How fuel filters impact engine health

Source: Fleet Equipment Magazine

Fuel is the lifeblood that runs through the heart of your tractor—the engine—sending power into the truck’s component circulatory system. The key to your equipment’s on-highway heart health lies in the engine getting plenty of exercise as it rolls towards its million-mile goal, and to make sure it’s fed the cleanest diesel fuel possible. The fuel filter plays an important role in ensuring that your engine keeps pumping efficiently. Like all components in today’s trucking environment, fuel filters have evolved to meet the growing needs of today’s hard-working engines.

“Fuel systems have changed and filters have evolved to protect critical components,” explained Donald Chilton, vice president of product management for WIX Filters, which offers more than 500 different fuel SKUs for heavy-duty trucks and equipment. “Cellulose is a filtration standard media and works very well for a lot of applications. As the protection need has increased, the medias have evolved as well. More advanced medias today are multi-layered composites offering efficient performance while stripping water out. Given the pressures at injectors today, water is just as damaging to an injector as actual dirt.”

Tougher emissions regulations have led to engines with high-pressure fuel systems, which require extremely clean diesel fuel and also increase demands on the engine components like fuel filters. Scott Grossbauer, Donaldson Co.’s director of clean fuel solutions, explained:

“The past EPA focus on emissions has driven design changes in engine injection systems that allow for very precise, metered injection of fuel. This gives original equipment manufacturers the opportunity to achieve a better balance of reduced emissions and increased fuel efficiency—translating into more miles per gallon. One of the ways injector manufacturers have helped achieve this balance is by increasing fuel injection pressures. To get the precision needed, fuel is being pressurized to 30,000 PSI and higher. Because of these higher injection pressures, the fuel itself has to be cleaner than ever before. Even the smallest particles, down to 1 to 3 microns, can do significant damage to injectors. As a result, the job of the filter becomes even more critical. It needs to provide the highest level of injector protection, while still reaching its expected service interval.”

Fuel cleanliness is extremely important to fuel injector performance and filtration manufacturers have risen to the occasion.

“In the last 20 years, single layer media applications have evolved from simple glass and cellulose construction to multiple layers of synthetic-polymer nano fibers that further improve field life and water removal efficiency in poor quality fuels,” explained Daniel Stibel, Racor’s fuel filtration product manager. “In the last 10 years, there has been a move to coalescer element designs that utilize four or more special layers to break water-fuel emulsions in biodoesel blends and poor quality fuels, which is normally difficult. In the last few years, Racor medias, for example, have been re-engineered to have low formaldehyde content while retaining all the life and performance features expected of the Aquabloc family of medias.”

Fully synthetic, multilayered media is a big step forward in terms of being able to remove the smallest particles of contamination with high efficiency, explained Cindy Hawkins, global product manager for fuel at Cummins Filtration.

“Efficiency is important to understand,” Hawkins began. “For example, let’s target 4-micron particles. If 100,000 particles enter the filter and 1,333 make it through, then the filter’s efficiency is 98.7%—it removes 4-micron-size particles 98.7% of the time. This type of performance is quite good and typical of our previous-generation media.”

Hawkins noted that today’s fuel filter media take filtration efficiency to another level. The NanoNet technology offered by Cummins Filtration, for example, can remove the same 4-micron particles 99.9% of the time. That 1.2% improvement might seem minor, but in reality, it means that of the same 100,000 particles flowing into the filter, only 100 particles make it through the media. A 1.2% improvement in efficiency is actually a 13-times improvement over traditional filtration.

All fuel filter media improvements seek to increase efficiency in removing particulate from fuel, and many filtration manufacturers are looking to performance above and beyond today’s standards.

“New tests show the performance of filters in dynamic conditions that may include vibration, pulsation and flow variation,” said Veli Kalayci, director of engine liquid products for Donaldson Co., which offers its Donaldson Blue filters featuring Synteq XP media to remove four times more contaminant from fuel. “This testing is becoming an important tool to differentiate filter technology and allows customers to make informed decisions on how to protect fuel injection systems. While protection is a key consideration, fuel efficiency is also affected by the condition of injectors, which makes high-quality fuel filtration even more important from an overall cost of ownership standpoint.

Fuel for thought

The fuel coursing through the truck’s network of hosed veins has evolved as much as the equipment itself. The introduction and growing acceptance of biodiesel and ultra-low sulfur diesel (ULSD) have made it more difficult for fuel filters to remove water from the fuel.

