92 GTS PSD repair with pics

[SolReaver]

Hey folks, I am working with the PSD system on a 9/92 GTS and thought that I would share a bit of the fun with you. As always...If you have any comments or suggestions jump on in. Let's get started, shall we?

Caveat: PSD system work is NOT for the faint hearted or casual mechanic. DO NOT attempt this if you don't have the skills or experience. You loose no bragging rights and actually gain some points for your wisdom if you let a pro do it. I am not kidding...this is beyond the scope of DIY repair and maintenance. You can get hurt and the hospital bills will likely be more than the money you "saved" on the off chance you get it right.

First you need a car, 90 or above 928 with PSD difficulties. This one is a 92 GTS. Very nice indeed. The original plan is to replace the pump unit and flush the system.



The old system is contaminated. Not going to belabor the point. These things happen.

IF you are doing the job, you should know that the pump assembly is held in with 3 10mm bolts. Two are visible...one is hidden and only accessible if you remove the lower plate below the pump. Here is a picture of the back of the pump to let you see that the nut comes up from below and fastens to a stud on the back of the pump unit.





A little background...This one has a bad pump. Trust me, I checked before taking it out. It is Deader than Ceasar and no use holding a funeral. Out comes the old pump unit and we compare it to the new one to make sure everything is the same.



OK, It all looks good. Just a little bit of a hardware swap for clips and such and install the new Reservoir.





OK, the new unit is in and we bleed the system. I won't bore you with details..Check out the 928 Owners club "PSD Fluid flushing procedures" document by Lois Ott and John Vettinger, who, should be commended for their work as it is a darn good resource.

Everything was going fine until I got to Section IV, "Flush the PSD lock slave cylinder and pressure line": Subsec: # 30, "flush the PSD Slave cylinder" Paragraph: IF you get no fluid from the bleeder fitting, the accumulator may have been empty or the bleeder screw not opened enough.

Well.....No. The bleeder screw was full open and there was plenty of fluid in a working and full accumulator. (I triple checked) So at this point we are off the map so to speak. I disconnected the line at the slave and opened the lock solenoid....Nothing. Uh oh.... A visual on the line showed that it was flexing with the internal pressure and so I disconnected the line at the PSD assembly end. Full pressure, Nice flow....Whew! I was really worried there.

Ok, So we take a logical approach and slice the problem in half. About half way to the Slave is the Regulator. it looks like a fitting, but it is a regulator.



OK, carefully take that apart and inspect. You can never have enough flare nut wrenches.



Another opening of the lock solenoid spewed copious amounts of foul stuff out, Then the line ran clean. From the center point I blew compressed air into both lines and more junk splattered out the slave side. I cleaned the slave side and inspected the slave. It was frozen.



Fine. Be that way. Out comes the slave for a full inspection. Yep...It's junk.



Now that the slave is out, I clean and inspect the transmission bellows. ...once it is clean, I felt around inside with my finger and determined that the bellows or boot is ruptured, so...I am thinking that I will want to open up the Trans axle cover and take a peek in there to check for contamination.



So...Right now, I am thinking replace the Bellows (928 332 051 02), Regulator (928 315 211 03), and slave cylinder (928 332 775 09)

Thanks to Jason at Pelican for the numbers.

[SolReaver]

So, here is what the regulator, line and slave look like:


A better look at the Regulator cleaned up.




I cleaned it out as best I could and It appears to be working correctly, however, at this point IMHO it is best to replace it due to the contamination.

[SolReaver]

The boot or transmission bellows was torn as mentioned before...so...I drained the contaminated fluid and took off the rear trans axle cover plate. the level of contamination is not too bad, it seems that the fluid held it mostly in suspension. To remove the plate, disconnect the passenger side ex pipe at two points, 15mm up front and 13mm bolts at rear. the drain plug(s) and filler plug are 10mm hex. Prep wit pen fluid and lightly wake the pugs worked for me and the plugs didn't present much of a difficulty. The main obstacle is the 8mm banjo bolt holding the transmission fluid line to the upper passenger side of the trans axle cover plate. An 8mm short L hex wrench with a little body english did the trick. I suggest that if there is ANY question of contamination that you perform this procedure to be sure. Even if it turns out that the contamination is minimal, It is a good idea to be able to inspect and thouroughly clean the transmission itself. Details to follow. Here are the pics.


The Glass pickle jar is the contaminated Dot 4 PSD fliud that I recovered. The plastic jugs are the contaminated tranny fluid. Like I said it could be worse. Luckily the fluid was the good stuff and so it chemically neutralized a good deal of the contaminant.


The cover plate like the rest of the transmission has a thin layer of "Ick" but is otherwise good. Note that the gear and pump are in good shape. When removing or installing this cover...be VERY careful that you go STRAIGHT in or out the last half inch or so or else you run the risk of binding or crushing this critical little piece. No pump, no lubrication...you are officially screwed.

