[dlearl476]

So, I couldn't edit my other PS thread title, so I'm going to start a new one to post this info.


Like I mentioned in the other thread, I really didn't want to buy a new return line/cooler, so I did what I suggested. I dremeled off the crimped on hose fitting and replaced it with a hose and hose clamps. Two actually. Since the cooler pipe is 3/8" and the reservoir nipple is ~ 1/2", a got a foot of pretty blue Conti hydraulic hose from Eric's and a 90° 1/2"-3/8" elbow from Amazon. Replacing the supply line was pretty straight forward. I replaced all the worm drive hose clamps with SS solid Norma FI clamps. Various sizes to fit, 16, 18, and a 21mm for the big nipple on the supply side of the reservoir. Then I pulled off my PS pump belt tensioner and soaked it in DeepCreep. (The lock nuts were too tight to lossening them on the car)


Now here's the best part: I looked everywhere for good instructions about flushing the system. Unsatisfied with the results (the turkey baster method was the best I could find) so here's what I did. Hooked my supply line up, and plugged the return port on the reservoir. Hooked the return line to my Motive suction bottle, filled the reservoir, then turned the wheels lock to lock as I watched the reservoir so it didn't run dry. The car was up on jack stands so it was easy-peasy to turn the wheels. .


Going against common wisdom (and being too impatient to wait for the Motul Dex III I ordered to arrive on Friday) I bought a couple liters of PentoFluid EHF, their Dino hydraulic fluid. It's conveniently green, so I knew just when the old red ATF stuff was all gone.


I let the reservoir go almost dry, then I undid the vacuum bottle, unplugged the reservoir and sealed that up. FWIW, I left the reservoir loose from its mount until the end, it's easier to make the connections and tighten the hose clamps with it loose. The hoses hold it well enough to keep it from spilling.


Finished up by cleaning up the little bit if spilled fluid and put the belt back on now that the tensioner was soaked enough to undo the lock nuts. Boy, it's nice to have power steering again. But I'm going to have get back to "Upper Body Day" at the gym.

Partial Post: Please Login or Register to read the full post.

[tejon007]

dlearl476,


When I got my 968, it had paperwork that indicated a "new" steering rack had been installed within the previous 1 or 2 months.


Turns out, it was a refurbished/rebuilt rack installed with hydraulic fluid (if I remember correctly, the green stuff). The rack didn't last all that long. The seals deteriorated and failed.


So, not to criticize or give you heartburn...but, I think using ATF is what the specs call for. When I fixed the rack, I've used ATF without any problems since and for much longer that the original repair.


Best wishes for getting it sorted out.

Partial Post: Please Login or Register to read the full post.

[dlearl476]

I guess I was too impatient. The ATF scheduled to arrive on Friday arrived today. It was always my intention to flush it again when I got the ATF. And using my method and going from green to red will make sure all the Pentosin stuff is out of there.


ps: the fluid I used (Pentofluid EHF) is mineral-based. Id take a WAG that what was in your rack was 11S of 202, both synthetic. (and also green)

Partial Post: Please Login or Register to read the full post.

[MCL968]

Welcome!

 

Waylander in England advises changing the reservoir once in a while since there is a filter screen in the bottom that can't be cleaned, and they are relatively cheap if you buy one for a BMW, which is the exact same unit.

 

Something to consider while you are in there.

 

M-

Partial Post: Please Login or Register to read the full post.

[Waylander]

Please find attached the ZF document on flushing and bleeding your ZF power steering system

 

same from 924-928 all the years all the way through

 

 

ZF-power-steering-flushing-and-bleeding.pdf Size: 397.37 KB  Downloads: 19

 

Tank

 

Meyle 314 632 0000

Partial Post: Please Login or Register to read the full post.

[dlearl476]

Welcome!

 

Waylander in England advises changing the reservoir once in a while since there is a filter screen in the bottom that can't be cleaned, and they are relatively cheap if you buy one for a BMW, which is the exact same unit.

 

Something to consider while you are in there.

 

M-

Ive heard that. I cleaned mine just fine: plugged and filled halfway with Wurth Brake/Parts cleaner. Soaked and sloshed for a minute or two. Rinse and repeat. Third time was the charm.


Cleaner came out as clean as it went in. Forth time with a bit of fluid after sitting in the sun to evaporate any solvent left inside.


ps: Rock Auto sells the Üro reservoir for $11.98.

https://www.rockauto.com/en/catalog/pors...rvoir,7378

Partial Post: Please Login or Register to read the full post.

