ENGINE TROUBLES.
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Our Driver and Mechanic Readers Contribute a Few Useful Hints.
AS WE HAVE before remarked, in dealing, on this page, with drivers' contributions; engine troubles nowadays .arc few and far between. Not only is this true of modern engines, power units of new machines, but it applies with almost equal force to engines of old vehicles, thus rather going to confirm the opinion which we used so. insistently to utter in the old days that the frequent troubles of those times were more generally due to inefficient handling, the result of inexperience, than to inherent defects of design or construction. The four, letters with which we are concerned this week, although they do, as regards three of them at least, deal with engine troubles, are actually, in their nature, confirmatory of our view, -that difficulties wills the engine are now so infrequent as to be negligible_ One, from " M.M," of London, W., deals with a crack in a crankcase; such a crack as we never remember to have heard of before, either as to its locality or its nature. It is one which, we should say, -was due to a flaw in the casting. The letter is published, and the 15s. prize awarded to its writer, because of the effective, yet simple and skilful manner in which the defect was remedied,
This crack developed, he tells us, about 1 in. from the lower face of the top half of the engine case. It ran, as will be gathered by reference to the sketch, from the bored hole for a main bearing, for a distance of about 21 ins, along the web of the crankcase. Difficulty arose when tightening the bearing in place, owing to the fact, that one of the bearing studs crossed the crack, and, when the bearing cap was being tightened, the crack opened and prevented a proper grip being had of the bearing bush. A. special stud was, therefore, made with a collar or flange, as shown in the sketch. This, when screwed in place, had the effect of drawing the crack together and obviating the risk of it opening as the strain came upon it. How this comas about will be fairly obvious from the sketch. It is necessary to point out, however, that before this stud could be fitted as shown it was necessary to cut a recess in the casting to accommodate the collar. Moreover, this operation had to be performed without removing the crankcase from the frame. For this purpose a special tool, Which is also illustrated as one of the figures in the sketch, was made. An alternative and a much clumsier method of effecting this repair, involving the 'fitting of a plate to the cracked web of the crankcase, is indicated on the sketch—this, however, besides being open to the objection that there was a risk of it disturbing the alignment of the case, would have meant taking the engine right down, and would have involved the loss of the use of the vehicle possiblyfor two or three days, whereas the job as actually .executeci took only five hours. More unusual still in the way of engine trouble is the experience which occurred to " H.S.," of Camberwell, for who of our readers has heard of an inlet valve head breaking off, flipping across the cylinder in nice time to be able to get under the head of the exhaust valve, bending that, then falling on to the piston am'. smashing that! Yet, this actually occurred, as " H.S." tells us, in a lonely part of the country about midway' between two villages which werenine miles apart.
He came to the obvious conclusion thathis best course was to attempt to get home on three cylinders, but in making his preparation to do so, he unfortunately overlooked one equally obvious precaution' and thus prolonged _his troubles rather more than would otherwise, have been the case.
He took out the plug of this unfortunate cylinder, and in addition, to make assurance doubly sure, removed the magneto lead to that plug. He then tried to start his engine, and found that she would turn over a few times and then stop. A little of this, and it occurred to him to blank up the connection between the cylinder that was in trouble and the induction pipe, thus giving the other three cylinders a chance to draw explosive mixture from. the carburetter instead of fresh air via this cylinder.
He subsequently completed his journey, miming a distance of over 90 miles, on three cylinders. The third letter from " H.A.B.," of Rotherham, suggests a. refinement, and is not concerned with any actual trouble. He paints out that in his experience the majority of starting handles are not fitted with any device to prevent them from swinging, handle downwards, as the lorry travels. A good many drivers remedy this defect by means of string, with which they tie the handle up io the front duinbaron. He suggests the fitting of a balance weight, and ircludes with his letter a sketch which is repro duced herewith. It will be observed that thieweight is a half ring of metal supported on the spindle of the starting handle by a clip, and so located that when the handle is left to swing freely the balance weight brings it into the horizontal position with the handle well clear of the mud.
-The letter from " J.G.P.," of Wisbech, deals with a trouble that is more frequent, but it is not so much an engine trouble as accessory trouble, due mainly to the parsimonious policy of a good many manufacturers, when they are selecting such fittings as compression taps, to trouble with which this correspondent refers. These fittings, he says, are frequently to be seen shAdrn of their handles, not only being rendered thereby unsightly, but also difficult to use. They usually break off at the point marked " A " in the sketch. He points out that they can easily be repaired if a hole is drilled through the stem at this paint, into which a piece of brass rod may be fitted and soldered'.
It is a good plan, he says, before attempting to open tight compression taps, to give them a gentle tap at " B," thus easing the tapered barrel before excessive force is applied to the handle. [Will the writer of this letter forward his full name and address, which was omitted from his contribution!—ED.]