545svk

Some questions around power steering fluid, if I may:
1) What is the total capacity of the system? For a 87 s4 Auto.
2) Is there a downside to using a fluid with a "build in" leak block?
3) Any big pitfalls to look out for when replacing the fluid?

I don't know when last mine was changed, and as it's a bit low I think new is better than top up.

Thanks in advance.

StratfordShark

Capacity 0.7L, so if you buy single 1L bottle you'll have plenty.

No idea about "leak block" but I don't like sound of it. Wouldn't want to risk gumming up pump, rack valves...

If you're changing fluid change reservoir. It's cheap and contains integral filter. If you're changing reservoir consider changing the supply and return lines (for latter you would have to cut off and replace just the short rubber section from crimped joint at fender to reservoir) if the lines are old. They get soft and greasy at reservoir nipples, where fluid will weep.

The fluid is messy and smelly! The most convenient place to drain is at the rack, by disconnecting lines here and letting them drain (move wheel with front wheels in air to get all old fluid out). Need new copper crush washers (2 per banjo bolt) when reinstalling lines.

When everything is reconnected fill reservoir. Have helper briefly run engine, then top up fluid that drains down to pump/lines. The level is checked with engine idling. Turning steering a few times lock to lock (don't push hard against stop) will bleed out any air.

Mrmerlin

What Stratford said!

Adk46

The thoroughness of a complete drain and refill is appealing, but since I don't have a lift I think I will do it "aquarium style". When you "change" the water of an aquarium, you drain only half the water and then refill. The fish prefer it this way. If you think of the fluid as having crap in it, doing this once gets rid of half of it. Doing halves at twice the frequency of full changes works out to be the same in terms of average crap level, and reduces maximum crap level. (The argument is similar for additive levels.) This ought to work with any car, not just sharks.

I've got a stainless steel baster to suck out the fluid, and I'll repeat it until I've consumed a bottle of fluid.

BRB-83-911SC

I believe the PS system uses ATF, not your typical PS fluid. Correct me if I'm wrong.

Mrmerlin

Use Dextron 4,5, or 6

GlenL

I don't think it does. It has the same maximum level of crap but a higher average level as the total crap never goes to zero. Instead of going from say, zero to half-crap it's going from a quarter crap to half crap. With a complete empty the average crappage is one quarter and with the double-time, half change the average crappage is three eighths.

StratfordShark

Curt I would love to have a lift, but I do all the work outlined using axle stands or ramps and just getting car up as high as safely possible. Taking the undertrays off is probably most tedious part of job!

I have also seen your 50%/twice as often suggested for coolant change when people have been shy of tackling block drains.

You would end up with Chinese soup after a few years of this routine...

Also you are not renewing reservoir filter, and when that is saturated who knows how much extra crap is being allowed through system and your valuable pump and rack?

ilikebig928butts

>>DO NOT<< put that self-plugging-leak-stop stuff into your shark's power steering fluid tank. Our cars use ATF.

mickster

I had a PS leak from the pump.

Had a rebuilt one in hand. Took apart the one in my car (thanks Pete aka El Greco). I cleaned all the gaskets (tried to find one that fit at Napa-should have bought the kit online). None of them looked bad or worn. Everything else was good on the pump. Put some instant gasket on the edges, bolted it up and never looked back. 1000+ miles later no leaks (knock wood) no issues and my reservoir looks like it's brand new inside. YMMV.

erioshi

My 928 also has Dextron ATF specified for use as the power steering fluid.

I changed mine out differently. My system smelled of conventional power steering fluid when I originally checked it before purchasing the car, and it also had the brownish color of power steering fluid mixed with ATF. I think it may have been a mix of ATF from the original owner and power steering fluid from the second. I also checked very carefully to make sure there were no signs of leaking or seepage from the steering rack.

To change and flush the fluid, I first drained the reservoir via the outlet hose on the bottom of the reservoir leading down to the PS pump. I placed a large funnel under the the reservoir and also emptied the pump hose. After that I re-connected the hose, refilled the reservoir again, started the car up, and worked the system. That was to try and get most of the old PS fluid out of the system.

After that step, I drained the reservoir again as above. To flush what was left, instead of opening the rack, I disconnected the reservoir inlet hose on the side of the reservoir, and routed that into an over-sized hose leading down to the drain pan. I then used a scrap bit of hose with a plug to block the reservoir inlet. I then refilled the reservoir again and had a friend start the car. They worked the steering wheel quickly back and forth a couple times while I emptied two more bottles of ATF through the system with the engine running and pumping out the fluid I was adding. After all of that I reconnected everything, and then refilled and bled the system. Now the fluid is nice and red, and there seems to be no hint of the power steering fluid that was previously mixed into the system.

The only reason I went to such great lengths with the process is that I had a prior experience with a car that an owner had used power steering fluid in when they should have used ATF. On that car I didn't catch problem early, and within a couple of months the car's steering rack was leaking out fluids almost as fast as I could add them. It was an expensive object lesson in what power steering fluid can do to seals and gaskets that are formulated for ATF.

All of this was done on with the car up on jack-stands and a typical oil drain pan on the floor.

Adk46

I just plotted it out, and you're both right - that I am wrong. I hate being wrong. And sorry to mislead anyone. At half intervals, the max eventually goes to the same level as the full drain routine, and the average is 75% of that level (versus 50% for the full drain routine).

However, it does work at one-third intervals (but someone should check my work). Of course, the filter needs to be changed at the regular intervals.

dr bob

^^^^ This method even for routine changes. Get a replacement reservoir (I should stock them with trans filters at this point...), a gallon of Dexron, and have a flush fest. Doing the system this way gives maximum opportunity to remove any wear particles in the system. Get those out regularly, and you dramatically reduce the chances of rack seal damage. The PS fluid and filter change recommendation is the sme as the auto trans fluid and filter interval. 25k recommendation from Porsche, half that in my garage. So for me it's every three years. Once I decie to get my tools read, it's little extra effort to do the PS at the same time as the transmission.

928Collector

for my 1991 928 GT, my owners manuals says replace power steering fluid with "ATF Dexron." But DEXRON is the trade name for a group of technical specifications of automatic transmission fluid (ATF) created by General Motors. For power steering fluid, it seems the 928s take a non synthetic power steering fluid. Anyone know what Power Steering Fluid 928s take? Ideally a 1991 928 GT? Can Dexron automatic transmission fluid, made by any manufacturer be used as power steering fluid?

The Forgotten On

They use Dexron ATF for the power steering. Just get a jug or Dex 3 or 4 and fill it. Should take under 2 qts or so, just get a gallon jug so you have it on hand anyway.

If you use power steering fluid in a 928, 944, 9 whatever of this era you will cause all the seals to fail really quick and leak fluid everywhere.