[dlearl476]

Double post.

Partial Post: Please Login or Register to read the full post.

[dlearl476]

Please find attached the ZF document on flushing and bleeding your ZF power steering system

 

same from 924-928 all the years all the way through

 

 
ZF-power-steering-flushing-and-bleeding.pdf

 

Tank

 

Meyle 314 632 0000[/size]

Thanks for posting that. Saved to iBooks. I looked for an hour with no success. I gues I used the wrong search term. Should have used "ZF" instead of "Porsche 968."


Good to know I did it "mostly" correct. I'll know better when I replace the PentoFluid with ATF. I have to say though, I think the vacuum bottle is a better, and cleaner, plan than running the starter. When I first thought of this plan, I thought of turning the pump by hand, but as I didn't need to prime a new pump (mine was already full) when I saw the fluid coming out simply by vacuum pressure, I bagged it.


One other thing I learned: pee pads. I was going to bring one from home but I forgot. Using one under the reservoir for making and unmaking the reservoir hoses would virtually eliminate any mess.


ps: Final thought on the "turkey baster" method: no matter how many times you suck and replace, you'll never get 100% of the fluid out. I'm sure it's a sufficient method to renew ATF, but when your system is contaminated by synth fluid like mine was, the only way to get it completely clean is the ZF method.


ETA: For future reference, the PS capacity is .7L of fluid. I put just over a liter of fluid through the system until it was running completely green.

Partial Post: Please Login or Register to read the full post.

[dlearl476]

Well, got it all flushed and filled with ATF. I tell ya, the pee pad was genius. Not a single drop spilled on the paint.


Whats weird is going A-B like I did, I have to say that steering effort is 25%-30% heavier with ATF than with the Pentofluid EHF. But Ill sleep better knowing its a) not leaking b ) got the spec fluid in it and c) flushed and filled per manufacturers recommendations. (Thanks again Waylander for linking that pdf.)


Once again, it took just over 1L to flush from green to red, then another ~.2 or so to top up the reservoir per the ZF pdf.


It may have been a waste of 2L of EHF, ($28) but Ill tell you what, after 2 days of running it, it was already a little discolored, so Im patting myself on the back for the foresight of running the lower viscosity fluid in there for a couple of days to further clean the system.

Partial Post: Please Login or Register to read the full post.

[Waylander]

The high pressure hose on my car was collapsed inside in the middle, once I replaced that the steering was light again with the correct ATF

Partial Post: Please Login or Register to read the full post.

[dlearl476]

My steering is still light. Its just a bit heavier with ATF than it was with the EHF. The viscosity of the EHF was noticeably lower than ATF. More like brake fluid than ATF.

Partial Post: Please Login or Register to read the full post.

[ds968]

At one time I contemplated getting rid of the power steering because I like a stronger resistance feel in the steering wheel but 1) even if that was possible, driving in and out of parking lot spaces would require some serious effort, and parallel parking would be a herculean task, so not worth it for a street car.. and 2) I understand that simply disabling the P.S. fluid reservoir won’t achieve that result and could cause serious mechanical / functional problems with the car’s steering . 

Partial Post: Please Login or Register to read the full post.

[dlearl476]

At one time I contemplated getting rid of the power steering because I like a stronger resistance feel in the steering wheel but 1) even if that was possible, driving in and out of parking lot spaces would require some serious effort, and parallel parking would be a herculean task, so not worth it for a street car.. and 2) I understand that simply disabling the P.S. fluid reservoir won’t achieve that result and could cause serious mechanical / functional problems with the car’s steering .

Appraently there's a manual rack for the 944S2. Whether that would work on our cars or not, I don't know. But a guy on the Rennlist said the manual rack is a lot easier to turn than a disabled PS rack.

As for damage? Who knows. I drove mine without the reservoir or a belt for two years. Not much over those two years, maybe 1500 miles. But AFAIK, it didn't suffer any.

Partial Post: Please Login or Register to read the full post.

[ds968]

Interesting .  Not going to bother with the cost and hassle of switching to a 944S2 system ( “rack and pinion” ? ) but I might give the belt-less mode a try for a few days and couple of hundred miles, and see how it feels .  Not sure how easy it is to remove the P.S. belt with a supercharger in the way but I’ll have my very accomplished mechanic buddy take a look at it. 

