This may help clear up some of the questions surrounding the QSM Air Cleaner and what options are available when ordering a new engine or for air filter replacement. These options ONLY APPLY to the SWAC (“dry” as I call them) versions of the QSM-11. The attached pictures (at the end of this article) show all the basics as to relative sizes, shapes and general construction.
The unit from Walker Engineering (Cummins factory option AC 2039 ) seems very high quality, and when examined carefully, shows it is a fabricated steel assembly made from multiple pieces of formed sheet metal, all very professionally tig welded together, is powder coated with a heavy black glossy finish, has some sound deadening material on the inside, uses a replaceable element of similar design to both K&N and S&B filters, and, I am sure, does a very good job in recreational low annual hour applications.. I do not believe the sound deadening part is replaceable and do not know how long its effectiveness would last. The Walker unit is high end as to price and runs about $600~$700-ish direct from Walker Engineering, or adds about $500 to the engine price (over the Racor unit) when bought from Cummins.
The other “factory” Cummins AC option for the QSM ( AC 2038, supplied from about 2001 thru current), is made by RACOR, and is described in the Cummins option database as a “low cost option”… The earlier designed units (Far right in the image below) had issues with the internal wire mesh rusting and being ingested by the turbo chargers. I believe that Cummins had addressed this issue years back. Not cheap for a throw-away, as the unit runs about $350, but works just fine, at least for a while or when new.. Probably a 2-3 year unit max, but I’d be checking it once a year or more (thorough inside inspection).
Before 2001, the QSM-11 came with a very heavy duty unit made by Racor which was on the bulky side, but never gave any issues and is still in use today with many of the early engines I sold and installed back then.
And lastly, we supply a unit (center picture) that can be mounted up, down, or sideways – has the 1.25” CCV fume connection fitting on the end, (a much better place, IMO, especially when the unit is mounted down-ish), has proven itself in many commercial high hour applications, is 100% trouble free, and is VERY economical by any comparison, although it may not be as pretty… Because our elbow is “soft”, it makes for a much nicer “squeeze by” in a tight engine room….Our replacement element is custom made by S&B Filters and has a flow rating applicable to 700-800 HP diesels in recreational use, is 100% cleanable, and will last for many years even in commercial service……… Air cleaner maintenance and a close “eye-ball” inspection should be done once per season, or more, regardless of what air cleaner option you choose………………