FredR

Went into the PSD area today for a dry run to suss out any potential difficulties- found a few-

1. I intend to followed Louie's procedure so made a simplified check point list.
2. Had no problems removing the shield- seems it was not there! There is a cover plate at the front and the rear and two brackets in the top that were not holding anything so I presume the often talked about NLA shield is missing. Removed the rear plate to reveal the PSD unit and blasted it with air then washed everything with soapy water- came up nice and clean.
3. Getting the solenoid valve bleed nipple undone may be a bit tricky as there is very little room. Managed to get a 11mm 1/4 drive socket on the nut but so little room to turn it. I have some 11mm ring and open ended spanners but again whether they will get the nut remains to be seen.
4. Pouring in brake fluid may be a bit tricky- I think the best way is to have a little pump of some kind but I reckon brake fluid can be decanted directly as long as it is poured from a half empty bottle.
5. The electrical connections looked good both in the PSD compartment and the trunk- of course that does not mean they have 100% integrity.
6. The bleed nipple behind the diff looks a bit tricky to get at- may have to undo the bolts holding the half shaft to the diff and let the shaft drop down- may make life easier.

Other than the above it does not look too bad. I am always a bit apprehensive the first time I try a procedure new to me.

Rgds

Fred

worf928

What procedure are you trying to do? The OC bleed procedure by Ott and Veninger?

There's nothing that needs unbolting. You can get to the slave cylinder bleeder with a closed-end 7mm and fingers. The cap on the accumulator bleeder needs long needle nose pliers.

worf928

Fluid is best done with a Motive bleeder setup.

John Speake

If it turns out to be the acceleration sensor then I supply fully solid state ones...

http://www.jdsporsche.com/Lateral%20...%20sensor.html

FredR

Dave,

That is the procedure I am following.

My comments are based on first impressions flat on my back in 35C heat this afternoon so I may well be too conservative. It seemed to me that there is access to the 7mm bleed nipple but I could not see it "direct line of sight" and that put me off a bit.

I purchased some new safety goggles- hopefully they will not be needed but just in case given the potential pressures involved [albeit such should not be present]. A Max jax would be perfect- just have to manage wiith what I have at the moment.

Apart from safety, my main concern is to avoid contamination of the reservoir. Hopefully I will be laughing about this by tomorrow evening. One of those power bleeder kits is on my wish list.

Rgds

Fred

FredR

Well the saga continues- no smiles at the moment! I like Dave's suggestion to use a pressure bleeder so have been looking into that but earliest I will see anything out here will be two weeks.

Although somewhat hot today I ventured into the garage late afternoon to see what I could do today. Figured at the least I would see if I could undo the 11mm bleed nipple on the PSD unit. Donned my safety goggles- tried with the 11mm socket but no travel possible. Tried with both a combination spanner and a ring spanner but could not get the thing to budge- it seemed as though as I put tension on the spanner the rubber mount was deforming leaving me with no where to go with the spanner up against the side of the main cylinder under tension. Now looking to see if I can arrest that movement with a wedge or something.

Interestingly before doing this I pulled my spare PSD unit from the late S4 out of its drawer and tried to undo the bleed to get a feel for how much torque might be needed- hardly moved the thing when there was a gush of brake fluid came out albeit with little angular movement- fortunately it missed the front of the 928- that after being sat for nigh on 12 years and having been disconnected/removed from the car. I was prepared for such happening but did not really expect to see this.

Now back to scratching my head again. Maybe I can get a bit more clearance using the open end of the combination spanner but I do not like using open enders on things that appear "stuck" or difficult. Invariably I am going to lose some knuckle skin- I feel it in my water!

FredR

Quick update: after last post went into it again and decided to have a go at the nipple with an open ender that at least gave me some good purchase angle, slipped a bleed tube over the nipple into a catch jar- was able to get some reasonable torque onto the nipple and it felt as though the stiction had broken but sadly I must have had the thing slightly off line and the movement was ******* the corner of the flats [why I do not like open enders]. Tried again - plenty of torque but still no joy.

Cannot believe a small nipple like this is wedged in there so tight and its is not that long since I had the main agents change the fluid [about 2.5 years]. Those bleed nipples should need little more than a nudge to seat them.

If all else fails I may have to de-mount the unit for better access but such should not be necessary. Must enquire as to which gorilla tightened the bloody thing like that.

worf928

I've decided that most invoices for PSD flushes are bogus. That's why I started turning my own wrenches 20 years ago: I performed an experiment with the result that I was charged for a PSD flush that didn't happen.

