Black Power Steering Fluid

Submitted: Monday, May 29, 2006 at 06:24
ThreadID: 34357 Views:2453 Replies:7 FollowUps:4
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When I picked up the cruiser (and there is a story with that) I noticed that the PS fluid was as black as engine oil. I promptly bought a 5L container of ATF and flushed the system. The oil was fairly clean after doing this put within 100km was completely black again. Any ideas on whats causing this??

The level hasn't increased in the last 700km so I don't think its contamination from the engine. Still steers OK and doesn't make any noises.

Got me stuffed.
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Reply By: Member - John R (NSW) - Monday, May 29, 2006 at 07:07

Monday, May 29, 2006 at 07:07
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.
AnswerID: 175287

Reply By: dieselup - Monday, May 29, 2006 at 07:11

Monday, May 29, 2006 at 07:11
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
AnswerID: 175288

Reply By: Member - DOZER- Monday, May 29, 2006 at 07:32

Monday, May 29, 2006 at 07:32
You only drop half the oil in the system each time....i would leave it and do it again in 12 months....
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AnswerID: 175291

Reply By: traveller2 - Monday, May 29, 2006 at 08:09

Monday, May 29, 2006 at 08:09
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.
AnswerID: 175301

Reply By: Member - Hughesy (SA) - Monday, May 29, 2006 at 09:36

Monday, May 29, 2006 at 09:36
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.
AnswerID: 175311

Follow Up By: Sarg - Monday, May 29, 2006 at 22:00

Monday, May 29, 2006 at 22:00
Eng oil is being forced into the PS pump. The seal between the pump drive mount & eng is leaking.(Eng oil pressure being greater than whats in the PS pump body)
FollowupID: 431591

Follow Up By: Member - Hughesy (SA) - Tuesday, May 30, 2006 at 06:18

Tuesday, May 30, 2006 at 06:18
Thanks Sarg, I was hoping it wouldn't be that. Now I've seen resealing kits for the PS pump for under $50. Have you done one before and how hard is the job??
FollowupID: 431608

Reply By: Brid from Cost Effective Maintenance - Monday, May 29, 2006 at 11:04

Monday, May 29, 2006 at 11:04
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.

AnswerID: 175325

Follow Up By: Member - Hughesy (SA) - Monday, May 29, 2006 at 12:32

Monday, May 29, 2006 at 12:32
Thanks Brid. I originally just thought some clown had filled it with engine oil and a flush would fix but when it went jet black again in such a short time it had me wondering. Hope it is something like you suggest. Looks like I'll just have to let it develop and see what happens...
FollowupID: 431430

Reply By: burnsy - Monday, May 29, 2006 at 17:58

Monday, May 29, 2006 at 17:58
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.
AnswerID: 175438

Follow Up By: Member - Hughesy (SA) - Monday, May 29, 2006 at 20:06

Monday, May 29, 2006 at 20:06
Thanks Burnsy I'll check how hot it gets next time I go for a cruise.
FollowupID: 431536

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