many contaminates before it needs to be changed. Just like the oil in your car or truck at home, your airplane’s, helicopter’s, or submarine’s oil needs to be changed and the oil filter cleaned.

Request a Quote for Your Filtration Needs!

For these reasons, you need to order high-quality all-metal filters from the experts at Fluid Conditioning Products. We carefully calculate the opening pressure required of your oil filter’s bypass valve to ensure it only opens when needed so that your engine gets the filtered oil it needs when it needs it.

While unfiltered oil is better than no oil, you will want to be sure to change the filter and the oil as soon as you notice the differential pressure indicator is popped up. Routine oil changes help ensure that the all-metal filter you ordered from Fluid Conditioning Products can provide the filtration efficiency you expect, significantly reducing your maintenance and providing significant cost savings. Get started today by requesting a quote for your custom filter!

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