A Book of Helpful Tips on Overhauling a Vintage Engine - Including Car, Motorbike and Lawn Mower Engines

By Anon

A perfect book for the keen amateur engineer interested in restoring an old engine that has been lying around. Many of the earliest books, particularly those dating back to the 1900s and before, are now extremely scarce and increasingly expensive. We are republishing these classic works in affordable, high quality, modern editions, using the original text and artwork.

• Language: English
• Publisher: Read Books Ltd.
• Release date: May 31, 2013
• ISBN: 9781473380608

Book preview

Bicycle

Overhauling a Motor car

THE instructions given in this chapter cover in detail the overhauling of any kind of petrol motor-car, and will be the more easily understood after careful study of Figs. 1 to 10, which illustrate the elements and mechanism of a four-cylinder light car of the De Dion type. The real art of overhauling mechanism lies as much in what is left undone as in what is done. This is particularly true of car overhauling, because the conditions of working on the road so frequently make it very difficult for even the most practised driver or mechanic to form definite and correct ideas of what is required.

But even if the amateur lack the experience of the accomplished tester, he can go a long way towards obviating unnecessary work by reducing the overhauling to a system which recognises the necessity for first knowing what has to be done before starting work. Overhauling, in its right sense, is not altogether a matter of taking the car to pieces; it is very largely a matter of inspection. A careful examination of the car to begin with will more than pay for the time involved. Great care, however, must be taken in first finding out what the trouble is, as incorrect diagnosis may lead to a vast amount of unprofitable labour.

Wherever parts are worn sufficiently to justify their renewal, it will be advisable to obtain the spares as far as possible from the makers, as they have facilities for producing them in quantity from the most suitable materials; cases in point are the details of steering joints and of spring shackles, which can, of course, be made by the amateur, if particularly desired, but they will have to be case-hardened, and finished off with emery afterwards. In the case of steering joint connections, however, the greatest care must be taken in the selection of the best possible steel, for life and limb depend on their work, and for this purpose, therefore, do not use any of the alloy steels, such as nickel, nickel-chrome, or vanadium steels, as these require special heat treatment, and without great experience in this matter the amateur is almost bound to go wrong. Indeed, the more one studies the subject the more one is driven to the conclusion that the overhauling of a car is a matter of inspecting and renewing, rather than actual bench work repairing.

Fig. 1.—Side View of Motor-car Chassis

Fig. 2.—View of Chassis from Above

Fig. 3.—Section Through Steering Pillar, etc.

Fig. 4.—Part Plan and Part Section of Gear Box, etc

Fig. 5.—Section Through Differential Gear

Fig. 6.—Section Through Carburettor

THE PRELIMINARY EXAMINATION, CHIEFLY BY SIGHT

Engine.—To begin with, make a careful examination by eye alone, beginning with the engine. First inspect the cylinders for any cracks, especially at the corners of the flanges by which the cylinders are bolted to the crank case. The water jackets, too, may be inspected for signs of water leaks. Cracked water jackets are more frequent than is generally supposed, because the expansion of the metal under heat often temporarily stops the leaks as the engine warms up to its work. Leakages on the inside of the jacket, of course, cannot be discovered at this stage.

The arms or brackets supporting the engine and gear box on the frame, also the bolts that hold them in position, should be carefully inspected, especially if a car has had much work on rough roads, or has been in a collision. If the reader is practised in telling by the sound whether metal is cracked or not, a few taps with a light hammer may prove instructive, but care should be exercised in this business, for be it remembered that the metal is only a casting, and, therefore, brittle under impact.

Bearings.—Throughout the mechanism of the car traces of escaping oil, or their absence, will generally give a very fair indication of the condition of the bearings, and in a preliminary survey the outside engine bearings may be taken as a guide to the condition of those inside, though, indeed, the latter will probably be in slightly better condition, owing to the favourable circumstances under which they work encased and in oil. Probably, the bearing at the flywheel will be most worn, as it has the heaviest work. If undue oil leakage shows at the bearings, the amount of play in the crank shaft can be discovered by engaging the starting handle, and holding it in position at its highest point, when a good pull upwards will often lift the front end of the shaft so that the amount of play in the front main bearing can be distinctly felt. Play at the flywheel end can be estimated by lifting the flywheel with a lever, but as it is a job possibly involving some risk of breakage, the end seldom justifies the action, for the condition of the front bearing should afford a reasonable index to the state of all. To detect end play, engage and disengage the clutch sharply, the thrust of which will move the shaft lengthways if there is any looseness in this respect. End play, however, is not so serious as radial wear on bearings.

It is just possible that bearings may be too tight, but, if serious overheating has occurred, the fact is evidenced by discoloration of the surrounding metal, while any oil in the neighbourhood will appear gummy and burnt.

Fig. 7.—Front End of Engine

Carburettor.—Sometimes a carburettor drips continuously. In a properly tuned carburettor, the height of the petrol in the float chamber should be exactly the same as, or the slightest bit lower than, the top of the jet, and continual leakage from the carburettor generally indicates that the point of the needle valve is worn, so that it does not cut off the flow of petrol until the level is above that of the jet.

Couplings, etc.—Examine the couplings of the magneto and pump shafts, and also the shafts themselves. Looseness of the ball races on the magneto can be discovered by shaking the end of the spindle up and down. Sometimes, as in the engine illustrated in this chapter, skew gear is used for driving either the magneto, pump, or camshaft. Move this laterally backwards and forwards to see if there is end play, which sometimes causes noises difficult to