In any case, I put an 11mm boxed/closed-end on the bleed nipple then slip the tube for the bottle over the nipple.

Make SURE you are lefty-loosey righty-tighty; It's easy to get turned-around when you are trying to wedge an arm and half of your head in there.

Whatever you do, do not loosen that accumulator bleeder without the bleeder tube attached. Do. Not.

The 7mm on the slave cylinder is mostly by feel and inspection mirror (the first time.) Same deal though: 12pt, 7mm box-end on the bleeder, then bleeder tube. You can slip the wrench past the hex part of the bleeder to rotate to the next flat without needing to remove the bleeder bottle tube.

FredR

Hi Dave,

Thanks for the continued support- much appreciated. I well learned the lesson about the bleed nipple on my spare unit [ahem] after it spat a gob full of brake fluid on my garage floor! The maintenance manager at the main dealers is a good friend of mine and I am sure he would have seen to it that my jobs are done but I would think that many unscrupulous dealers would do as you say.

The good news is that just as you suggest, I placed the tubing over the nipple last night and decided that sh*t or bust it was going to be loosened- I tugged on the 11mm open ender for all I was worth [not that much these days] and it cracked open- the good news was the fluid that came out initially was nice and clear- I nipped the thing back up and left it. I am thinking to acquire a pressure bleeder kit like you suggested.

Hopefully the 7mm nipple will put up less of a fight but .....?

Unfortunately the hot weather has returned somewhat prematurely- it was 42C mid afternoon yesterday [urrrgh] but at least it cooled off nicely early evening. I like to get my jobs done before this happens. Hopefully I will soon have an a/c unit in the garage!

Rgds

Fred

FredR

Tried exactly as per above in a dry run this evening. Easy to feel everything even though one is blind. However I could not seem to find a position where I would be able to get some movement- grrr!

Will take another look tomorrow

NoVector

Hi Fred - That's a crappy job--very cramped and little clearance. FWIW - bleeding those two valves are the only reason I bought a set of flare nut wrenches (also called tube or line wrenches). It's sooooo much easier and conducive to having the bleeder tube on the nipple.

The pictures and instructions in this thread may help: https://rennlist.com/forums/928-foru...procedure.html The last picture of my post #8 has the slave cylinder so you can see what you're aiming at.

I use small brake fluid bottles and lay a towel on the tray underneath the PSD when filling just in case of drips. I could see how a Motive power bleeder would work, but I don't know if it's worth the 2-week wait in your case.

FredR

Thanks for the thoughts- your note prompted me to take a look in another bag of spanners that I rarely use and found a shorter 7mm wrench than the one I was trying with today that snagged on te petrol tank one way and would not fit in the other way.

Obviously it is a "dooable" job but yet again everything seems to be in the way. Dropping the exhaust and undoing the half shaft flange to let the shaft drop out of the way would at least give line of sight but it seems as though such would not improve wrench access.

Doing the job from axle stands does not help and just to add fun to the job I had a nitrogen freezing procedure on one of my left knuckles last week to remove a veruca and that is a bit fleshy at the moment and this task would be impossible with gloves on.

Don't you just love these cars!

Strosek Ultra

Fred, when doing the red car I loosened the drive shaft in order to get better access to the 7mm nipple at the slave cylinder.
I used a Mityvac handpump to fill the fluid container.
If air is in the PSD-system priming of the system can be kind of tricky as mentioned on this forum before. The suction function of the pump is very limited making it difficult to get the fluid into the system. The Workshop Manual tells you to put some air pressure 1,5 to 2,0 bar (22 to 29 psi) into the top of the fluid container.
I tried another method which worked very good. Connecting a Mityvac vacuum-pump to the bleeder valve on the locking solenoid, the vacuum immediately made the fluid to enter/prime the system. When the system was primed the flushing/bleeding procedure was no trouble at all to perform.
Åke

FredR

Åke,

In theory at least my system is primed- all I have done to date is open the bleed valve on the PSD unit and allowed a little fluid to flow out for test purposes [it was nice and clear]- I presume this does not allow air into the system but maybe I should have had the end of the pipe dipped into some fluid.

Once I have cracked the slave bleed nipple I will then proceed with the job. I did note your use of the Mityvac to suck on the system in the other thread- I have such but unfortunately the little bottle that comes with the kit has failed and I need to replace it somehow- needs a little bit of lateral thinking- maybe a length of tubing will be enough to prime the system should it need it.

I assume the system from the PSD unit to the slave cylinder is dead ended with the pressure being released when the solenoid power is off.

worf928

Correct.