“The presence of water in biodiesel can also lead to microbial growth, which can result in reduced filter life,” said Layne Gobrogge, Luber-finer’s director of heavy-duty marketing and product development. “Water itself is damaging to the injectors and other fuel system components, and negatively affects heavy-duty engine efficiency and performance, with low power output and engine shutdown being common occurrences.”

In order to combat this problem, Gobrogge explained that Luber-finer has developed its new MP995 Fuel Filter for use on trucks that are powered by ultra-low-sulfur/biodiesel blends. The MP995 protects the latest common rail high-pressure fuel injection systems by being 99.5% efficient at removing particulates and 95% efficient at removing emulsified water from biodiesel.

Luckily, biodiesel blends are becoming more standard, according to WIX’s Chilton. “In the past, an out of spec blend could cause big trouble with the entire fuel system,” he related. “The BQ-9000 quality system the bio community is using helps blenders keep higher standards and keeps fuel quality high at the pump.”

The move to ULSD, on the other hand, required the addition of fuel additives to help with lubrication of the fuel system components, which was previously provided by the higher sulfur content in the fuel.

“These additives have made it more difficult to remove water from the fuel, which can cause injector damage,” Gobrogge said. “This puts the onus on fuel-filter manufacturers to develop products that can adequately and reliably remove any impurities from the fuel before it is burned, while being compatible with today’s engine designs.”

Heavy-duty heart health

Clogged filters can cause reduced fuel flowing to your truck’s combustion heart, causing it to seize and, eventually, fail. If your fuel filters are failing before their routinely scheduled preventative maintenance check ups, you need to dig into the symptoms of the diesel disease. First, to verify that the filter being used is of the correct micron rating for the application and also analyze any “plugged” filters to determine the type of contaminant such as microbial growth or particulate such as rust, scale, etc.

“This determination on the source of problem is critical to ensure he is using correct filtration product. The worst thing the fleet manager can do is outfit rolling stock with substandard fuel filters,” Luber-finer’s Gobrogge said. “To ensure that the fleet stays on the road, the fuel filters used should feature all-metal housings, possess high levels of pulse fatigue and burst strength, have easy-turn and low-torque valves, and a high-performance filtering media.”

“Filter manufacturers design fuel filters to provide the level of filtration protection specified or required by the OEM. Substitution of a less efficient filter may prolong a filter’s life before plugging occurs,” Cummins Filtration’s Hawkins echoed, “but it will also allow contaminants to pass downstream which will eventually impact the life of the other, more expensive fuel system components.”
Heating diesel fuel above the cloud point is the simplest and most reliable way to avoid plugged fuel filters. It is desirable to heat the diesel fuel as close to the filter element as possible, to re-liquefy wax and ice crystals.

“Now more than ever, fuel conditioning with heat is helpful for biodiesel to improve flow through filtration media,” said Robin MacDonald, sales manager for FTG Inc. “Larger filter assemblies with more media surface area can also reduce fuel system restriction.”

MacDonald went on to suggest regular draining of primary separation chambers in filter assemblies to remove accumulated water and contaminants, and double-checking that the element micron rating meets the engine manufacturer’s specifications. “In many cases a 30 micron or larger primary pre-filter/element can meet fleet PM intervals and offer reduced down-time due to premature secondary filter/element clogging,” he said.

Keep in mind that, though it may seem counterintuitive, a filter that plugs is actually doing its job by protecting a fuel system from contamination.

“A premature filter plugging event observed by the end-user is often a symptom of a problem with fuel quality rather than a problem with the filter itself,” Donaldson’s Grossbauer explained. “As for best practices with fuel, it’s always good to know where you fuel is coming from and what additives are being used. Over utilizing additives can cause filters to plug or, if the temperature drops and the fuel blend isn’t correct, it can also cause filter plugging issues.”

It’s important to remember to follow your manufacturer’s maintenance guidelines to ensure proper fuel filter utilization. Don’t forget that your fuel filtration supplier can also help with any issues, and it’s a good idea to ask them what steps they take to reduce condensation and other contaminants during transport and deliver, and what you can do at your fuel islands and storage tanks.

“In no case should a less efficient filter be substituted to fix a perceived problem with premature plugging,” Hawkins concluded. “Short filter life is usually a symptom. The best way to improve it is not to invite contamination in the first place.”