TheSamba.com :: View topic

Mon Jul 27, 2009 6:34 pm

I have a 1972 bay with a 1700, and in my reading of the Bently it states the arrow should point twoards the servo. Yet in postings here I have seen where the arrow should be twords the motor. In fact, inside the arrow on the valve is the word motor. So my question is which way should the valve point?

Mon Jul 27, 2009 6:48 pm

Toward the motor please.

It is a check valve and should only allow air (in the form of vacuum) to pass one way. YOu should not be able to blow through it the wrong way.

Tue Feb 23, 2010 12:28 pm

While I was under the bus adjusting my spring plates I had a look at my servo vacuum line. I'm in the process of redoing the brake system (new front rotors, rebuilt calipers, new front and rear flexible lines, and new German master cylinder). The servo line check valve is good, but I discovered a strange barbed hose connection forward of the valve. Sorry, no pics - but it looked like this:

Engine - plastic vacuum line - check valve - 2" rubber hose - 'split' barbed hose connector - plastic vacuum line up to servo.

The barbed hose connector is plastic and is sort of a 'Y' connector - one of the arms being about 1/10 the diameter of the other two barbed ends which are the same diameter. This smaller arm wasn't connected to anything. I'm assuming this is a PO hack that is creating a vacuum leak but want to make sure that it isn't supposed to be there.

One other thing regarding the servo itself. Before redoing the brakes, I would lose vacuum/servo function immediately after turning the engine off. I removed the servo along with the MC and can see a little brake fluid inside, but not enough to even get it to run out of the MC mount opening when held inverted. Thinking of just sending out to be rebuilt, but don't want to if unnecessary. Is even a slight amount of brake fluid in the servo enough to require a rebuild? Can it be cleaned out and bench tested? Wondering if that barbed connector was the only cause of the loss of vacuum with power off or if the servo diaphragm is bad too...

Any advice/insight is appreciated!

Tue Feb 23, 2010 1:24 pm

The small hose Tee'd into the booster line was for the early decel valve IIRC (can't remember exact use right now, maybe Scott will), if it's open it's definitely a big vacuum leak and likely the issue with the booster not holding vacuum.
Any fluid in the booster is not good, you can try washing it out with brake cleaner but sooner or later you should have it rebuilt. A sudden failure may or may not be life threatening, all depends on how strong your leg is and how fast you react to a sudden decrease in braking when you aren't expecting it :wink:

Tue Feb 23, 2010 2:39 pm

i know what it is for but i forget. honestly. iirc it's '75 only. maybe '74 CA also. the little hose connects to a vacuum switch but i forget what it's for. EGR maybe.

Tue Feb 23, 2010 2:42 pm

Good to hear it's not just me that's losing my mind :P
I've got a 74 auto (carbs) with that Tee in the shop right now but disconnected.

Tue Feb 23, 2010 3:18 pm

i just worked on a 74 that had it.

Thu Feb 25, 2010 11:07 am

OK, I've got a great memory, it's just really short :P :oops:

The tee upstream of the check valve is/was for the early EGR, VW put it there to utilize the stored vacuum in the booster system because manifold vacuum could be too low to open the EGR valve under full throttle conditions. Mostly found on automatics.

Thu Feb 25, 2010 8:23 pm

Found that tee in this microfiche (part #35): http://www.vagcat.com/p/B029/051100.png