ROAD and WORKSHOP y o ;Land m an
Page 50
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Almost Hobson's Choice'
FREQUENTLY the transport engineer is faced with that repair situation which he has come to dislike most of all. This is the one where every reasonable and economical approach has been tried, but with little success—and he appears to be stuck with the large job he wished to avoid. The job in question is a fairly lengthy crack in the cylinder, block of a big diesel engine. At the time, this engine, in excellent trim after a recent full overhaul (with the exception of this crack of course), loses around a gallon of water in 13 miles. This is going to he the direct cause of a ruined engine if not rectified.
All the recommended " stoppers " have been tried, including materials that had dealt quite successfully with Many smaller fractures, with a singular lack of success. Up to this point, the vehicle had operated without much delay to traffic (other than the several "midnight oil efforts" to stem the leak) but now it appeared that the engine would have to come out for a
B24 replacement unit, or a five-day repair.
However, one fitter with steam experience and endless patience, begged for a chance to solve the problem. His request was granted more or less as a forlorn hope and this is how he very satisfactorily tackled the job, The crack covered 14 inches in all and with all obstructions removed he set to work as follows. Starting half an inch ahead of the crack, he drilled and tapped an 0-25-in. B.S.F. hole. Then he threaded the end of an 0'25-in, diameter brass welding rod and screwed the rod home solid, nicking it about 0-020 in. proud of the block and snapping it off.
Aiming straight up the crack, he drilled in the join between rod and block, and repeated the exercise, this overlapping action taking him along the crack 0-125 in. each time. He was not able to use the normal twist drill each time because of hard patches; on these occasions he cleared the trouble with a masonry drill.
In a working time of 11.75 hours, he
stitched the crack from end to end making around 120 separate tappings. Finally, he lightly peened the protruding stubs level. He had some assistance—preparing the engine, reassembling and so on— which took up a little over four hours. Bearing in mind the expense if the engine had had to come out, the time spent on the repair was an excellent investment. With 17,000 miles clear of leakage—a fair test period—there is now a good chance of the engine operating satisfactorily to retirement.