The interweb is an amazing thing. Once you know what your problem is, there’s bound to be something out there to help you solve it. It would be more useful if it told you all that stuff before the problem occurred, but somehow that never happens. Which brings me to the question of power steering pumps, about which I now know enough to bore you senseless.
Looking back, I find that we’d already replaced the p/s pump once, because it wasn’t giving pressure. We then replaced it just before the rally for the same reason, but the pulley then wasn’t tight on the shaft. (Pressing the pulley onto the shaft, and expecting it to stay there, is one of those really naff American engineering ideas.) Then we replaced the pump again before day 2 and the pulley was welded onto the shaft, and even that didn’t last. Are you beginning to see a pattern here?
The reason for these repeated failures is now pretty clear. The p/s pump had a remote reservoir, connected to the pump by a flexible hose. The pressure side of the pump goes to the steering box, the return from there comes back to the tank, from which the pump is sucking fluid. And it sucks big-time. According to my new friends at KRC, this pipe should be able to withstand a vacuum of 28” Hg., and if it’s not, it will collapse under the suction of the pump – especially if there’s a bend in the pipe, which there is. And when that happens, the pump will fail – either the seals will fail, or the pump will stall, in which case something else will give – like the non-existent bond between the shaft and the pulley, for example. Apparently this is the biggest cause of p/s pump failure, but you can eliminate this potential weak spot by using a bolt-on reservoir.
A new GM p/s pump is Dh 1700, without a pulley or a reservoir. An after-market KRC pump with bolt on reservoir and splined pulley is only slightly more. Yes, 17 splines give the pulley something to actually grip onto, and a nut tightened to 46 lb/ft to make sure it damn well stays there. I like the sound of that. So I’ve given the plastic another good spanking and ordered a shiny new pump with all the toys, and eagerly await its arrival. The only downside of this arrangement is that a bolt-on reservoir tends to make the fluid run hotter, but since I will use a slightly larger 6.5” pulley, the pump will run slower and hopefully that won’t be too much of an issue.
No-one has been much help on the ARB front diff problem. I have the part number of the flange which I need to replace, but even appealing direct to ARB hasn’t produced any response. So I guess I’ll run with the standard front diff.
Last weekend I was down in Liwa to run through this years Day 4 route (basically last year’s day 3) for Abu Dhabi Desert Challenge, to check that no-one has built any new roads, fences, camel farms or other obstacles in our path. Turns out the only major issue is at the start, where last year’s seldom-used gatch track is now a major construction highway, so they need to change that bit. The worst bit of the route – and of the rally – is the section from Ghayathi Rd back to the Crescent Rd, about 30km of unadulterated hell. Driving it with no vehicle tracks to follow othe took us nearly 2 hours, during which the car wasn’t horizontal for more than about 5 seconds. One bowl follows another, and it’s as a soft as a very soft thing. And in another month’s time it’ll be even worse, and as hot as hell. At 355km, Day 4 looks like being a long, long day, and I foresee many cars being time-barred at PC4. Let’s hope we’re not one of them!
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