FredR

Well not withstanding the a/c issues of other listers I have been having to deal with my a/c issues during my annual r/r programme that I stupidly left a bit late in the season- day temps have climbed rapidly albeit cooled off a bit last couple of days.

So, I had to pull the compressor and get it resealed- done and tested well in the shop who worked on it. I took advice of what to do about compressor oil and figured I would blow out the system and flush as best I can and thus start with a fresh charge of oil. To do that I have to get the expansion valve[s] out. I dread this as the last one I tried to undo [on my late S4] I could not get undone despite having the hvac system out of the car [after it was wrecked].

In the car there is little room to work with and my long radius alan key got the single bolt that holds the front retention plate but I could not get either of the two smaller bolts holding the rear plate. Much appreciate any suggestions as to how to get these without rounding the damm things.

If push comes to shove I will leave the expansion valve as is [it was working ok best I could tell] and fit new seals. I may also consider trying to make a hole in the bakellite plate between the two lines to get direct line of sight with my socket set extension so as to get better torsion on the bolt.

Also, although a GTS chassis, it is an early one kitted out as R12 originally. When I pulled the cover off the expansion valve I found the current seals were black. I understood this model year was upgraded with the green type seals in the ac system- any comment? They looked quite OK.

Fred

dr bob

Fred --

You lost me on the removal problem. The one in my 1989 US car has two 6mm Allen-head capscrews that pass through the front plate, pass through the valve body, and thread into the rear plate. Tightening the two screws evenly keeps all 4 connections tight to the o-rings in the valve recesses. I don't remember any screws from the backside. There's a blind threaded hole in the valve body front, but none in the rear when installed. (The spare I'm looking at is the genuine Porsche part from my spares bin.) I use an extended straight Allen driver, with the key insert cut off so the ratchet fits behind the firewall and a straight look at the bolt heads.

Remove the air cleaner box so you can remove the hold-downs where the fuel cooler attaches to the firewall. This lets the engine bay lines move far enough forward to get the expansion valve out without having to pry on the piping. It's a bit of a chore, but you'll likely want to replace the o-rings for the suction line at the fuel cooler too. They are as wrong, old and crispy as the ones in the expansion valve.

FredR

Bob,

For the life in me I cannot think why my setup was not done in the manner you describe but that is just not the case. There is one 5mm Allen head that secures the compression flange to the expansion valve body that locks the two lines to the expansion valve. Once that flange is pulled back, the two pipes can move a bit, the flange can be rotated and that exposes the two small 3mm Allen head screw- this is a DF stupid setup and it was identical on my late 90 S4.

The part of the firewall they cross through has what looks like a bakelite gland plate that the pipes cross through- the plate has 4 bolts but undoing them does not get it out of the way. Indeed mine was falling to pieces so I am thinking of trashing it so that I can get line of sight between the two pipes to give me a fighting change of getting the small allen head screws with my 1/4 drive ratchet with an extension. With my ratchet and the 3mm socket attached there is just not enough clearance to get the assembly in there- urrgh!

The refrigerant feed line [small] has sufficient float to change out the seal. I undid the big union on the gas return line to the compressor adjacent to the cooler [the seal was in excellent condition] and undid the support bracket. I also figured to remove the cooler altogether but I could not get the union on the hard piped connection that takes cooled fuel to the engine. The fuel inlet connection I have had off previously when I did the fuel lines.

I also undid the cable tidy clamp that holds the various cables to give some more room.

If those small 3mm allen head screw were to round I would then have to drill them out- heaven forbid!

worf928

Picture. Nothing you describe seems non-stock. What exactly is the problem?

FredR

The expansion valve on my current [early] GTS equipped as R12 if fastened from both the front and the rear. The front flange has a single 5mm allen screw, undo this, the flange rotates and both pipes can be pulled back slightly. More work has to be done to get the pipes further back to get the seals out and ultimately take the next step to release the rear flange and thus remove the expansion valve. The next step is to undo two 3mm allen head screws. I have a good quality long arm allen key set and i have 1/4 drive sockets with the allen key heads. I cannot get the socket in at the moment as there is not enough head room, I can get the allen key on but if I apply any more torque than I am currently I am sure it will round off.

worf928

You describe the expansion valve bolted from the *rear* not the usual with socket head bolts behind the plate on the front?

There are no threads on the expansion valve front side. It’s the rear plate that is threaded. Impossible is Wwhat you describe.

Obviously, this can’t be the case.

Or do you just describe difficulty in getting a tool square on the two Alan socket head bolts that fix the valve to the rear plate?

