ROAD AND WORKSHOP by HANDYMAN
Page 40
If you've noticed an error in this article please click here to report it so we can fix it.
Fuel Failure and Delay in Winter
IT is accepted that each winter will proI duce its usual crop of roadside fuel stoppages. Until these stoppages begin, it is rare to see any special precautions being taken. Yet quite a lot can be done to avoid stoppage and delay, particularly to those vehicles operating overnight.
To the driver who suffers the stoppage, there is little he can report, other than that the fuel has stopped flowing and his machine is at a standstill. In most instances he will inform you that the fuel has frozen. To the engineer there are two main causes of winter fuel stoppage, apart from complete failure of lift pump. air leak, or plain fuel shortage.
The first stoppage occurs when the air temperature through the vehicle is moving and reaches a degree of cold below that at which the fuel can flow. This means that the point set by the manufacturer at which his fuel will just flow has now been passed as the temperature dropped— and the fuel is at a standstill in the form of grease or jelly. The figure on the scale at which the fuel will again start to flow freely is termed the pour point. The fuel companies now set this point by the altered colour of the fuel at low temperature. rather than at jelly point. But what matters to the operator is that his vehicle can stop and be delayed.
Until recently this pour point varied between makes or brands: thus certain hauliers suffered heavily and Others escaped scot-free. At this time there is a fair understanding of the problem and with one or two precautions on the part of the operator, he can avoid the earlier stoppages, at least during daytime operation. However, on trunk routes, there are times between 3 and 5 a.m, when a vehicle moving at 30 or 40 m.p.h. in heavy frost can hit a new low on the temperature scale and fuel will stop flowing.
There are additives, of course, that will prevent this happenning—some safe. some unsafe. On long-distance night journeys they are not always available— in any case it is wise to discuss this approach with your fuel supplier before making a decision regarding additives, however well they may be advertised. It is far better to inspect your fleet in advance of winter conditions, and so clear them of any potential failure.
The second fuel line stoppage is. of course, water collected in the fuel tank and drawn into the pipelines. This stoppage is purely and simply ice. This will usually form in any loop or low point in the line, particularly so where the line, on leaving the tank, is looped under the chassis frame and back up inside the channel. Many vehicles operating today have this loop of pipeline almost at right angles to the approaching air—on a fast moving vehicle this section of line can be right in the path of really low temperatures.
Quite often, during repair or overhaul, pipes may be brought out in this fashion from the shelter of the chassis for some quite sensible reason, yet trouble is being invited, as the pipes are placed out in a position where snow or slush may gather
on certain vehicles. Pipelines start of quite well screened inside the chassis, only to loop out to join the filter or water trap, leaving a section fully exposed.
During a recent winter of frequent stoppages, two of the worst offenders were given special attention. All loops and exposed parts of the line were lagged with ordinary paintshop masking tape. which was then clear varnished. From then on these two machines cleared the winter trouble-free—whereas sister vehicles still suffered stoppage. The new synthetic tapes are well suited to this job.
To return to the frozen water problem. Whilst one can expect a certain amount from condensation, quite a lot of water finds a way in ,via the filler neck because of carelessness and lack of thought. For instance, a tank cap is missing for several days before being reported, its place being taken by three or four layers of rag or mutton cloth, often secured by an elastic band. Although it is wise to cover the aperture and allow air to pass in, water will also be invited by thc nature of the material used.
Another point noted was at a fuel island. Here, with gravity tanks, the hose hung downward all the way to the vehicle and it was found during heavy rain that water was trickling steadily into the tank as no anti-splash disc was fitted to the nozzle. Therefore, in heavy rain at uncovered pump sites, precautions must be taken to guard against this water risk.
Careless washing and hosing is another cause of water in the fuel, where the tank cap is not airtight. Here the wise mats will pop a plastic bag over the filler neck. Interest taken in the points described will go a long way towards giving trouble-free winter operation.