FORD VAN POINTERS.
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By R. T. Nicholson (Author of "The Book of the Ford ").
A CORRESPONDENT writes:— A CORRESPONDENT writes:—
"Could you please explain the reason of the following on a, Ford 1 Ton Lorry about 3 weeks old. Had been in use about 3 weeks.
427.—A Double-barrelled Poser.
(a) I would fill the Radiator with water and after travelling about 1i miles the water would be reduced by about 5 inches.
(b) Sometimes I would stop the Engine when I did not want to do and to restart it again needed a terrible swinging of the starting handle. Once I stopped it suddenly and the air hole at the bottom. of the Carburetter started to leak petrol. I plugged it and the car would only move on bottom speed and the mixture was very rich. After travelling about q miles thh _plug was taken out and the carburetter -was adjusted by means of the screw on the top and then the engine ran as ordinary.
(c) When I stopped at a road crossing I would get into bottom gear and then when I started to go again in top speed the car would scarcely move, and I would have to run into the side till the engine went cool.
(d) After travelling about I mile at night the exhaust pipe got red hot and I had to wait till it cooled down.
NB.—There was no water leakage and I always had the Ignition lever well advanced."
My Effort at Reply.
Now what would You say to that? At first thought, was inclined to suppose that trouble (a) was somen24
how connected with troubles (b), (c), (d). From description of trouble (a)., I was inclined to suppose that water might be leaking into the cylinders (either through a leaky cylinder-head gasket, or a flaw in the water-jacket), and so passing away in the exhaust as steam whenever the engine was running—also trickling into the inlet manifold. Any considerable leakage might account for the loss of 5 inches of water in 1i miles, and would certainly account for starting troubles' inasmuch as the water would (among otheamisdeeds) bridge the sparking-plug points. True, my correspondent assures me that there was no water leakage ; but in the circumstances described, he would not know of it if there was, inasmuch as the water would get away in the form of steam.
The first step I should take with a view to checking for water leakage into the cylinders, would lie to see if the level of the water in the radiator fell in course of a long rest. I should bring the lorry in nice and hot, and should then fill the radiator. After some hours, I should see if the radiator water-level had fallen. If it had, I should know that there was leakage somewhere. In the ordinary way, one would suspect that the leakage was at the hose connections, but I can hardly suppose that my correspondent would have overlooked that possibility. Wherever the leakage is it is pretty certainly not in plain sight. What makes me think that the leakage is through the combustion chamber is that the fall is somewhere about 5 inches—just about what it would be if there was such a leakage. There is another possibility—a cracked overflowpipe. (I have known of cases where the pipe got cracked.) In such a case, the water will gradually trickle out of the lower end of the pipe till its level is down to the bottom of the crack.
When trying to spot any kind of radiator leak, it must not be forgotten that some leaks only become noticeable when the engine is running at good speed, so as to cause plenty of vibration. Moreover, a radiator will sometimes leak when hot, and not when cold. The same remarks apply also to the water jacket.
The Probable Solution.
I rather think that my correspondent is "up against" two different troubles—that his water leakage has nothing to do with his difficulty in starting and in his bad firing. I should try to trace the troubles independently therefore—looking particularly at the overflow-pipe as the source of the water leakage.
Then I should "have a go at" the carburetter. I should suspect that it was choking the engine all the. time with petrol. That might happen from various causes, but most likely from one of two :—(1) The airthrottle at back of carburetter is stuck wholly or partly closed,"eo that there is no free way for air into the carburetter, as there should be ; or (2) the spray needle is screwed up far too high. A good many beginners get into trouble with the adjustment of the spray needle because it is (or should be) locked by the big nut surrounding it. When this nut is tight., it is usually impossible to turn the spray-needle down for more than a very little way. The consequence is that the beginner is apt to suppose that the -spray orifice is closed when it is not. The nut should be loosened, so that the spray needle can be turned right down. (It should be turned very gently down, or its point will be spoilt—and then good-bye to all decent carburation.) It should then be turned up for one turn, or a little more, when it will be " about right." (You can set it finely when you have the engine running, by
trying for the point at which you get the best running). Do not forget again to tighten up the lock nut. Going back to the other case—a stuck air-throttle valve. This sometimes does stick, generally owing
to its connections getting bent. See that there is clear way by the valve (which can be felt at the back of the carburetter), and that the valve stands " end on" so as not to obstruct the air flow. (Of course, this air-throttle.is generally closed for flooding the engine at starting, but should spring back directly the air-throttle pull-wire is released.)
Now a word as to trouble (d)—the red-hot exhaustpipe. It is by no means unusual for the top end of the exhaustepipe.to glow red-hot, especially after hard pinning. The fact that the redness is only seen at night is due to the darkness. The pipe is seen glow,ing between cracks in the footboards, and the driver is then apt to come to the conclusion that there is " something wrong." Still, it ought not to get redhot after a mile's run, unless the work is very heavy. In my correspondent's case, I am pretty sure that the excessive heat is due to use.of an over-rich mixture.
Trouble (b) is not uncommon, either. If the engine is suddenly stopped, there is nearly always a rush of over-rich mixture to the engine, and the engine will not then fire. The remedy is to screw the spray needle gently down, and then to turn the engine over lazily until it begins to fire again—when you rush to the spray needle, and turn it Slowly upwards4until you get perfect firing.
The question of what is a correct mixture for starting purposes is apt to be a bit of a puzzle. We are inclined to speak of a "rich starting mix ture " and to go on flooding and flooding, but, of course, this is all wrong. I will tell you a little story next week anent this. The Editor tells me I am at the end of my space for this week, which, in his case, is more than a plain hint.