steering rack PS fluid

[brian in buddina]

I saw this comment recently come up on the 968 Enthusiast fb page. I haven’t heard of this being discussed here before, but can relate as I have a leak somewhere on my power steering rack or associated hoses. So finding my leak is a future project. As per my 1988 944S published driver’s  manual I am using “ATF Dextron”. My latest purchase is Bursons type DX3 ATF which says on the container: “ all vehicles requiring Dextron fluid”

The question to the brain trust is; has anyone switched to the Pentosin?

Has this had any effect on reducing your PS leakage?

In regards to the mentioned “low ambient temperature” I am in Queensland so this would not effect me.

  

 

When it comes time to pull my power steering rack and find my leak, is there a kit with new seals available which don’t break down with ATF Dextron?

I’m assuming the 968 power steering rack is the same, or very similar to the 944 one.

thank you.

 

 

 

[Fishcop]

I am absolutely no expert on 944 power steering systems.  But I have noted that a lot of 944 owners seem to have just taken the unit out and given it to a power steering specialist - apparently they are generic German, and a VW/BMW/Audi type pro will have it reconditioned and back out the door to you in a day or two.  Given it's a pretty vital system I personally would take this route for peace of mind...

[TINGY]

I have never had a leaking rack on any 944 I have had and in all the books that have come with the cars I have owned, all racks were reconditioned at some point by a pro shop. Looks like to me if it is done correctly it will last a long time.

[brian in buddina]

@Buchanan Automotive

Bruce or Sean 

Are you aware of any Porsche maintenance revision to the power steering fluid?

thanks 

Brian

[Buchanan Automotive]

The 944 series with ZF hydraulic power steering( in R / H / D ) became available in 1984 as an expensive option( rare option for 1984 )  & then in 1985 ( R / H / D ) as standard and it stayed that way from that point on , including the 951 / 944S / 944S2 / 968 etc , in all those years the factory fill was ATF ( Auto Trans Fluid )

Note } In regards to the 944  R/H/D version , the power steering rack changed with time , there are three different racks used ( all are ZF ) and all are very similar ( except the first version ) , but as the years went by the  design of the racks changed , most notably the 1985 & 1985 R / H / D racks are quite different to the 1987 > versions , meaning the aluminium pinion housing is very different and some of the internal seals are quite unique plus other changes to the 1985 & 1986 versions 

Note 2 } In R/H/D the 944 was not available with power steering in the 1982 & 1983 year models , however saying that in the last 20 + years Sean & I have retro fitted at least 6 or 7 early R/H/D 944 with the later R/H/D ZF power steering systems , makes the car a way lot better to drive in every area imaginable  

Note 3 } A really nice thing that Porsche installed in regards to the 944 power steering systems was a seperate stand alone power steering oil cooler in the air flow in all the year models ( this became very important as the years / decades went by )

Note 4 } The deep last century 944 power steering rack , be it R/H/D or the quite different L/H/D were designed to be dismantled and repaired ( no hidden internal circlips etc that the much later 993 steering rack received )


Note 5 } All hydraulic power steering rack/s ( all types and all versions on all cars , just a matter of time and heat cycles) ) will eventually leak fluid , its interesting ( as a side note ) that the high pressures the 944 racks have to deal with , its amazing they do not leak more often & yes we have repaired dozens of leaking 944 ( R/H/D ) power steering racks over the last 28 to 30 years 

Note 6 } The R/H/D 944 power steering racks are much rarer ( less made ) than the more common and completely different L/H/D racks 

Note 7 } The enemy in regards to the life span of a hydraulic steering rack is a torn steering rack boot ( 2 in total ) & when this happens ( no warning at all to the driver ) water and dirt will get inside the rack , in regards to water it will rust the crap out of the main internal ( polished steel) steering rack shaft & when that happens the rack is usually scrapped and the owner has to find another 2nd hand one ( similar type ) and hope like hell we can make one good rack out of the two of them 

