In removing the valve cage the entire rocker assembly of all the valves must be lifted. When only the valve stem is removed, it is merely necessary to unbolt the upper part of the cage or housing which contains the spring. The valve stem will slip through the fingers of the rocker.
Fuel fuel line, as on all engines, fills with dirt and must be flushed with kerosene. There is no by-pass or relief valve on the fuel line. If the oil line becomes air-bound, the union at the valve cage must be unscrewed to allow the fuel line to 'clear. To avoid a messy appearance after a line has been emptied, a shallow pan can be constructed to receive the oil.
Starting starting purposes, it is customary for the manufacturer to furnish a two-compartment fuel tank, one compartment containing the fuel oil which, is used, while kerosene is placed in the other part. This kero sene is supplied to the engine in starting since it will ignite at a lower temperature.
McIntosh & Seymour Marine Diesel Fuel fuel valve of the McIntosh & Seymour Marine Engine, while using a Hesselman atomizer, has a cage and actuating rocker quite dif ferent from that described above. The cage rests in a bushed opening in the cylinder head. The rocker arrange ment is shown in Fig. 120. The rocker arm, at one end, is pinned to the vertical push-rod while the other end carries a hardened steel button in con tact with a dog which, in turn, raises the valve by its adjusting nut. The fuel cam, etc., have already been discussed in the preceding chapter.
The Snow Diesel Fuel Snow Diesel fuel valve is of the open type and is shown in Fig. 121. The valve is enclosed in a cast-iron cage which is held to the cylinder head by two studs. The cage extension carries the valve spring, which seats on a cast-iron bushing about the valve stem. This cage has a gasket at the cylinder head surface while a ground joint between the atomizer and head casting prevents water leakage into the cylinder. This arrangement provides an effective water-cooling of the valve cage without the necessity of a water cavity in the cage body.
The oil charge enters the valve cage at c, flowing along the check valve D, and comes to rest in the small cup or reservoir E.
The air from the compressor enters at 73 and fills the recess at A. At the proper time the needle valve II is opened; the air rushes out the valve opening, through the passage F and into the cylinder at I. In sweeping over the surface of the fuel charge at E, the oil is picked up and, as it is forced along through the atomizer disks C, is broken up.
Valve Stem.—The valve stem can be removed, without dis turbing the rocker arm, by unscrewing it from the spring bushing. In making adjustment for cam roller clearance, the stem is screwed in or out of this spring bushing as required. This allows a considerable shortening of the valve stem, from regrinding, before replacement is necessary. The lower part of the stem is grooved, and these grooves collect dirt and consequently should be cleaned occasionally.
Fuel Check cutting of the fuel valve seat due to dirty oil is avoided, the scoring is merely transferred to the check valve D. The oil is at all times in contact with this valve, and there is a strong tendency for the dirt to settle on the inner eiges of the seat. This will cause the valve to leak, although the scoring action is much less than with the closed nozzle since there is no high-velocity air stream present.
Atomizer atomizer ik provided with a series of fins about the peripheries of which are a number of notches, Fig. 122. These notches will fill with a tarry deposit when a heavy asphaltum base fuel is burned. The presence of these deposits is usually indicated by the engine requiring a high air injection pressure to maintain the correct speed. The atomizer disks should be cleaned at least once a month—more often if the oil is dirty. A spare set can be inserted and the old ones soaked in lye water.
Kiirting Diesel Fuel fuel valve along the same lines has been manufactured by the Korting Co. for some years. This valve, however, has no atomizer disks. The oil is swept into the cylinder by the passage of the air over the surface of the oil pool. This valve appears in Fig. 123.