Black Power Steering Fluid

Black is usually from the blades in the pump wearing (if it's a vane type pump). From memory, the blades are made of some sort of composite impregnated with graphite.

Some discolouring is normal, but how much - haven't got a clue. You could try flushing it a couple of more times (if it's high km), but personally I wouldn't be too concerned. The only other thing I could think of is hose deterioration, but I think that would be extremely unlikely.

Hope you sort it out.

You'll probably have to flush it 3or 4 times because the complete system will need to be flushed .After the first flush it 'll still be mixing with any old oil in the system so keep changing it every week or so and it should clear up

You only drop half the oil in the system each time....i would leave it and do it again in 12 months....
Andrew

Might be worth getting it looked at as the power steering pump on the 1HZ is on the front of the crankcase and 'could' be contaminated by engine oil if something has gone wrong. I've worked on several 1hz's with mileage far higher and much older than yours which still had original clean fluid.
If the black is coming from within the power steering system it isn't good.
Draining and flushing does only change some of the fluid each time unless the engine is running and the return line is disconnected and run into a bucket and someone is pouring new fluid into the reservoir.

Yeah I flushed thru the full 5L of ATF by disconnecting the low pressure return line and stop starting the engine and collecting the dirty fluid in a little container and topping the reseviour up until it started coming out fairly clean (flattened the battery in the process).

I would have thought if one of the seals in the pump where it drives off the engine had failed then the power steering fluid would have been pumped into the engine not the other way around. But as I said the level hasn't changed so its got me buggered.

Might have to give Mr Toyota a ring and see if they can shed anymore light on the subject.

A possible explanation is that a previous owner may have added a Molybdenum dusulphide anti wear additive in the oil. This used to be a popular antiwear in the past, although not as much now. It is based on a black moly paste. I'd certainly investigate this aspect, prior to pulling things apart.

Regards
Brid

ATF used to have a additive like varnish in it & it will turn black when overheated.
Check to see how hot the oil resevior gets after a drive. 70degrees C is ok & a good rule of thumb is you can put your hand on it for about 2to 3 seconds.
If it is hotter than this I would look for a fault in the ps system.