BOATKEEPER

Crankcase Ventilation Filters From Pacific Fishing, February 2003 By Terry Johnson, University of Alaska Sea Grant, Marine Advisory Program 4014 Lake Street, Suite 201B, Homer, AK 99603, (907) 235-5643, email: [email protected]

If you have a late-model, major-brand, ma- mon, however, to see a hose running straight Crankcase Vacuum Stops “Oil Slobber” rine , chances are that it came from the crankcase vent to the engine air A well-engineered crankcase vent filter sys- equipped with a crankcase ventilation filter . On older, naturally aspirated engines tem can do more than just clear the air. system. Caterpillar, Cummins, Detroit, John the result is minor, possibly slightly dirtier Plumbed to the blower, turbo, or intake Deere, and some other makers install vent combustion and earlier fouling of injectors. manifold, a closed vent filter system cre- filters as standard equipment on some or all On turbocharged engines the dirty, oily mist ates a slight vacuum or negative pressure of their marine engine models. Other manu- can coat impeller blades, foul aftercoolers, in the crankcase. The happy result is that facturers offer them as a factory or dealer and significantly shorten engine life. A less engine oil is forced past the rings into option, and there are good reasons for tak- source in the industry says that single- the combustion chambers, and crankcase ing that option if offered, or for retrofitting weight oils tend to pass directly into the don’t leak when the engine is run- your current engine if it isn’t so equipped. , whereas multi-grade ning, which eliminates a source of oil in All engines leak some combus- oils, which are specified for some modern the bilge. A pressure regulator ensures that tion gases past piston rings. These gases turbocharged engines, contain a butyl vis- fluctuating vacuum from the turbo doesn’t pressurize the crankcase and pick up en- cosity enhancer, which is more likely to impose excessive vacuum on the crankcase. gine oil mist as they leave via the - stick to turbo components. Detroit Diesel two-cycle engines (53, case vent. The volume of this “blow-by” Thus, it is important that blow-by be fil- 71, and 92 series) have air box drains (af- increases as the piston rings and tered to remove oil and soot before releas- fectionately known as “slobber tubes”) that liners wear, and at typical overhaul inter- ing it into the atmosphere or the air leak oil when the engine is idling. Attach- vals blow-by is double that of a new en- induction system of the engine. The element ments can be added to crankcase vent filter gine. In trucks these gases could escape into in a crankcase vent filter coalesces the hot systems that collect oil from the air box the environment, where they would contrib- oil mist into liquid and traps it in a . drains, eliminating another source of oil ute to air pollution but have little effect on Most units are designed so that the trapped headed for the bilge. the vehicle itself. In a boat’s engine room oil is returned directly to the crankcase. Several companies make crankcase vent or compartment vented crankcase gases Some hold the oil, to be drained and either filters but two dominate the marine market. would quickly coat all engine room surfaces discarded or poured back into the engine. Airsep, manufactured by Walker Engineer- with an oily film, making for a dirty work- Some vent filters are plumbed as “open ing, has long been regarded as the standard place, collecting dust and grit, and poten- systems” whereby the filtered gases are re- of the industry. Airseps have been factory- tially damaging any genset or other leased into the atmosphere. More common installed on marine engines built by Detroit electrical components in the engine room. now is the “closed system” design that re- Diesel since 1989, Caterpillar since 1992, Few engines are made any more that introduces the gases into the induction sys- and Cummins and Deutz since 1994, and vent into the engine room. It is still com- tem after crankcase vapor filtration. have been factory options on Luggers since the early 1990s. Walker makes literally doz-

FILTERED BLOW-BY GAS RETURNS TO ens of Airsep models for different applica- THE ENGINE AIR INTAKE tions, and a potential purchaser is advised

AIR INTAKE ENGINE CRANKCASE to study carefully the options before mak- FILTER BREATHER ing a choice. Their newly released CCE (closed crankcase evacuation) System is an improved version of the venerable Airsep. Most Airseps bolt directly to the engine

