Is there a recommended interval for renewing the power steering fluid ?

I also have a question about the power steering fluid reservoir. does it have a built in filter ?

How is this cleaned, ultrasonic bath ?

Some years ago I had another make of car that had an identical looking reservoir (plastic type), which I tried to flush out with solvent. No matter how many times I flushed it, fine crud (like that caught by a filter) kept coming out, I eventually gave up & reinstalled it.

This worried me, because the crud has now been loosened & may damage the system.

Is a new reservoir the only answer ?

Thanks for any comments.

 

I'm not sure that there's a Porsche recommendation on change intervals, but there are some independent opinions that say that it should be changed at the same time you do an ATF swap. That means 25-30K on the 928 I figure.

The reservoir is the filter, so you swap the whole thing. No good way to clean the filter short of replacement. Fortunately, ATE uses the same reservoir/filter assembly on lots of cars so they aren't as rare/expensive as they might be otherwise. I don't remember the cost of the part from 928 Int'l but it wasn't high at all.

The hose from the reservoir to the pump is a favorite spot for leaks. None of the PS hoses are cheap, but this is the lowest cost of all of them. Consider replacing yours if the old one is hard/cracked/ugly. Saves a lot of mess from later leaks.

Rememeber also that the PS uses Dexron ATF, the same stuff that the auto transmissions use. Don't buy 'power steering fluid' for your 928.

HTH!

 

Thanks Bob, pretty much as I thought.

 

Hmmm...another overlooked maintenance item. Mine's unchanged after 155K miles. Original rack, original reservior, original fluid. Still looks cheery red.

 

If I remember correctly the reservoir and hose cost about $50. I've had the new ones sitting in the garage for months and plan to finally install them this weekend, along with most of the other parts that are in the same box.

 

I can see it now... Cruising comfortably across the Nevada desert at 170, barely into the boost. Starts with a tiny little pinhole leak, sprayong on the exhaust header. A little smoke at first, but the airflow keeps the flames tiny. Leak gets bigger, flames a little bigger. Soon there's no fluid left in the reservoir so the fire goes out before it eats much, but now the wheel is a bit stiffer on the high-speed bends. Bill switches off the AC to see if that smoke smell goes away, and the Montovani gets muted to see if there's a noise from the cavitating pump. Slow down then pull off the road to find no PS fluid left, just a dribble and a few wisps of smoke.

So, does Bill get back up to speed and a little more to make up for the minute lost at the side of the road, or does he get far enough off the highway there to let the other cars go by safely? Or does he change the hose and fluid this weekend? Inquiring minds want to know!

 

Power Steering Reservoir, '77-'95, P/N 928.347.015.05, $28.43

Power Steering HOSE - Pump to Res. '85-'95 P/N 928.347.445.05 $12.76

 

Remembering Bob's post stranded on the side of a highway: Priceless

 

Somewhere here I read a great tip:

Get a "turkey baster" $5 at market (long plastic tube with a squeeze ball on end)

Use baster to draw out as much of the fluid as possible, have a pan ready to catch and empty baster.

Refill with fresh fluid.

Drive car.

Repeat process 2 or three times and you have "flushed the system."

 

OK, dr bob, you got my attention. I have a number of neglected items to change this weekend. And Ross, you're pretty funny.

 

tlee,

That would be Porsche special tool # 9207, which comes with the blinker fluid flush kit:

 

The filter assy on Dave's car is different from the integral plastic housing/filter used on my S4. As Tlee points out, you can swap/dilute the fluid by just taking some of the old stuff out and replacing it with new a few times. Better might be to disconnect the hoses to the reservoir and let the PS pump push a bottle of ATF or two through the system and into the waste oil bucket, while cycling the steering rack from lock to lock.

My long-gone Saab Turbo had a steering rack made by GM Saginaw. The cars had a real weak spot there. My wisdom on the rack failures was that a somewhat regular flush as described above would help clear debris from the rack bushings and seals before it did a lot of damage. So part of the annual gearbox/diff/wheel bearings/CV/etc service routine included the in-service flush procedure I described above. In that case, the return line was removed and routed to the bucket, and a cap was placed over the return port in the reservoir. Start the car, keep the reservoir full, assistance turns the wheel side to side a few times. Pour a couple quarts through and you are ready to reconnect and fill. This had the added benefit of geting all the air out of the system, which firmed up the steering and quiteed the pump a bit. The regular maintenance allowed the car to reach ~300k miles with no rack problems while I owned it.

 

Wally,

Unfortunately it's this one that failed me consistently
Power Steering HOSE - Rack to Pump 85-90 928.347.447.05 Price: $185.36

 

A local hydraulics company should be able to rebuild the line for about $35. Be certain that they clock the ends correctly, and put the restrictor in the proper place...

 

Thanks Wally. That's what I ended up doing on two occasions for power steering, and several other occasions for A/C and AT lines