ROAD AND WORKSHOP by HANDYMAN
Page 48
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Water in Rear Axles
WITH our modern trunk roads and Y, new by-passes it is hardly to be expected that any real depth of flood water will collect, even at the height of a storm. Only, in the worst instances momentary brake fade might be noticed. Off the beaten track, however, it is possible to meet with some depth of water, and after any prolonged immersion steps should be taken to ensure that vehicle lubrication is not affected.
To return to the trunk roads, things are not always what they seem, and at the higher speeds now attainable water can be directed or driven into vulnerable points. For instance, a side or forward positioned rear-axle breather can be in direct line with a stream of water flung rearwards from the front wheels of a tractive unit. At 30m.p.h. or so it may have little force, but at 50 m.p.h. it is another matter altogether, and water can then enter a breather more easily. Recent experience of this problem started with the complete failure of a differential unit, caused by washed out oil following a period of bad weather.
Water had entered the mushroom-type breather, sinking to the bottom of the differential casing, raising the level of the oil an forcing it out; the mechanism had then vibrated itself to destruction_ Tests with similar machines showed varying amounts of water below the oil, which was beginning to find its way past seals and showing at the brake back-plate drains, indicating too high a level. This caused the breather to be viewed with some concern and one remedy was to close down the forward-facing edge of the mushroom, or fit a small deflector in front.
A further modification was the simple one of removing the mushroom, and replacing this with the old pigtail breather of copper pipe. This proved quite satisfactory once the length of the pipe had been fixed at 2 in. above the casing.
If it is suspected that there is water in the casing, because of an increased oil level, it is a simple matter to check by easing the drain plug after the vehicle has had time to cool down. Without removing the plug altogether the water will drain off safely and separately from the oil; once oil begins to appear, the plug can again be locked up solid.