Partial Post: Please Login or Register to read the full post.

[dlearl476]

We have the same steering as a 944, and a 924. Entire suspension, actually. Based, FWIW, on the VW Jetta/Passat. It's the legacy of the failed Porsche Design for VW's replacement of the Karman Ghia which became the Porsche line of transaxle cars. It's was originally designed by Porsche to be a parts bin sports car for VW, before the Peichs took over and decided VW was going to be a family car company, not a sports car company.


How many parts are interchangible, I don't know.


As for losing your belt, your SC shouldn't interfere. It's done from below. You remove your splitter, if you have one, or batwing, and the front plastic pan. The tensioner is right there. You loosen the pivot bolt, loosen the lock nuts (remember one side is RH threads) and screw the tensioner in.

   

This is a 944 but it's the same thing.

Partial Post: Please Login or Register to read the full post.

[dlearl476]

After thinking on it for a minute, it's easy to understand why a non-powered powered assist rack would be more difficult to turn: in a manual rack there isn't any fluid in there to fight against. Only greased gears.

Partial Post: Please Login or Register to read the full post.

[tejon007]

My '72 & '74 both have manual racks and I wouldn't change them as they work fine, even for parking . I like the way they work. And once you're moving, the effort isn't so bad.


As you know, the 968 has a power rack and I wouldn't change it, except for its tendency to snap oversteer.


However, I've been toying with the idea of adding power brakes to the '74. The manual brakes could stand some improvement and brake pad composition changes aren't the same or enough.

Partial Post: Please Login or Register to read the full post.

[ampegboy1]

Interesting .  Not going to bother with the cost and hassle of switching to a 944S2 system ( “rack and pinion” ? ) but I might give the belt-less mode a try for a few days and couple of hundred miles, and see how it feels .  Not sure how easy it is to remove the P.S. belt with a supercharger in the way but I’ll have my very accomplished mechanic buddy take a look at it. 

 

FWIW, years ago the power steering failed on my dad's old 1993 Passat estate, which weighed about the same as a 968. When the car was moving above about 20mph, the steering with the belt removed was heavy but perfectly usable. Below that though it was barely steerable - OK to get you home in an emergency, but bad enough to warrant fixing ASAP!

 

Michael

Partial Post: Please Login or Register to read the full post.

[ds968]

As for losing your belt, your SC shouldn't interfere. It's done from below. You remove your splitter, if you have one, or batwing (front apron), and the front plastic pan. The tensioner is right there. You loosen the pivot bolt, loosen the lock nuts (remember one side is RH threads) and screw the tensioner in.
image.jpeg

This is a 944 but it's the same thing.

Thanks, but I wasn’t thinking of the SC unit and top components ( brackets, pulleys, piping , etc ) getting in the way , but rather the SC serpentine belt positioning vis-a-vis the power steering belt , or , even more importantly if the SC belt replaced all the others and runs all the pulleys ; AC, P.S., Alternator, etc.   In which case, the P.S. removal out of the equation idea is DOA.    I’ll look at the engine in a few hours ... ( Stupid WebEx meeting starting in about half hour - to accommodate our colleagues in both London and Singapore I have to get up at this ungodly hour .. :whine: ..) 

Partial Post: Please Login or Register to read the full post.

[tejon007]

After thinking on it for a minute, it's easy to understand why a non-powered powered assist rack would be more difficult to turn: in a manual rack there isn't any fluid in there to fight against. Only greased gears.

Personally, I don't think it would be a good idea to pull out my pocket knife and slice off the power steering belt. And, in some cars, that would be quite dangerous due to the effort required to turn the wheels. Anyone ever have the motor die on a '66 Buick Electra 225? Impossible to steer unless you're the Hulk without power steering. ..


There are other factors that go into the effort needed to steer with a manual rack, like steering wheel size (a DAPO replaced the steering wheel on the '74 with a much smaller aftermarket wheel which made it stupid difficult to turn), the mechanical advantage of the rack (i.e ratio of the pinon to the rack - similar to a differential/ rear end that's been laid out flat - think of a 2.31:1 rear-end swapped with a 4.1 for drag racing), the toe in or out, the wheelbase, tire size, front-end/front-end weight bias (I'd even say mid-engine vs, front or rear-engined), etc.

Partial Post: Please Login or Register to read the full post.