What does this do? I need a new one...

[Joe87]

Anyone know what this bit of pipe does? Or what it's called? I need a new one but I have no idea what to ask for...As you can see I've broken off the little connecting pipe. Appears to have something to do with the brakes? Goes to the master cylinder and the broken bit goes to some kind of electronic switch. Any info would be much appreciated!

[andyneedham2]

I believe it's a non return valve (hence the arrows). Looks like it's for the vacuum,(dizzy, carb, master cylinder etc etc). You can get them from car building solutions online, someone will probably be along shortly to explain if there is a certain one to get. As long as you get the right hose diameter there shouldn't be a problem... hope that helps.

Andy

[MrD]

Mine also bust off flush with the pipe,as far as i can work out ( well on my gtx anyway ) It is something to do with the M.F.A possibly fuel related,as in fuel usage,just have mine taped up with leccy tape,as don`t have fuel gauge,just a sight tube on the fuel tank

[Chris16vRocco]

It's a vacuum check valve for the power brakes. It is something you'd need a specific replacement for, since there are multiple hoses going to it, which are different sizes. You should be able to find a used spare fairly easily in a junkyard.

[Joe87]

I figured out that it powers the fuel gauge and also either advances or retards the ignition (goes to a vacuum switch on the distributor). I've just used a T-piece to connect both of the small pipes to the same hole and blocked up the broken one, and everything seems to work fine.
Cheers.

[Funky Diver]

It's a non-return valve, as already said.

What it DOES is when you stick your foot down on the pedal, air fuel mix is allowed into the inlet manifold due to the Suck part of the engines cycle. This Suck creates a vacuum in the manifold. The intensity of the vacuum will determine how much sucking is actually going on, hence the reason it's connected to your MFA. The amount of suck will give a rough indication, when tied with speed, as to how much fuel you're using. The amount of suck will also advance the ignition by pulling the vac unit on the dizzy to advance the ignition. More suck = more advance. The amount of suck also gives the servo assist it's power in the brake servo. The suck is also used, when connected to the 2E2 carb, for fuel adjustment and warm idle control (the flap on the air box inlet) although this is done to a lesser extent. The green bulbous thing evens out the ripples in the vacuum to give a constant vacuum.

And yes, they're easy enough to come by off a scrapper, and not available new (unless someone at VW has found a box in a warehouse somewhere... part was listed obsolete last time I needed one)

Sorry if that's clouded the issue and not given a real answer.

Eligible part numbers for the valve are;

171 611 933
030 133 335 A
056 129 777 A

Cars without MFA use a rubber bung to bung up the non-required port. It just slips on... part number 056 129 777

[Boumsong]

You'll find a tonne of these in breakers all over the country, loads of older cars used this type of thing, most dubs up until the mid 90's had them as well.

[Nate]

I figured out that it powers the fuel gauge

#

erm, nope. fuel guage signal comes from a sender in the fuel tank ;)

but you've repaired it the way most people do.

[Joe87]

erm, nope. fuel guage signal comes from a sender in the fuel tank ;)

Oh ok...remind me not to trust the Haynes Manual next time I'm fixing a car :p

Thanks to everyone for the info anyway, will look into getting a new one now I know what it is.

[Chris16vRocco]

erm, nope. fuel guage signal comes from a sender in the fuel tank ;)

Oh ok...remind me not to trust the Haynes Manual next time I'm fixing a car :p

Haynes manual bad, Bentley manual good.

[hyperdrinky]

Haynes manual bad, Bentley manual good.

Bentley manual is only good if you have a US car. Every time I've tried to use it the information has been incorrect.

[Joe87]

What it DOES is when you stick your foot down on the pedal, air fuel mix is allowed into the inlet manifold due to the Suck part of the engines cycle. This Suck creates a vacuum in the manifold. The intensity of the vacuum will determine how much sucking is actually going on, hence the reason it's connected to your MFA. The amount of suck will give a rough indication, when tied with speed, as to how much fuel you're using. The amount of suck will also advance the ignition by pulling the vac unit on the dizzy to advance the ignition. More suck = more advance. The amount of suck also gives the servo assist it's power in the brake servo. The suck is also used, when connected to the 2E2 carb, for fuel adjustment and warm idle control (the flap on the air box inlet) although this is done to a lesser extent. The green bulbous thing evens out the ripples in the vacuum to give a constant vacuum.

This thing really sucks.


Sorry.

[Blueshark]

Have you already found one?.

Grtz, Joost

[Joe87]

Think so mate.