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CLASS B-MISCELLANEOUS SUPPLIES-Continued :
CLASS C—CHEMICALS, PAINTS, ETC.
Carbon tetrachloride, benzine, rust remover.
OVERHAULING THE GASOLINE ENGINE
Taking Down the Motor-Examination and Marking of Parts—Defects in
Cylinders-Carbon Deposits, their Cause and Prevention-Use of Carbon Scrapers—Denatured Alcohol-Burning Out Carbon with Oxygen-How Oxygen is Produced—Repairing Scored Cylinders—How to Repair Cracked Water Jacket-Inspecting Cylinder Packings-Valve Removal and Inspection-Reseating and Truing Valves—Valve Grinding Processes—Depreciation in Valve Operating System-Piston Troubles-Removing Piston Stuck in Combustion Chamber-Piston Ring Removal and Inspection-Fitting Piston Rings—How Wristpins are Held—Wristpin Wear-Inspection and Refitting of Engine Bearings-Adjusting Main Bearings—Crankpin Restoration-Scraping Brasses to Fit-Connecting Rod Bearings—Testing Bearing Parallelism-Ball Bearing Crankshafts—Camshafts and Timing Gears—Valve Timing MethodsSleeve Valve Motors–Eight-Cylinder V Motors—Precautions in Re. assembling Parts—Loose Flywheels—Two-Cycle Motors.
MANY car owners recognize the value of having the car overhauled before the inception of the active riding season when climatic conditions are not favorable to the continual operation of the car. In those portions of the country where cars may be kept in operation all the year round, a certain time each year should be set apart for giving the car a thorough looking over with a view of determining the points where depreciation exists, and the best methods of remedying the defective condition. The wise motorist realizes that this work of restoration is absolutely necessary. if continued satisfactory service is to be expected from the car. The motorist who shuns the expense of having the machine looked over and who operates it as long as the various parts function, is generally the one who is loudest in the condemnation of the automobile. In this chapter, the writer proposes to discuss the various steps incidental to overhauling gasoline engines of various types and in order to do this in a way that will be of value to the motorist or novice repairmen it is necessary to treat of the various parts in logical sequence. The suggestions given are all based on a practical experience with the repair of automobiles and nothing of doubtful value will be described.
Taking Down the Motor.-In order to look over the parts of an engine and to restore the worn or defective components it is necessary to take the engine entirely apart as it is only when the power plant is thoroughly dismantled that the parts can be inspected or measured to determine defects or wear. If one is not familiar with the engine to be inspected, even though the work is done by a repairman of experience, it will be found of value to take certain precautions when dismantling the engine in order to insure that all parts will be replaced in the same position they occupied before removal. There are a number of ways of identifying the parts, one of the simplest and surest being to mark them with steel numbers or letters or with a series of center punch marks in order to retain the proper relation when reassembling. This is of special importance in connection with dismantling multiple cylinder engines as it is vital that pistons, piston rings, connecting rods, valves, and other cylinder parts be always replaced in the same cylinder from which they were removed, because it is uncommon to find equal depreciation in all cylinders. Some repairmen use small shipping tags to identify the pieces. This can be criticized because the tags may become detached and lost and the identity of the piece mistaken. If the repairing is being done in a shop where other cars of the same make are being worked on, the repairman should be provided with a large chest fitted with a lock and key in which all of the smaller parts, such as rods, bolts and nuts, valves, gears, valve springs, camshafts, etc., may be stored to prevent the possibility of confusion with similar members of other
All parts should be thoroughly cleaned with gasoline or in the potash kettle as removed, and wiped clean and dry. This is necessary to show wear which will be evidenced by easily identified indications in cases where the machine has been used for a time, but in others, the deterioration can only be detected by delicate measuring instruments.
A typical four cylinder automobile motor is shown at Fig. 88, with all parts in place. In taking down a motor the smaller parts and fittings such as spark plugs, manifolds and wiring should be removed first. Then the more important members such as cylinders may be removed from the crankcase to give access to the interior
[+Valve Stem -Valve Tappet
Valve Guide 'Retaining Nut
and make possible the examination of the pistons, rings and connecting rods. After the cylinders are removed the next operation is to disconnect the connecting rods from the crankshaft and to remove them and the pistons attached as a unit. Then the crankcase is dismembered, in most cases by removing the bottom plate, thus exposing the main bearings and crankshaft. The first operation is the removal of the inlet and exhaust manifolds, next one uncouples the water piping from the radiator. There are various
methods of fastening manifolds on the cylinder casting, the most common being by retaining stirrups as shown in engine at Fig. 88, or by flanges and bolts as outlined in illustrations of engines at Fig. 89. As will be evident, where cylinders are of the T-head form with valves on opposite sides of the cylinder casting, the bolt and flange system is generally used. On L-head motors, where the valves are in the same extension of the cylinder casting, the bolt and stirrup retention method is generally followed. One may safely say that engines of low and moderate priced cars, being of the L-head form will have the manifold retained by stirrups and bolts, whereas the T-head power plant of the larger and higher priced cars will use the bolted manifold construction.
It is now common practice to cast all cylinders together, blocks of four being very common and blocks of six are not rare enough to cause comment. In some cases the manifolds are cored integral with the cylinder casting and it is merely necessary to remove a short pipe leading from the carburetor to one inlet opening and the exhaust pipe from the outlet opening common to all cylinders. In order to remove the carburetor it is necessary to shut off the gasoline supply at the tank and to remove the pipe coupling at the float chamber. It is also necessary to disconnect the throttle operating rod. After the cylinders are removed and before taking the crankcase apart it is well to remove the water pump, magneto, and mechanical oiler if that system of lubrication is used. The wiring on most engines of modern development is carried in conduits and usually releasing two or three minor fastenings will permit one to take off the plug wiring as a unit. The wire should be disconnected from both spark plugs and magneto distributor before its removal. The appearance of the engine shown at the bottom of Fig. 89, after the magneto ignition wiring, spark plugs and front of timing gear case are removed is shown at Fig. 91, A. The next operation in dismantling this engine is to take off the four nuts holding the induction manifold to the cylinder castings and when the manifold is removed the carburetor comes with it. The appearance of the engine after this has been done is shown at Fig. 91, B. The next parts to be taken off, the cylinder castings, are shown shaded in this view. The appearance of this engine after