“ SUN ” SERVICE STATION

Sun (Auckland), Volume IV, Issue 953, 22 April 1930, Page 6

“ SUN ” SERVICE STATION

TELE ‘‘Motordora*’ section of The Sun Includes In Its service to readers a Queries and Anstrers 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 All communications must De accompanied by the Inquirer's name and address (not for publication), and sent to THE SUN “Service Station , MotordomTHE SUN, Auckland. Answers will appear weekly in this column.

“Brakes.”—l have an Austin Seven tourer, giving no trouble except an occasional jamming of the rear brakes. When the foot brake is even lightly pressed the shoes will suddenly grip tight with a severe grinding sound. This does not happen frequently, but it pulls the car up with a violent jerk. I have examined the brakes and all seem in order there. Have you any suggestion to offer as to the cause, and can you say if it is harming the car when it happens? I would like to know, too, if it is impossible to prevent the brakes screaming slightly when applied?

This trouble seems to be due entirely to the jamming of the brake springs. Are they in good order, free from bits of caked mud, and well oiled? The sudden stopping is not good for the car, although it will do not much more harm than straining the body bolts. Flaked graphite is the best thing for stopping screeching brakes.

L.P.VV. —I would be greatly obliged if you would advise me in the trouble of which I tell below: —My car, a Rugby, has done 8,000 miles. After registering 5,000 miles the car commenced to use an excessive amount of oil. At a garage I was advised to have the rings replaced. This I had done, oversized rings being used. No benefit resulted. I then took it to a recognised mechanic, who bored a number of holes in each piston. For a time it appeared to use less oil, but is now as bad as ever. He now advises having new pistons put in. Would a car with a mileage of only 8,000 miles need new pistons, or would the fact of having the rings replaced with oversize rings cause the trouble? Once when on a journey, when the car registered 2,000 miles, the oil pipe to the gauge broke, and the engine ran hot. Would this be likely to have caused excessive wear?

If the car ran ten miles or more after the oil line was broken it is probable that the cylinder walls are scored or worn. Bohnalite pistons fitted in a Rugby have clearances of only twothousandths and lack of oil is fatal. It is useless to fit new pistons. The cylinders must be rebored first, otherwise you cannot get a perfect fit and the oil consumption rapidly will be worse than ever. Have you examined the timing case bolts? The timing chain runs in oil fed to it at about 301 b pressure, and if any of the studs which secure the timing case to the block are loose, oil will escape in large quantities. Check this first.

M.A.C. —Being a constant reader of the valuable information given to motorists through the S.S.S." I would much appreciate some myself. My car, a Hodge, purchased new in December, 1926, mileage has developed trouble with the clutch. Facing downhill with engine idling it is impossible to engage any gear without clashing, this being necessary to stop gears revving. Facing uphill gears will cease revving some minutes after clutch is thrown out. but not immediately. At times with engine idling there is a decided dull knock about twice to each revolution. This will disappear when clutch is thrown in and out two or three times rapidly. With engine idling there is a rattling noise in the vicinity of the water pump. This disappears when the engine is revved up.

Dull thudding noise coming from the clutch is undoubtedly due to excessive wear or dragging of holes of clutch driving discs where they are located on clutch drive pegs, which are fitted to fly wheel. As the amount of wear in consideration of the mileage travelled appears abnormal, it occurs that this unusual wear has resulted from mal-alignment. which may have been caused by the rear engine support member coming in contact with a protruding road obstruction, such as a

boulder or perhaps a tree stump, which would sweep the cross-member in a rearward direction, and cause malalignment between engine and clutch This would also tend to make the clutch drag very badly, and there would be practically no clutch-plate separation during de-clutching. The correction of this trouble means the total dissembly of clutch unit and renewal of clutch driving discs, and possibly the clutch driving pegs, during which work the clutch thrust race calls for an inspection, also clutch spider and rear engine support member. As Dodge four-cylinder cars were delivered during the year 1926 with 12-volt or single electrical unit equipment, the appearance of foreign noise from about the water pump .of engine cannot be definitely traced without an inspection of the vehicle, either to timing gears or pump driving gear, If, however, the vehicle referred to is equipped with 12-volt starter generator, the cause of the noise will undoubtedly be definitely traced to timing wheels. The correction can be brought about by installation of new Textolite timing gear. We are inclined to think your vehicle is of the two-electrical unit type, and that the noise is due to some back-lash between the Textolite timing gear on cam shaft and pump driving gear, which can be corrected by regulation of shims or gasket between pump driving gear casing and crankshaft case proper. Some end play in pump driving shaft may also be detected, which can be eliminated by installation of a special type spring thrust washer. As both of these troubles call for the skill of mechanics, it is recommended that you take your car to the proper garage.