Note 8 } The other enemy is the power steering oil( ATF ) changing colour from a nice red colour to a dirty brown colour , this is caused by time , but mainly excessive heat & this is the secret behind the 944 power steering long life , its the cooling of the power steering fluid , but that said , the fluid ( holds very little ) should be changed every 5 years or so anyway , but its often out of sight and out of mind and we regularly see a 944 / 951 / 944S2 / 968 that the power steering fluid is quite discoloured & thats because no one has every changed it or has not been changed for 20 years etc  , its all quite simple , but like I mentioned its the stand alone oil cooler that was a nice touch & even more interesting is that at the same time Porsche did NOT install power steering ( stand alone ) oil coolers to their more expensive cars ( weird ) , but that was mainly a lack of space thing in those more expensive cars
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 The 928 series ( 1978-1995 ) , the R/H/D  928 dedicated ZF power steering systems , the much larger ( unique ) 928 power steering rack ( as compared to the 944 rack ) is / was beautifully made & made to be dismantled and repaired ( no hidden internal circlips etc ) , but was in need of a stand alone oil cooler ( 1978 -1986 ) because the ATF oil would discolour a bit more quickly ( V8 heat in a small engine bay ) & when I mean discolour I mean a dirty brown colour & when that happens it smells off as well & it then becomes a very poor lubricant , now I do not mean that the 928 power steering oil ( ATF ) needed changing every year ( not at all ) , but I used to inspect the colour of the power steer oil in these cars when servicing them back at the Sydney Porsche dealership I worked at from 1977 to 1994 & in the 1980's I noticed that if these 928 cars were used in heavy stop start ( typical Sydney traffic ) and in the hottest weather year after year ( remember these cars had a fantastic easy to use automatic transmission that was easy to use even in the worst traffic ) and it was these cars that I noticed the ATF going off , easy to fix , just change the fluid , easy to do and extremely inexpensive 

Note } Porsche must of noticed to because when they introduced the 928S4 model ( 1987 ) these cars now came with a stand alone power steering oil cooler in the nose cone ( just like the 944 series ) & naturally it stayed there for the model years 1987 - 1995 , but that said I would still change the ATF ( power steer fluid ) every 5 or so years ( give or take ) and its was so cheap to do I often didn't even charge for it during a major service 

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964  ( 911 series 1990 to 1994 )  , these had a unique ZF power steering system , unique rack ( be it L/H/D or R/H/D ) to any other Porsche a power steering pump that was mounted way back in the engine bay driven by a tooth belt from the rear of one of the camshafts ( nice packaging ) but quite difficult to work on or get at compared to the front engined Porsche's , but there was no choice it had to go somewhere in the engine bay & it had to be driven by the engine , so it is what it is .    But it gets way way too hot back there & more interestingly is there is NO power steering oil cooler at all ( nothing ) even the power steering rack is mounted up high above the front subframe area ( nice packaging ) but its completely out of the airflow when all the front under trays are in place & the power steering pipes and hoses to & from the rear of the engine to the front of the engine are all hidden away ( nice packaging by Porsche ) , but the power steering system gets bloody HOT and you can see it with the 964 & the 993 ( similar system with some small changes ) the power steering oil discolours the quickest out of all the Porsches I have mentioned so far , we have seen 993's and 964's ( for the first time ) and the power steering fluid was BLACK and it stunk , this once clean fluid has been overheated time and time again & none ever knew or suspected it , these ones need the fluid system flushed & even then the new ATF fluid goes off dark brown / black within days because the amount of burnt oil deposits etc coming away from where they were stuck inside the rack , pump hoses and pipes and now the new oil is capturing these deposits ( thats what new oil does ) , so in the worst cases we have had to change the oil many times over the following few months , this is cause by lack of power steering oil changes and the lack of oil cooling 

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Note 9 } The ZF power steering racks installed in the R/H/D ( probably l/H/D as well) 993 series had the " beginning " of un- repairability built into them by having some internal of rack circlips( with NO eyelets to being able to remove with circle pliers ) that once installed by ZF were designed to not be able to be removed ( not a good sign ) but you can get around it with some clever thinking , but it was the start of cost cutting and it never ever stopped ( but thats another subject for another time ) 