CRANKCASE air intake, and in addition to the connect- PRESSURE ing hoses and coalescing unit, also include REGULATOR a separate vacuum regulator, , and turbo silencer. A separate air box drain kit is available for two- diesels. Some COLLECTED OIL Airseps are designed for remote mount. RETURNED TO OIL CRANKVENT CRANKCASE PUMP (OPTIONAL) EMISSION CONTROL ASSEMBLY Airsep offers a “plenum” or mounting bracket to attach their unit directly to the A crankcase ventilation filter should be made below the valve airbox of the 6-71 and similar engines. The cover but above the oil pan. direct mount makes a neat installation where space allows, but where space is lim- is available from Racor. The engineered- ited, especially on some in-line engines with fiber coalescer filters cost about $20 and the air intake on the side of the block, a can be changed in a few minutes. The older filter unit mounted directly to it may ob- Racors use a foam rubber filter that can struct access to that side, so a remotely actually be wrung out as long as care is used mounted unit is the logical choice. not to tear it. Recommended replacement Racor, a division of Parker Hannifin interval for the foam filter is 500 hours. Corp., produces a wide range of filtration products and offers its own line of crank- Air Filters and Intake Silencers case vent filter units. Racor crankcase vent Some engine makers assume that marine filters and air filter/silencers are also stan- engines operate in a dirt- and dust-free en- dard or optional equipment on some Cat, vironment, so they don’t supply air filters. Cummins, and John Deere marine engines. Detroit, for example, didn’t put air filters Their earlier models, the CV820 and on most of its blower-equipped two-cycles. CV1000, were designed primarily for open are susceptible to damage systems on non-turbocharged engines, al- from dirt so most engines equipped with though with supplemental hoses and fittings them also have some kind of air filter. At they can be installed as closed systems on the same time, air intake and blower noise Racor's CCV line is a remotely mounted closed the naturally aspirated (blower) two-stroke or turbo whine is a major component of die- Detroits by returning the filtered vapor to system incorporating a drain cock for coalesced oil. Photo courtesy Racor. sel engine noise. the low-pressure intake side of the air fil- It’s possible to buy after-market air fil- ter. The newer line, called CCV, is strictly ters for makes or models that didn’t come a closed-system design. with them. A Parker subsidiary makes a All Racor units are designed for remote include some or all of the following: sev- “transitional inlet” (what Airsep calls a “ple- mounting. For CCV installation the hose eral feet of inlet hose, check valves, an air num”) which allows an air filter to be in- from the filter to the air intake is connected box drain collector, the coalescing filter stalled on in-line two-cycles, although it between the existing air filter (if there is unit, several feet of outlet hose, a vacuum increases the overall height of the engine. one) and the turbo by means of a “tap regulator (may be integral to the filter unit), Users say the filters do protect the engine sleeve” or a “through-hull” type of fitting. a tap sleeve or air filter connector, air filter from contaminants in the air, but don’t do a Both Racor and Airsep incorporate a unit, mounting brackets, and hose clamps. lot for overall sound reduction. drain cock and check valve that allow co- Both companies provide detailed installa- Both Racor and Airsep offer air filters alesced oil to return to the crankcase through tion instructions. and silencers compatible or integral with an auxiliary fitting in the . The first step is to select a location for their crankcase filtration units. The distinc- Engine output is the factor for determin- the filter unit if it is not going directly onto tive raspberry-colored cone associated with ing model selection, as they are sized by the turbo. It must be placed where not more Airsep is the air filter element, not the blow- blow-by volume in cubic feet per minute. than five feet of hose is required to connect by coalescing filter. Racor air filters are Take the engine’s rated horsepower and di- it to the air filter, and it should be somewhere housed in black fiberglass barrels with 4-, vide by 40 to get approximate blow-by between even with the valve cover to mid- 5-, or 6-inch outlets for attachment to popu- CFM. Actual blow-by volume of a new en- way down the engine block, but not lower lar size turbos. Air filters are sized by CFM gine is less but the formula takes into ac- than the oil level in the oil pan if the plan is of maximum airflow; CFM = rated horse- count eventual ring and liner wear. to let it drain back into the crankcase. Al- power ¥ 2.0 (four stroke) or ¥ 2.5 (two The coalescing filter unit offered by each low four inches under it to remove the bot- stroke). company is relatively inexpensive, but with tom of the case to change the filter element. The units are claimed to reduce intake the addition of hoses, fittings, clamps, adapt- The filter cases must be firmly attached, and turbo noise by as much as 6-10 dBa. ers, and air filters, a complete kit for either and hoses secured so that they don’t vibrate brand will cost between $500 and $1,000 in loose, and kept away from hot spots like the smaller sizes (up to about 600 hp). Kits exhaust manifolds. Supplied hoses usually for larger horsepower engines are more, and have to be cut to proper length. If a each turbo requires its own unit. “through-hull” type of fitting is used to con- Both brands have good reputations for nect the outlet hose to the air filter housing reliability and effectiveness, and choice is or turbo inlet tube, the nut must be secured mostly a matter of personal preference. Study with a thread locking compound so that the the specs and installation instructions for fitting doesn’t work loose and get sucked both before making a decision. Engine room into the turbo. space allocation may determine the outcome. Maintenance is minimal. Most units made by both companies have pop-up in- Easy Installation, Low Maintenance dicators that show when the filter is becom- Fortunately installation is pretty straightfor- ing clogged, but under normal use 750 Airsep offers units that bolt directly to the ward and can usually be done by the owner- hours is about the usual replacement inter- engine air intake, filtering air, coalescing oil, operator. A complete installation kit will val. An optional electric remote indicator and reducing noise. Photo courtesy Racor. That’s minor compared to the 110-140 dBa that a running engine produces, but it could be a noticeable improvement in the living quarters after engine room insulation has lowered the ambient sound to 65-85 dBa. Clogged air filters often are implicated in poor engine performance. To avoid prob- lems associated with clogged air filters while minimizing element replacement costs, install a filter restriction monitor, which measures suction at the turbo or en- gine air intake after the air filter. Some models have a visual indicator on the air filter outlet. Others may have remote- or dash-mounted indicators that are either electric or pneumatic Air filter elements for both makes are replaceable, and can be washed—Racor in hot, soapy water; Airsep in a special clean- ing solution (never use fuels or solvents). Air filters should be cleaned annually, ev- ery 250 hours (Airsep), or when the optional filter restriction monitor indicates (Racor). Once cleaned, air filter elements should be air dried and re-oiled before being put back into service. Thanks to Rick Serna with Parker Hannifin, and Michael Delillo with Walker Engineering for help with this article. ✦