THE most expensive Slave cylinder in existence! Don't believe me? Try pricing one. Some day I will figure out how to rebuild this one, just to have an alternative to the high price tag. For now...Soaking in weasel piss for two days has freed it up to the point I can take it apart (later) However...with the part on order and on it's way from happy Deutchland....We are going with new.

That pesky Banjo bolt. Removing it separates the worthy from the unworthy. Note I Did NOT strip or musss it up on removal. A solid seat with a good 8mm L hex is all it takes. You may have to cut down your short leg, depending on the wrench. Mine was already cut down. It seems that these cars are "evolving" my tools.

Not much metal on the magnetic plugs...Looks like we goty here in time and that the tranny has lots of life left in it.

Detail on the pump gear teeth. Ok...It is not riding EXACTLY on center...But, if it was good enough for the factory...it is good enough for me. I will not attempt the whole "adjustment" insanity

The filter screen is also in good shape and clear of nasty debris. Good!

The bevel and surface of the gears is perfect. No pitting or spalling

[tedward515]

Holy $hit, that almost makes me not want a later car!

[Maleficio]

Long time, no see, SolReaver. Great thread.

[SolReaver]

Thanks Malifico...Yea, as you can tell, I have been busy. The thread evolves as I add material, check back every so often. I updated the photos with captions.
TedWard515: Don't make any judgments, These things are SWEET. Like any 928, there are issues and the PSD system IS complex. But, in the end it is just a matter of time and money. Besides, this one in particular is a real beaut and well worth the effort.

OK, More Pics!


The junk flung out from the PSD clutch to the front of the case...


And up to the top and sides.


Did I post this pic already?

[SolReaver]

More flung goop. Note the banjo fitting peeking down, It is a good idea to "loosen" the line at the front of the trans to allow you some elbow room when you take the plate off, other wise, you might cock it up and...did I mention how screwed you would be?




A little side view, note the PSD adjuster. It is the bolt with a lock nut under and behind the Halfshaft. DO NOT touch it. There is a specific adjustment that you can make IF you really know what you are doing. However...MOST of the time you are better off leaving it the hec alone.

[tedward515]

Not a judgement, I just didn't know that the PSD was quite so complex. I love learning about anything automotive, especially Porsche related. Keep up the good work.

[SolReaver]

Back to the project. There is a lot of cleaning that has occurred in the meantime. I removed the old bellows by butchering a conventional seal puller. There is almost no room to work with and it was a bit tricky.

659- clean and lightly lube the threads in the case and apply a thin coat of sealant to the mating surface.



660- Clean



661- Looks good



662-



663



664- install the new bellows and new slave. Note the factory paint on the bolts. hmmmm, red.



funny, the PET lists the bolts as as allen head, these are conventional 13mm. Not that it matters a lot.

[SolReaver]

more pics...


667- a thin, and I meant thin coat of sealant on both mating surfaces. you don't really need it. the paper gasket is good enough and the surfaces are precision machined, I just like to be thorough.

set the paper gasket on lightly and align while the sealant is setting.

clean the lines while you are waiting and prep the threads with anti sieze and a little thread sealer.

lightly press down the paper gasket and check for alignment.


clean and check the hardware. 12 bolts and 12 washers. you can count them if you want to.

673 prep bolts with assembly lube.

[SolReaver]

674- Remember, the cover goes straight on for the last 1/2 inch. the positioning pins will help you out ffrom there. IF you have prepped it all correctly it will go together much better and faster.

walk the cover on, you don't need to use force, just tighten the bolts and it sets itself. loosely set the bolts and give the sealant time to dry before torquing the cover

675


new regulator in. Remove clip, tighten lines from pump to PSD slave. Note that there is just a bit of weak sealant on the threads.

676


extra PSD slave pic



the paint on the rear cover bolts was green. Fascinating.



Note a SMALL bead of sealant after torquing the cover. Just right IMHO.

[stepson]

Great job Sol

[SolReaver]

Install transmission line Banjo bolt
hook up exhaust
install PSD pump shelf
top off PSD fluid.
Fill transmission with fluid (75/90 GL 5 spec)
tighten fill plug.
Put the rear wheels on (red stud on hub is for wheel lock opposite the air valve per users manual) and torque nuts.
Test as follows: with car rear end still jacked up, start engine and put into gear. (forward AND reverse works) the car will sense that the rear wheel is turning and engage the PSD. The green light will come on and if you listen you can even hear it actuate. At this point the PSD warning finally went away for good. I didn't have to clear the memory and so I didn't.
Brought the car down and test drove in the rain. The first few activations were a bit sluggish, but by the 5th or 6th time it was operating flawlessly.
Re torqued the lug nuts (one HAD loosened, good thing I check, huh?)

Turn over to owner who is a happy camper.

[SolReaver]

Thanks Stepson, It was a tough job but I am very happy with the end result. There is not a whole lot of information out there about actually working on PSD and I thought this could be useful. Check back later (a few days) as I am editing the thread currently.