Now we go to the Pentosin Fluid , from 1995 year model the 993 ( all versions with ZF power steering ) was filled with the early version of the Pentosin fluid , but over the last 25 years we have come across heaps of 993's with just ATF in the power steering system , this is very common with humans , 99% of humans around Australia with a 993 will / have experienced a leak ( mild or worse from the pump / rack or a hose ) and they are in a place( 3 or 4 hours drive from home on the country road somewhere ) where there is no Pentosin available where they are stuck with a noisy power steering ,( but the local service station has plenty of ATF in bottles ) & the owner has heard on the grape vine ( be it internet of a Porsche club previously that ATF fluid will work OK ) & if they can top it up with something to save a $ 800 tow home and the massive inconvenience of it all , they will buy a 1 litre bottle or two of ATF and whack it in to get home  & keep topping it up on the long journey home , I do not blame them one bit & because it worked fine , from that time on ( once the leak was fixed ) the the owner could clearly see the price difference between Pentosin and just normal easy to get ATF , the owners got a real dislike for this Pentosin , so hence you see lots and lots of 993 's with ATF , it works fine if you keep the power steering oil changes regular , so in a 993 thats used a lot in a built up area ( more engine bay heat ) we would change it ( say ) every two years or so & its fine 

Note 10 }   Over the last 3 + decades I lost count the number of times of having ( over the phone ) instructed an owner of a 944 or a 928 could just cut ( yes cut with a blade ) the power steering pump V belt if they encounter a power steering oil leak way way from home & yes the seperate V belt driving the pump was accessible by just opening the front lid ( bonnet ) , this way the power steering pump will no longer work & hence no power steering oil pressure & you could just drive the said 944 or 928 as long as you like , it just means you have heavy steering  , but you will certainly make it home & or to the workshop etc in you're own time with no expense or inconvenience , but the with the 964 & the 993 the power steering pump is driven by a toothed belt that is completely shrouded at the rear of the engine ( meaning at the back of the engine bay ) and on the side of the road you can not simply cut this belt and then remove its remains to stop the pump from turning , so if the leak is a bad one ( this is always possible with high pressure power steering ) the 964 or 993 has to be flat bedded ( towed ) away 
 

So the question is does Pentosin stand up to the excessive heat in the system better over time ?   ( yes it probably does ) , but by how much ?   , no idea 

Have we seen Pentosin turn to crap ( discoloured ) because its been left in too long in a 993 ? = many times , but because we have never seen this particular 993 before we have nothing to go by except its ( the fluid ) turned to a smelly mess , so obviously its been through hell and has not been changed , thats bad luck for that power steering system 

Its one of the quirky things I go looking for when we see a Porsche , be it a 944 / 928 / 964 / 993 for the first time , just how many fluids are in bad shape within that particular Porsche , the colour of the power steering fluid is the one that just about everyone just forgets about until it bites them in the wallet , remember changing the fluid regularly is CHEAP 

So thats why we give owners of 964's and 993 's the choice of Pentosin or ATF and what it means , and prices & they can choose for themselves 

As for installing Pentosin in the 944 or 928 series , you can if you like , but there is no need at all , just keep the system clean internal ( change the  power steering oil like we have been doing for decades ) and as importantly keep good care of the rack boots , meaning change them regularly & pack some clean grease ( just normal HT bearing grease ) inside the rack ( both sides ) when changing the boots , remember this area is the non power assisted area of the rack and it needs some grease as lubrication on the rack shaft and on the rack teeth to keep wear down & like I said if water gets into this are its never a good result , that applies to pretty much all hydraulic power steering racks 

Regards

Bruce Buchanan
Buchanan Automotive 

[G5032]

What a read!

thanks for sharing all your knowledge Bruce it’s much appreciated

I wish your workshop was in Melbourne!!

[brian in buddina]

Thank you Bruce 

Its very much appreciated for your time to write an answer in such depth!