WUR question (are they full of ... ?)

tabasco · 12-07-2009, 08:14 PM

Hello y'all,

This is on a '76 Carrera 3.0, WUR number ends with "017".

I replaced the fuel line from the FD to the WUR, and since the fitting on the WUR was a bit rusty, the new line was leaking.
I decided to disassemble the WUR to clean the fitting properly, on the workbench.

So I removed the WUR from the car, and while I was in there, thought I would look inside.
I removed the 4 screws and, as I cracked it open I made a mess on the floor with what seemed to be either gas or oil, or a mix of both.
Not sure what it was, it felt thicker than gas, it is a bit slippery, does not seem to dry quick like gas...
The whole WUR smells gas anyway, plus I just cleaned the carb of a lawn mower before so it's hard to tell what was in there.

The chamber with the heating element was full of that stuff. I did not expect anything in there, except air.

My understanding is that the bottom part is connected to the vacuum, and the middle section with the heating element
is maybe atmospheric pressure or another vacuum level, not sure.
The gas stays at the very top of the WUR, above the membrane.
Am I wrong ?

So does that mean that the thin membrane is broken, and it allowed the gas to enter the WUR ?
Or did it suck oil from vacuum lines ?
I've not removed the heating element nor the membrane.

What should I do next ?
And while I'm in there, does anybody know the pressures for this WUR ?
I'll need them soon.

Car runs not very well for many reasons, this could be one of them maybe ?

-Guillaume

Ray_G · Ray_G's Garage

I just went through this. This is the pressure chart for the 76 model, I have the same WUR number as you. Mine was WAY out of adjustment. It makes all the difference in the world to get them set up right. There should be no crud in the middle or bottom of the WUR. (Well, mine had some dirt, but not filled up with muck.) They are vacuum operated, and I have no idea where the crud from yours came from. I am absolutely no expert on CIS, but properly working, and adjusted WUR's make the car a different animal all together. You will need to buy a set of gauges to test the system with. There is more info here:
CIS Primer for the Porsche 911
Good luck!

T77911S · 12-08-2009, 05:10 AM

there should not be anything in there as you thought. one line is vacuum and the other is to atmosphere. i do not know about the 017 WUR. for the 2.7 cars, vac was on top until 78.

how many miles are on the engine? the reason i ask is, if your engine is tired, like mine, you will start to get oil blow by past the rings, out the engine case and back into the intake. my decel valve was full of oil. if your diaphragm in the WUR is bad, it could be sucking oil into the WUR through the vent hose if it is connected to the breather near where the hose from the oil tank is connected. i would get a hand held vacuum pump and pull a vac on the WUR and see if it holds.
the only other thing i can think of is if the metal diaphragm has/had a small leak, maybe the gas sat in there long enough to turn back into sludge.

this is a stretch, but i cant think of any other way oil/gas can get in there.

if the diaphragm in the WUR is bad, i would think you would see some performance problems, unless maybe it was a smal leak, but then you would start to run rich early in the RPM range.

john walker's workshop · 12-08-2009, 06:42 AM

probably from vapors in the vacuum lines over time. 914 pressure sensors often had a lot of oil in them. they just had a vacuum hose to the throttle body.

ossiblue · 09:27 AM

As all have said, there should be nothing in there except air, and certainly not in the quantities you describe.

The "membrane" you mention in the fuel part of the wur is thin, but it is a metal disc and not likely leaking--though that's still possible. It could be the 0-ring seal that keeps the upper and lower halves of the chamber together. Can you see any traces of gas eminating from the round plug that contains the pressure disc?

Remove the arm with the electrical heat from the pin and remove the four small slot-head screws from the bottom of the round plug. Carefully remove the bottom half and the disk and you will see there is nothing much in there except the holes for the fuel inlet/outlet. Clean all things and inspect the 0-ring that seals the two halves. You may wish to replace the seal as a matter of rebuilding.

tabasco · 12-08-2009, 10:46 AM

Ray, thanks for the graph.
I already have the pressure gauge from our host, but have not used it yet.

T77911S : The odo shows 191,000 kms so roughly 120K miles (but it may have more).
I did a leakdown test which showed really good numbers, and unless I did not do it properly, I had <5% on all cylinders, all coming from the rings.
Anyway, good rings or not, I've had oil in the intake before. And quite a lot.
I recently installed the SC restrictor (inverted cone) at the base of the breather hose and have not seen oil in the airbox since.
And you're right, vacuum is on top, that's the same vacuum line that goes to the distributor.

The membrane between the 2 lower sections seemed to be OK, it holds the vacuum.

John : yes vapors could make sense, especially with the oil in the intake.
The WUR is the lowest point of all the hoses, so condensed vapors running down from the airbox would end up in there.

ossiblue : I did not want to do any further disassembly as I could not find part numbers for the seals and other pieces that may need to be replaced.
So far the only seal that has been removed is the one for the vacuum section, and it could be reused, so it's OK.
Do you know where to source the seals and other rebuild parts ? PET shows the WUR as a single item.

I couldn't see any traces of gas around the disc, it was filled of sludge then I cleaned everything.
I'll probably assume the disc is good, put it back together, drive the car and look again.

-Guillaume

Ray_G · Ray_G's Garage

Guillaume,
Is there any possibility you have the PN for the restrictor you installed? If I run my oil level towards the maximum mark I get oil in my breather too. I need to get one. I don't have any trouble if the level is in the middle or lower.
Thanks,
Ray

tabasco · 12-08-2009, 11:29 AM

Ray,

the PN is 930 107 289 00.

It makes sense to have some restriction in the hose, tank side.
Otherwise, any oil that makes it to the top of the hose will come down on the airbox side, and ends up in the airbox.
The cone will limit the amount of oil that can go up the hose, and its velocity.
Then if some oil still makes it past the restrictor, it's very likely to go back down in the tank.

-Guillaume

john walker's workshop · 12-08-2009, 01:04 PM

Quote:

Originally Posted by Ray_G

I don't have any trouble if the level is in the middle or lower.
Thanks,
Ray

yes, that's why we recommend running it in the middle of the high/low area.

Ray_G · Ray_G's Garage

Quote:

Originally Posted by john walker's workshop

yes, that's why we recommend running it in the middle of the high/low area.

I figured it out the hard way! Anyway I want to put the restrictor in anyway.
Thanks the PN on the restrictor.

T77911S · 12-09-2009, 04:18 AM

Quote:

Originally Posted by john walker's workshop

yes, that's why we recommend running it in the middle of the high/low area.

i am glad you said it too. i never fill mine up. i found the higher it is, the faster it uses it. i have been waiting for someone to jump on me for recommending this.
i have verified the accuracy of my oil gage, when it shows low at idle, i dump another qrt in.