Volkswagen carburetors are equipped with the very efficient oil bath type of air cleaner. In this type of cleaner, the incoming air is directed over the surface of the oil bath, causing a large portion of the dust contained to be retained in the oil bath.
Type 1 and 2 models have had numerous variations on the basic oil bath air cleaner. Most have some sort of an intake pipe or pipes, equipped with one or two warm air hoses. At low speeds, a weighted flap in the intake portion of the air cleaner is closed, causing pre-heated air from the cylinder head to enter the carburetor. At higher speeds, the flap is forced open by the force of the air, and pre-heated air is kept from entering. This arrangement makes it possible to have smoother idling and faster warm-up in extremely cold temperatures while at the same time allowing all of the needed air to enter the air cleaner at higher speeds. For summertime or higher-temperature operation, it is recommended that the flaps be held open by clipping their weight levers to the side of the intake pipe. In wintertime it is necessary that these flaps be allowed to rotate freely, because this helps to prevent the formation of carburetor icing.
On later models, the adjustable flap is replaced by a thermostatically controlled flap. On some units, the flap is regulated through a Bowden cable by a thermostatic unit mounted on the engine. On others, the thermostatic unit is located on the body of the air cleaner.
The oil bath air cleaner on type 3 models is similar to that of type 1 models, except for the presence of more extensive ductwork, needed because the same air cleaner serves both of the 32PDSIT carburetors of this engine. Also, the type 3 air cleaner is equipped with a second flap which allows air from the engine compartment to enter the air cleaner. Otherwise, air comes in from the slits on each side of the rear fender position. The fuel injected type 3 has a similar air cleaner.
REMOVAL & INSTALLATION
On type 1 and 2 models, the air cleaner is removed by taking the preheater pipe(s) from the intake tube of the air cleaner, disconnecting the thermostatic flap control wire, pulling the crankcase breather hose from the cleaner, and loosening the clamp screw that holds the cleaner onto the carburetor throat. After the air cleaner has been removed, the top part can be separated from the lower part by removing the clips that hold the halves together.
When the cleaner has been taken apart, the dirty oil should be poured out and the lower part cleaned. The upper part does not generally require cleaning. The bottom part of the air cleaner should then be filled to the mark with new engine oil of the same viscosity as that used in the engine. If there is no mark, refill with the quantity of oil specified in the Capacities and Pressures Chart.
Removal of the air cleaner in the type 3 dual carburetor engine is slightly more complex, but accomplished in much the same manner. The right-hand connecting rod must be removed from between the rotating lever and the carburetor, the cables removed from the automatic choke and electromagnetic pilot jet, the crankcase ventilation hose taken off the air cleaner, and the three wing nuts unscrewed. The center wing nut is removed before removing the air cleaner; those at each of the carburetors remain in place. After the center wing nut is removed, the air cleaner can be lifted from its position and the upper and lower parts separated.
When installing the air cleaner of the type 3 engine, care should be taken to see that the oil is up to the mark, that the rubber sealing ring on each carburetor is secure, that the water drain hole is free in the lower part of the air cleaner, and that the marks are lined up when the upper and lower halves are put back together. If the marks do not line up exactly, the intake pipe will point in the wrong direction and be either difficult or impossible to connect to the intake extension. When tightening the wing nuts of the air cleaner, it is very important that the outer wing nuts are tightened down first. There is an expansion-contraction joint between the left outer wing nut and the center wing nut which makes these not quite so critical. However, there is no such joint between the center and right-hand wing nuts. Subsequently, if the center nut is tightened first, then the right-hand nut, the result could be a slight movement on the part of the right-hand carburetor, thus causing an alteration in a very sensitive adjustment. Tighten down the center wing nut only after the two outer wing nuts have been fully tightened.Fuel Injected Engines
- Detach the crankcase and the auxiliary air regulator hoses.
- Loosen the hose clamps at either end of the air cleaner. Pull off the rubber hoses.
- Remove the wingnut and the air cleaner.
- Release the three clips. Remove the top section.
- Clean the filter assembly and refill it with SAE 30 oil to the red mark; SAE 10 may be used in arctic climates.
- Be sure that the red arrows on the top and bottom sections are aligned when reassembling.
- Reconnect the hoses, tighten the clamps and the wingnut.