Air in the hydraulic system - yikes!

[Henry A Harper III]

> Been trying to diagnose this problem on my '86 5Ks avant. The first
> symptom was fluid overflow from the reservoir which I thought would be
> the accumulator not holding its fluid charge. Tested that out and it is
> fine.
>
> It appears that air is getting mixed in somewhere in the system. The
> return flow from the steering rack is charged with air since it bubbles
> up in the reservoir and causes the fluid to foam and increase its
> volume. The only explanation I can come up with is a leak on the vacuum
> side of the system which is really only the one line from the reservoir
> to the pump. I have replaced that line with no change.
>
> Could the pump itself be the problem? Perhaps a crack on the vacuum side
> of it? I can't think of anything else since the rest of the system is
> always under pressure. There are no leaks of fluid anywhere else. Of
> course the steering rack exhibits some air lock symptoms now (hard to
> initiate turns). Anybody BTDT and have a solution?

Yes, it is the pump. Not sure of the exact internal cause (pressure relief
valve failure?) as it hasn't happened to me...yet.

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