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Shadow
Hydraulics - Alan Dibley.
1971 Bentley T, 1982 R-R Silver Spirit (and a couple of Citroen CX
25GTis - the French Rolls Royce).
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I have just discovered your amazing series of useful info in Bill Coburn's TEE One Topics on this site. I refer to the section of T044b which deals with leaks from the levelling valve shafts. Can I add to the wisdom by pointing out that a significant reason for this leakage is a bad flexible pipe in the return line from valves to reservoir. These pipes close up inside after several years of use. The shaft seals in the levelling valves are in the return - low-pressure - side of the circuit and will not withstand high pressures. If the return line is blocked, when the system wants to dump oil the seals cannot withstand the many hundreds of PSI and vent to atmosphere. I found this after replacing the seals twice and then realising that there was nothing wrong with the valves and that the leakage only occured after two passengers got out of the rear seats. The flexible in question is the rearmost one on the left of the car - there is only one pipe shared between both valve returns. When I bought a replacement, and commented on the problem, the store man said that this is a common-ish occurence on many cars, not just posh ones. Pipes close up in similar ways in the high pressure side of brake systems but don't necessarily show the symptoms so clearly because a little oil at high pressure will always find a way through till it is totally blocked, then Aarrgghh!! The brakes fade because the pressure in the calipers is not released. |
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