Cleaning the Air Cleaner


LabelNumerous people new to Jeeps have tried to clean their oil bath air cleaner and found that the central cannister can't be taken apart.

In response to one question on the CJ-3B Bulletin Board, Chuck quotes paragraph B-25 of the Service Manual (see illustration at right):

"To service the air cleaner, unscrew the eye bolt on the oil cup clamp and remove the oil cup. Scrape all dirt from inside the oil cup and clean the inside surface with cleaning solution. Refill with new heavy weight oil SAE 30 or SAE 40 to the oil level bead and install the cup securely to the cleaner body with the attaching clamp.

"Also, the cleaner body (less oil cup) should be removed from the vehicle and cleaned at weekly intervals or oftener. To do this, loosen hose clamp, and remove hose from the cleaner. Detach breather hose from the fitting on the cleaner. Remove the two wing screws and lift cleaner from vehicle. Agitate the cleaner body thoroughly in cleaning solution to clean the filtering element. Dry element with air hose but do not re-oil.

"Install the cleaner body in the vehicle with the two wing screws and attach hoses securely. Carefully check the hose clamps and fittings on the breather hoses at frequent intervals. Loose connections will affect proper operation of the crankcase ventilating system."

InstalledDerek: "Weekly servicing is probably overkill unless the Jeep is being used heavily in dusty conditions. The service manual does also say, 'When dirt is not noticeable in the air, service the air cleaner each 2000 miles.' I would have to admit it's probably been more than that since I cleaned mine (left)."

Jyotin: "Many shops have what is called a sonic cleaner. Without getting into the details it is a cleaner that vibrates the dirt out with heat and solvent. I am certain they would do it for a small fee. Or you could also use kerosene (carefully).

"Now, the following is my two cents' worth piece of advice since you asked -- do NOT use gasoline to clean it out. Life is too short and the flash point is too low to use gasoline as a solvent. The tiniest of sparks could cause a chain of events that is painful even to imagine."

Oil levelBart warns, "Whatever cleaner is used....kerosene, gasoline, parts cleaner, the mesh (and inside of the unit) cannot be left without oil covering it for more than a very short time. Even to leave it squeaky clean overnight can allow it to rust. Once it is clean flush it with kerosene as that will leave the important coat of oil on all interior surfaces. Then fill oil cup to mark."

Be careful with some of those parts cleaners. My dad used something called Quik oil remover once. He left the spray bottle on the fender, and the bit that leaked out took off four coats of paint."


Gavin Ferguson: "Here's a part number that may be of interest to folks that want to get rid of the oil bath style cleaner. This is for a K & N air filter, PN RU820. Unless the store has a huge in-stock inventory, it will most likely need to be ordered, but that isn't a problem.The filter connects to the horn (#1) where the flexible connector (#2) attaches." See Gavin's photo of the K & N filter installed (90K JPEG).

Carel writes from Spain: "I tried to get the K & N filter but was unable to order it. Still I wanted to do away with the bulky, inefficient and cumbersome to clean, oil-bath aircleaner, and after some shopping around ended up installing a paper air-filter meant to go in a Peugeot 106. It's a cylindrical filter with a closed top and a molded-on plastic mouth piece that fits exactly into the original flexi rubber hose, held in place by the original hose clamp.For the breather hose coming from the oil-filler neck one will have to install a small bulkhead fitting or some sort of tube on the original metal neck connecting the carb and the flexi hose. Suction via the air intake is needed to create some negative pressure (my theory).

"In the USA and Canada the Peugeot 106 is probably not on the market but Europeans can pick up a filter at any parts shop. I bought mine in an Eroski supermarket for 10 euros; an original Bosch filter no less! (Can't remember if it was for a diesel or gasoline engine.) I took the oil bath filter out, adjusted mixture on the carb and it runs great. Never before did I calculate the gas mileage (some things are better left unrevealed) but curiosity took over, and I get around 7 kilometers to the liter and getting to our house involves driving up a very steep mountain road for about 3 klicks, some stretches even in second gear. The rest of my driving is all city driving.

"I like to think that the large filter surface gives less restriction and therefore a better aspirated engine. The filter is so light that I didn't even bother to fabricate some sort of bracket to hold the thing up. In my book buying a 10 euro filter once or twice a year beats cleaning that wicked oil bath thingy hands down. Any improvement in gas mileage I'll consider a bonus."

Thanks to Tech Editor Andy Stock, and to Rus Curtis and Jim Allen for photos. -- Derek Redmond

See a good article on Willys Air Cleaners at The CJ-3A Information Page.

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Last updated 20 November 2008 by Derek Redmond redmond@cj3b.info
All content not credited and previously copyright, is copyright Derek Redmond