Mike J

I have copies of the shop manuals for my 993, and there does not seem to be any mention of any maintenance of the Power Steering fluid..the car as 60K miles and I figure its best to change it? All they mention is checking the belts.

Also, there is a casual mention of the bleeding/flushing of the clutch slave circuit while bleeding the brakes...it seems to be in the same circuit?

Cheers

Anir

Mike,

I'm glad you've asked this question. I have not been able to find any guidelines on this either.

While my car was at the dealer recently to have the door check strap repaired, I requested that they "flush" or replace the Pentosin CHF-11 clutch fluid. They replied that there were no recommendations to do this, as far as they were aware, so it was not performed.

Seems strange that this fluid would not benefit from replacement, but then again, I don't know much about Pentosin.

Kevin

Your power steering system would benefit from getting a simple turkey baster, sucking it out and replacing the fluid. I also use this method on the from brake/clutch reservoir between a full brake bleed, which is nice on the C4S.

Timothy Stewart

Bleeding of the clutch slave cylinder
is mentioned in the manuals - p 47-9.

I performed the turkey baster routine
on my power steering and replaced the
fluid with Redline Synthetic. Noted
improvment.

tim

Mike J

Thanks! Will use the baster routine since it sounds the easiest (better than being under the car trying to bleed at the steering rack! ;-)

Sounds like the brake slave cylinder can be bled while bleeding the brakes....

Tim, what about your comment on "Noted improvement"? Was the steering easier, lighter or? What was it like before the fluid change?

I know they recommend "Pentosin CHF-11". Is the Redline stuff the same?

amfp

I also use the turkey baster for power steering. I use it three times - a couple of weeks apart when the fluid is hot. This seems to replace most of the dirty fluid quite well. As I recall the Pentosin CHF-11 is only used on turbo's or later model 993's. So on my 95, I use standard fluid recommended in the manual.

On my 944, I had what I thought a steering rack problem and a leak, but when replacing the power steering fluid both problems went away. So now "change" power steering fluid on all my cars every 20K. My change interval is a overkill, but to me is easy preventive maintenance.

In reading Kevin's response guess doing with brake fluid between changes can also have some value, but be careful of any drips as it will burn the paint.

Jascha-M

The bleeding/flushing of the clutch slave circuit can be done while bleeding (or separately) the brakes since both systems share the same reservoir. The reason the Dealer tend to abstain from doing this job is that it requires some dexterity (and effort).

The best approach is to use a pressure bleeder (with the p-car on a lift or raised on stands --be vrey careful!). You have to reach over the transmission and find the "nipple" on the slave cylinder using a 7mm (?) box-end wrench --the rest is patients..

Robin has a good description of this DIY as well http://p-car.com/diy/slave/

dwe8922

The service manual says that pentosin supercedes all previous power steering fluids. I found out that pentosin works much better with the rubber seals than the old p.s. fluid (ATF) did. I drained mine (old stuff) from the bottom hose, and it looked horrible. My steering became smoother after. PS rack failures are common, and I can't help but think that the fact the fluid rarely gets changed is one reason why.

Mike J

David,

Did you just "undo" the lower hose off the pump or rack and let the fluid drain out?

I need to check the manual to see if any special bleeding is needed for the power steering...I doubt it however. I don't have my car yet (next week its arriving), but the records indicate that the steering fluid has never been changed just like the factory recommends! Guess its to be added to the list of things to attend to as well as flushing out the clutch slave cylinder.

Mike

E. J. - 993 Alumni

My rack is leaking so bad that the fluid is filling up the tie rod boots.

I am probably going to replace it with a used one and use the new type of fluid. Could be a pain in the butt replacement - I wont know until I start in a few weeks.

Good advice on changing the fluid.

E. J.

dwe8922

Mike,
The easiest way I found to flush is to replace what's in the reservoir a couple times (driving it in between) to get most of the old fluid out, and then replace it yearly or so. I actually use a large medical syringe with tubing attached to it, and drew the fluid out. It works the same as a turkey baster, but no dripping. You can drain it from the bottom of the reservoir as well, but its tricky to get your container out from around the hoses w/o spilling. One can of pentosin should be more than plenty to do this.

David

Dick in TN

In the 993tt's there are two Pentosin reservoirs, one in front and the other in back. Presumeably they supply independent systems and aren't connected, with the rear reservoir supplying the clutch and the front the power steering. However the owners manual isn't definitive about this. Does anyone know if this is correct?

Edward

David,

Did you suck out the contents of the resevoir AND drain from the rack, itself?

Do you need to follow up at all by driving a while to cycle the fluid then drain/replace resevoir?

Finally, should I assume that (re: the Sevice Bulletin) Pentosin is compatible with whatever residual power steering fluid is left in the system.

Thanks!

Edward

dwe8922

Edward,
I've never drained it from the rack itself; that seems like a lot of work. Draining the res. will get more fluid out, but sucking it out is quicker. Mine had never been changed in 5 years, so I repeated the process of draining and filling several times to completely flush the system. After that thorough initial flush, I think draining and refilling once a year should be plenty. Yes, the car must be driven in between to allow the new fluid in the res. to cycle. Turning the wheel to its end point creates the most pressure, and therefore the most fluid cycling. The manual states that the fluids are compatible. All power steering fluids are basically ATF. Hope this helps.

David