“SUN” SERVICE STATION

Sun (Auckland), Volume II, Issue 384, 19 June 1928, Page 6

“SUN” SERVICE STATION

FE “Motordom” section of The Sun will, in future, include in its service to readers a Queries and Answers Department, the object of which is to give accurate information regarding mechanical and touring subjects. Whatever the particular puzzle may be in either diagnosing irritating troubles, or motoring information of any kind, “Headlight” will endeavour to help, or refer the point to men who are recognised automobile experts in their respective lines. All communications must be accompanied by the inquirer’s name and address (not for publication), and sent to THE SUN “Service Station, Motordom,” THE SUN, Auckland. Answers will appear weekly in this column.

ENGINE STALLING O. J. (Belmore). —My car engine has developed a habit of stalling whenever 1 1 stop the car or am reversing or .coming slowly in and out of the Warage. It is hard to start, and 1 Frequently have to get out and flood Lie carburettor before it will tick over again. The obvious cause of the trouble would seem to be a bad adjustment of the slow-running jet. If the habit has developed recently, the jet may have been changed or altered, or possibly an adjustment set for warm weather is too weak for colder weather. If you cannot fix the trouble by changing the slow-running mixture, see if the petrol in the float chamber is as high as it should be. The float may be punctured, or the usual collar on the top of the needle which fixes the position of the float may have a broken arm or be stuck. This should be the seat of the trouble if the mixture is all right, and a careful observation will reveal its cause. AIRPLANE ENGINES Plane, Newmarket. —Can you give ime the following information:—(l) of airplane engines (air 'cooled) compared with motor-car engines (water cooled); (2) Grade of

lubricating' oil generally used in airplane engines; (3) Grade of petrol generally used in airplane engines; (4) Is second class petrol ever used? (1) Rather a complicated point. First, the actual heat in the combustion chamber is about equal. The temperature of an airplane engine, however, depends on whether the plane is moving. In flight the passage of wind cools an airplane engine of the fixed radial type which would overheat if remaining stationary. (The rotary type of airplane engine, of course, cools itself all the time.) (2) Good quality of any make, but usually oil with a percentage of castor oil in it. hence the use of “Castrol.” (3) Good quality of any make. (4) Never. RELATIVE EFFICIENCY Davidson (Ponsonby).—Which is the relative efficiency, horsepower for horsepower, of steam, motor and crude oil engines. The most efficient working engine is ! the internal-combustion, as developed for motor cars. If, however, you ! ‘mean utter dependability, steam comes i first easily. LEAKING WATER PUMP L.F.—Owing to a leak having de- ; veloped in the gland of the water pump of my car, the radiator loses a I

lot of water every day. I have tightened up the pump on its adjustment as far as it will go, but it still leaks. I -vgould like to know what else can be done to stop the leak. The trouble with the pump gland is that the packing has worn out. If you go on attempting to get the nut tighter, you will merely strip the thread and fall into some real expense for repairs. The remedy is simple. Unscrew the nut, and pick out the old packing with a penknife, then put in new packing. The packing is asbestos string Which has been dressed with graphite. A VARIETY OF QUESTIONS “Gasket” (Remuera).—The front wheels of a car are understood to ‘ lean outward” at the tops and to ‘‘toe in” in the front. Can you inform me the correct amount in each instance for a light car Bft 6in axle centres fitted with 30in x 3!in tyres? Also what amount of clearance in the mesh of crown wheel and pinion should there be to ensure quietest running and maximum life and efficiency. Thirdly, what is the cause of “shimmying” and how is it generally corrected ? (1) i-inch. (2) As tightly as is possible with smooth running. (3) Several possible reasons, but suggest rebushing of steering and all tie rods.