The AirSep is really just a glorified air filter. The filter element can be cleaned instead of just replaced. The reason I chose the AirSep over an ordinary paper filter is because of the claim that it reduces oil consumption and leaks. The system is also supposed to quiet the engine by a few decibels (we'''ll see about that).
As designed, the Perkins 4.108 sends blow-by from the valve cover directly back to the combustion chamber (via the flame arrester/air intake) and burned. Any oil mist is essentially burned away, or it plugs up the ridiculous little air filtration holes in the flame arrester. Once those holes get plugged, you'''re starving the engine of air. Now you'''re wasting both fuel and oil.
The AirSep replaces the flame arrester with a traditional air filter. It also routes the valve cover blow-by back to the oil pan, i.e. recycles the oil rather than burning it. It'''s a closed system and the manufacturer claims that it creates a negative crankcase pressure which reduces oil seal leaks. While I'''m hopeful that this claim is true, I maintain a healthy amount of skepticism ''' keeps disappointment in check.
The installation wasn'''t too difficult. But, as I mentioned, Foley'''s claims that the unit is designed for the Perkins, and it'''s not. You'''ll need to fabricate a mounting bracket for the air filter, but the kit comes supplied with a piece of aluminum stock for that purpose. You also have to find a way to get the blow-by back into the oil pan. The blow-by line has a check valve that can be routed to the dipstick hole or an accessory port. I chose to route mine to the accessory oil-extractor port on the starboard side of the engine. I don'''t have the oil-extractor installed and don'''t plan to add it. The unused port is covered with a plate about 3/16''' thick. I drilled and tapped the plate to accept the check valve.
The only other issue is that the various hoses supplied with the kit are the wrong size for the air intake and blow-by nipple. However, they aren'''t so far off that you cannot make them work.
Foley's had the AirSep on sale over the winter for $450, I believe - a savings of $50. My kit was missing a few pieces, but Foley'''s mailed them to me. This is the universal kit, so you might find it cheaper elsewhere if you shop with that knowledge. I bought from Foley's because they said it was specifically for this engine.
The manufacturer claims that every major diesel manufacturer are including the AirSep as standard equipment these days. You can check them out at
http://www.walkerairsep.com.
My boat is still on the hard for a few more weeks, so I haven't run the engine yet to test it. Here are some photos of the installation. The hockey puck looking cannister is a vacuum regulator. The brass fitting in the bottom photograph is the check valve.