If this, then you need a ratcheting bit driver:


If not, and the issue is that the bolts are over-torqued, then...

... if all the normal approaches for a stuck bolt don’t work,

buy a Dremel with the right angle adaptor. Use the medium-size grinding stone.

That, I will add, is SUPER fun...

worf928

Ah. This—^ is the problem. All before was distraction.

Those 3mm are tougher than you think. Nevertheless, apply penetrant, heat, lather, rinse repeat. Make sure the socket head is clean and the bit fully seated. Last remember that a force impulse, a ‘quick snap’ (i.e. pretending to be a human impact driver) is far more effective than applying torque in a gradually increasing fashion.

The Dremel does work though.

FredR

Not sure if my description is flawed but to try and be a bit clearer:

The front flange is pulled into the body of the expansion valve by one 5mm ALLEN screw- that compresses the feed and return lines into the body of the expansion valve to form a seal. For the union of the expansion valve to the evaporator that seal is made by two 3mm allen screws that run through the body of the expansion valve and the heads of these screws sits in the recessed detente of the valve body, they screw into the tensioning flange at the rear. Tighten those up seals the joint by pulling the expansion valve onto the evaporator lines.

Jim Devine

Perhaps this might help-

http://www.nichols.nu/ExpansionValve.pdf

merchauser

FWIW: that is exactly how my expansion valve is fitted.. those 3mm allen screws/bolts were a PITA and I replaced them with cap head bolts from ace hardware with a 5mm hex. the heads fit properly within the recess of the expansion valve

FredR

Jim,

That pretty much describes what I did. I also undid the union connector to the fuel cooler. I see from PET that the RH drive variants actually have a union on the evaporator side of the cooler- that makes sense.

Just remembered that I have a smaller mini ratchet kit that might give me more controlled torque on the 3mm allen screws- I'll give that a crack tomorrow.

FredR

The micro wrench I successfully used.
Got the little buggers this morning!

Dave's post reminded me of a little micro socket set that I have but had plumb forgotten about. The 3mm socket seemed to get a deeper engagement of the screw allen head.

Getting the expansion valve out was facilitated by undoing the union on the inlet to fuel cooler. Why oh why they did not put one on the outlet of the cooler I guess we will never know but most likely [not unreasonably] they wanted to minimise the number of joints.

Now another possible dilemma comes to light- I was under the impression that they solved sealing issues by fitting the green coloured O rings. For whatever reason I had it in my head that they fitted these from 1990 model year onwards. The expansion valve and the cooler union both had black coloured rings in them. I have had no issues with joints leaking but then I must assume that most if not all the rings are the black type units and that they date back to 1992. My instincts are telling me to change the job lot whilst I am in there.

Ironically the boxes of seals available on the local market are close but not exactly the same size according to the data I have recovered on various websites whilst trying to find data about the sizes that seems to be non existent in the WSM- urrrgh! I figured they must be made to standard sizes [whatever the std is] and I should be able to get them locally. I figured they would be metric thus have nice round numbers in metric units but that is not the case and I saw some data for the various unions in the WSM that suggest those are made in Imperial sizes of some kind! Also the locally available rings although rated for 134a are coloured black- double aaaaarrrgh!.

Any suitable inputs appreciated. No wonder so many examples end up with the a/c ripped out- that is the last thing I need over here!

worf928

Getting your tool as deep as possible into the socket is important for good performance.

They did. Until mid-way in MY'87.

In The States, r134 o-rings are green. IIRC, as of MY'93 the o-rings should be green from the factory.

I can't help you on the sizes. I've tried various replacements for the o-rings and they don't work well if they are not exactly the correct size. And since I've not mastered the art of measuring rubber o-rings with an accuracy of 0.1mm I always order them by part number from one of our vendors.

FredR

Dave,

That sounds more like a Stormy quote!

Thanks for the inputs. I managed to get another set of O rings this morning - they are green. I figure that the dimensions are "psuedo metricised" in that they start out in Imperial sizes and use a metric notation thus a little variance in the numbers quoted. Just done a bit of cross checking and visually I had no problem matching size for size on the joints I have currently split apart. Trying to measure them with a vernier caliper is interesting but not really conclusive. To the resolution I was able to achieve they seem identically matched to date.

The Forgotten On

Auto atlanta lists the sizes in their charts found here http://www.autoatlanta.com/porsche-p..._928_parts.php

If anything their site is a great way to access PET effectively and find part numbers quickly just about anywhere.